From 43245117806ff8914e37327b610fc08b5ddedc91 Mon Sep 17 00:00:00 2001 From: Yury Norov Date: Fri, 20 Jan 2023 20:24:28 -0800 Subject: [PATCH 1/9] lib/find: introduce find_nth_and_andnot_bit In the following patches the function is used to implement in-place bitmaps traversing without storing intermediate result in temporary bitmaps. Signed-off-by: Yury Norov Acked-by: Tariq Toukan Reviewed-by: Jacob Keller Reviewed-by: Peter Lafreniere Signed-off-by: Jakub Kicinski --- include/linux/find.h | 33 +++++++++++++++++++++++++++++++++ lib/find_bit.c | 9 +++++++++ 2 files changed, 42 insertions(+) diff --git a/include/linux/find.h b/include/linux/find.h index ccaf61a0f5fd5..4647864a5ffdb 100644 --- a/include/linux/find.h +++ b/include/linux/find.h @@ -22,6 +22,9 @@ unsigned long __find_nth_and_bit(const unsigned long *addr1, const unsigned long unsigned long size, unsigned long n); unsigned long __find_nth_andnot_bit(const unsigned long *addr1, const unsigned long *addr2, unsigned long size, unsigned long n); +unsigned long __find_nth_and_andnot_bit(const unsigned long *addr1, const unsigned long *addr2, + const unsigned long *addr3, unsigned long size, + unsigned long n); extern unsigned long _find_first_and_bit(const unsigned long *addr1, const unsigned long *addr2, unsigned long size); extern unsigned long _find_first_zero_bit(const unsigned long *addr, unsigned long size); @@ -255,6 +258,36 @@ unsigned long find_nth_andnot_bit(const unsigned long *addr1, const unsigned lon return __find_nth_andnot_bit(addr1, addr2, size, n); } +/** + * find_nth_and_andnot_bit - find N'th set bit in 2 memory regions, + * excluding those set in 3rd region + * @addr1: The 1st address to start the search at + * @addr2: The 2nd address to start the search at + * @addr3: The 3rd address to start the search at + * @size: The maximum number of bits to search + * @n: The number of set bit, which position is needed, counting from 0 + * + * Returns the bit number of the N'th set bit. + * If no such, returns @size. + */ +static __always_inline +unsigned long find_nth_and_andnot_bit(const unsigned long *addr1, + const unsigned long *addr2, + const unsigned long *addr3, + unsigned long size, unsigned long n) +{ + if (n >= size) + return size; + + if (small_const_nbits(size)) { + unsigned long val = *addr1 & *addr2 & (~*addr3) & GENMASK(size - 1, 0); + + return val ? fns(val, n) : size; + } + + return __find_nth_and_andnot_bit(addr1, addr2, addr3, size, n); +} + #ifndef find_first_and_bit /** * find_first_and_bit - find the first set bit in both memory regions diff --git a/lib/find_bit.c b/lib/find_bit.c index 18bc0a7ac8eed..c10920e667889 100644 --- a/lib/find_bit.c +++ b/lib/find_bit.c @@ -155,6 +155,15 @@ unsigned long __find_nth_andnot_bit(const unsigned long *addr1, const unsigned l } EXPORT_SYMBOL(__find_nth_andnot_bit); +unsigned long __find_nth_and_andnot_bit(const unsigned long *addr1, + const unsigned long *addr2, + const unsigned long *addr3, + unsigned long size, unsigned long n) +{ + return FIND_NTH_BIT(addr1[idx] & addr2[idx] & ~addr3[idx], size, n); +} +EXPORT_SYMBOL(__find_nth_and_andnot_bit); + #ifndef find_next_and_bit unsigned long _find_next_and_bit(const unsigned long *addr1, const unsigned long *addr2, unsigned long nbits, unsigned long start) From 62f4386e564d31c7d0ed7d835843e2685f99ae71 Mon Sep 17 00:00:00 2001 From: Yury Norov Date: Fri, 20 Jan 2023 20:24:29 -0800 Subject: [PATCH 2/9] cpumask: introduce cpumask_nth_and_andnot Introduce cpumask_nth_and_andnot() based on find_nth_and_andnot_bit(). It's used in the following patch to traverse cpumasks without storing intermediate result in temporary cpumask. Signed-off-by: Yury Norov Acked-by: Tariq Toukan Reviewed-by: Jacob Keller Reviewed-by: Peter Lafreniere Signed-off-by: Jakub Kicinski --- include/linux/cpumask.h | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h index c2aa0aa26b457..7b16aede7ac58 100644 --- a/include/linux/cpumask.h +++ b/include/linux/cpumask.h @@ -391,6 +391,26 @@ unsigned int cpumask_nth_andnot(unsigned int cpu, const struct cpumask *srcp1, nr_cpumask_bits, cpumask_check(cpu)); } +/** + * cpumask_nth_and_andnot - get the Nth cpu set in 1st and 2nd cpumask, and clear in 3rd. + * @srcp1: the cpumask pointer + * @srcp2: the cpumask pointer + * @srcp3: the cpumask pointer + * @cpu: the N'th cpu to find, starting from 0 + * + * Returns >= nr_cpu_ids if such cpu doesn't exist. + */ +static __always_inline +unsigned int cpumask_nth_and_andnot(unsigned int cpu, const struct cpumask *srcp1, + const struct cpumask *srcp2, + const struct cpumask *srcp3) +{ + return find_nth_and_andnot_bit(cpumask_bits(srcp1), + cpumask_bits(srcp2), + cpumask_bits(srcp3), + nr_cpumask_bits, cpumask_check(cpu)); +} + #define CPU_BITS_NONE \ { \ [0 ... BITS_TO_LONGS(NR_CPUS)-1] = 0UL \ From cd7f55359c90a4108e6528e326b8623fce1ad72a Mon Sep 17 00:00:00 2001 From: Yury Norov Date: Fri, 20 Jan 2023 20:24:30 -0800 Subject: [PATCH 3/9] sched: add sched_numa_find_nth_cpu() The function finds Nth set CPU in a given cpumask starting from a given node. Leveraging the fact that each hop in sched_domains_numa_masks includes the same or greater number of CPUs than the previous one, we can use binary search on hops instead of linear walk, which makes the overall complexity of O(log n) in terms of number of cpumask_weight() calls. Signed-off-by: Yury Norov Acked-by: Tariq Toukan Reviewed-by: Jacob Keller Reviewed-by: Peter Lafreniere Signed-off-by: Jakub Kicinski --- include/linux/topology.h | 8 ++++++ kernel/sched/topology.c | 57 ++++++++++++++++++++++++++++++++++++++++ 2 files changed, 65 insertions(+) diff --git a/include/linux/topology.h b/include/linux/topology.h index 4564faafd0e12..72f2645756982 100644 --- a/include/linux/topology.h +++ b/include/linux/topology.h @@ -245,5 +245,13 @@ static inline const struct cpumask *cpu_cpu_mask(int cpu) return cpumask_of_node(cpu_to_node(cpu)); } +#ifdef CONFIG_NUMA +int sched_numa_find_nth_cpu(const struct cpumask *cpus, int cpu, int node); +#else +static __always_inline int sched_numa_find_nth_cpu(const struct cpumask *cpus, int cpu, int node) +{ + return cpumask_nth(cpu, cpus); +} +#endif /* CONFIG_NUMA */ #endif /* _LINUX_TOPOLOGY_H */ diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index 8739c2a5a54ea..2bf89186a10fa 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -3,6 +3,8 @@ * Scheduler topology setup/handling methods */ +#include + DEFINE_MUTEX(sched_domains_mutex); /* Protected by sched_domains_mutex: */ @@ -2067,6 +2069,61 @@ int sched_numa_find_closest(const struct cpumask *cpus, int cpu) return found; } +struct __cmp_key { + const struct cpumask *cpus; + struct cpumask ***masks; + int node; + int cpu; + int w; +}; + +static int hop_cmp(const void *a, const void *b) +{ + struct cpumask **prev_hop = *((struct cpumask ***)b - 1); + struct cpumask **cur_hop = *(struct cpumask ***)b; + struct __cmp_key *k = (struct __cmp_key *)a; + + if (cpumask_weight_and(k->cpus, cur_hop[k->node]) <= k->cpu) + return 1; + + k->w = (b == k->masks) ? 0 : cpumask_weight_and(k->cpus, prev_hop[k->node]); + if (k->w <= k->cpu) + return 0; + + return -1; +} + +/* + * sched_numa_find_nth_cpu() - given the NUMA topology, find the Nth next cpu + * closest to @cpu from @cpumask. + * cpumask: cpumask to find a cpu from + * cpu: Nth cpu to find + * + * returns: cpu, or nr_cpu_ids when nothing found. + */ +int sched_numa_find_nth_cpu(const struct cpumask *cpus, int cpu, int node) +{ + struct __cmp_key k = { .cpus = cpus, .node = node, .cpu = cpu }; + struct cpumask ***hop_masks; + int hop, ret = nr_cpu_ids; + + rcu_read_lock(); + + k.masks = rcu_dereference(sched_domains_numa_masks); + if (!k.masks) + goto unlock; + + hop_masks = bsearch(&k, k.masks, sched_domains_numa_levels, sizeof(k.masks[0]), hop_cmp); + hop = hop_masks - k.masks; + + ret = hop ? + cpumask_nth_and_andnot(cpu - k.w, cpus, k.masks[hop][node], k.masks[hop-1][node]) : + cpumask_nth_and(cpu, cpus, k.masks[0][node]); +unlock: + rcu_read_unlock(); + return ret; +} +EXPORT_SYMBOL_GPL(sched_numa_find_nth_cpu); #endif /* CONFIG_NUMA */ static int __sdt_alloc(const struct cpumask *cpu_map) From 406d394abfcd8f16dc1dbcc8fc1b828252befb6d Mon Sep 17 00:00:00 2001 From: Yury Norov Date: Fri, 20 Jan 2023 20:24:31 -0800 Subject: [PATCH 4/9] cpumask: improve on cpumask_local_spread() locality Switch cpumask_local_spread() to use newly added sched_numa_find_nth_cpu(), which takes into account distances to each node in the system. For the following NUMA configuration: root@debian:~# numactl -H available: 4 nodes (0-3) node 0 cpus: 0 1 2 3 node 0 size: 3869 MB node 0 free: 3740 MB node 1 cpus: 4 5 node 1 size: 1969 MB node 1 free: 1937 MB node 2 cpus: 6 7 node 2 size: 1967 MB node 2 free: 1873 MB node 3 cpus: 8 9 10 11 12 13 14 15 node 3 size: 7842 MB node 3 free: 7723 MB node distances: node 0 1 2 3 0: 10 50 30 70 1: 50 10 70 30 2: 30 70 10 50 3: 70 30 50 10 The new cpumask_local_spread() traverses cpus for each node like this: node 0: 0 1 2 3 6 7 4 5 8 9 10 11 12 13 14 15 node 1: 4 5 8 9 10 11 12 13 14 15 0 1 2 3 6 7 node 2: 6 7 0 1 2 3 8 9 10 11 12 13 14 15 4 5 node 3: 8 9 10 11 12 13 14 15 4 5 6 7 0 1 2 3 Signed-off-by: Yury Norov Acked-by: Tariq Toukan Reviewed-by: Jacob Keller Reviewed-by: Peter Lafreniere Signed-off-by: Jakub Kicinski --- lib/cpumask.c | 12 ++---------- 1 file changed, 2 insertions(+), 10 deletions(-) diff --git a/lib/cpumask.c b/lib/cpumask.c index c7c392514fd34..255974cd6734f 100644 --- a/lib/cpumask.c +++ b/lib/cpumask.c @@ -110,7 +110,7 @@ void __init free_bootmem_cpumask_var(cpumask_var_t mask) #endif /** - * cpumask_local_spread - select the i'th cpu with local numa cpu's first + * cpumask_local_spread - select the i'th cpu based on NUMA distances * @i: index number * @node: local numa_node * @@ -132,15 +132,7 @@ unsigned int cpumask_local_spread(unsigned int i, int node) if (cpu < nr_cpu_ids) return cpu; } else { - /* NUMA first. */ - cpu = cpumask_nth_and(i, cpu_online_mask, cpumask_of_node(node)); - if (cpu < nr_cpu_ids) - return cpu; - - i -= cpumask_weight_and(cpu_online_mask, cpumask_of_node(node)); - - /* Skip NUMA nodes, done above. */ - cpu = cpumask_nth_andnot(i, cpu_online_mask, cpumask_of_node(node)); + cpu = sched_numa_find_nth_cpu(cpu_online_mask, i, node); if (cpu < nr_cpu_ids) return cpu; } From b1beed72b8b75d365fdbc925da856c212195051b Mon Sep 17 00:00:00 2001 From: Yury Norov Date: Fri, 20 Jan 2023 20:24:32 -0800 Subject: [PATCH 5/9] lib/cpumask: reorganize cpumask_local_spread() logic Now after moving all NUMA logic into sched_numa_find_nth_cpu(), else-branch of cpumask_local_spread() is just a function call, and we can simplify logic by using ternary operator. While here, replace BUG() with WARN_ON(). Signed-off-by: Yury Norov Acked-by: Tariq Toukan Reviewed-by: Jacob Keller Reviewed-by: Peter Lafreniere Signed-off-by: Jakub Kicinski --- lib/cpumask.c | 16 ++++++---------- 1 file changed, 6 insertions(+), 10 deletions(-) diff --git a/lib/cpumask.c b/lib/cpumask.c index 255974cd6734f..10aa15715c0d2 100644 --- a/lib/cpumask.c +++ b/lib/cpumask.c @@ -127,16 +127,12 @@ unsigned int cpumask_local_spread(unsigned int i, int node) /* Wrap: we always want a cpu. */ i %= num_online_cpus(); - if (node == NUMA_NO_NODE) { - cpu = cpumask_nth(i, cpu_online_mask); - if (cpu < nr_cpu_ids) - return cpu; - } else { - cpu = sched_numa_find_nth_cpu(cpu_online_mask, i, node); - if (cpu < nr_cpu_ids) - return cpu; - } - BUG(); + cpu = (node == NUMA_NO_NODE) ? + cpumask_nth(i, cpu_online_mask) : + sched_numa_find_nth_cpu(cpu_online_mask, i, node); + + WARN_ON(cpu >= nr_cpu_ids); + return cpu; } EXPORT_SYMBOL(cpumask_local_spread); From 9feae65845f7b16376716fe70b7d4b9bf8721848 Mon Sep 17 00:00:00 2001 From: Valentin Schneider Date: Fri, 20 Jan 2023 20:24:33 -0800 Subject: [PATCH 6/9] sched/topology: Introduce sched_numa_hop_mask() Tariq has pointed out that drivers allocating IRQ vectors would benefit from having smarter NUMA-awareness - cpumask_local_spread() only knows about the local node and everything outside is in the same bucket. sched_domains_numa_masks is pretty much what we want to hand out (a cpumask of CPUs reachable within a given distance budget), introduce sched_numa_hop_mask() to export those cpumasks. Link: http://lore.kernel.org/r/20220728191203.4055-1-tariqt@nvidia.com Signed-off-by: Valentin Schneider Reviewed-by: Yury Norov Signed-off-by: Yury Norov Signed-off-by: Jakub Kicinski --- include/linux/topology.h | 7 +++++++ kernel/sched/topology.c | 33 +++++++++++++++++++++++++++++++++ 2 files changed, 40 insertions(+) diff --git a/include/linux/topology.h b/include/linux/topology.h index 72f2645756982..344c2362755aa 100644 --- a/include/linux/topology.h +++ b/include/linux/topology.h @@ -247,11 +247,18 @@ static inline const struct cpumask *cpu_cpu_mask(int cpu) #ifdef CONFIG_NUMA int sched_numa_find_nth_cpu(const struct cpumask *cpus, int cpu, int node); +extern const struct cpumask *sched_numa_hop_mask(unsigned int node, unsigned int hops); #else static __always_inline int sched_numa_find_nth_cpu(const struct cpumask *cpus, int cpu, int node) { return cpumask_nth(cpu, cpus); } + +static inline const struct cpumask * +sched_numa_hop_mask(unsigned int node, unsigned int hops) +{ + return ERR_PTR(-EOPNOTSUPP); +} #endif /* CONFIG_NUMA */ #endif /* _LINUX_TOPOLOGY_H */ diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index 2bf89186a10fa..1233affc106c6 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -2124,6 +2124,39 @@ int sched_numa_find_nth_cpu(const struct cpumask *cpus, int cpu, int node) return ret; } EXPORT_SYMBOL_GPL(sched_numa_find_nth_cpu); + +/** + * sched_numa_hop_mask() - Get the cpumask of CPUs at most @hops hops away from + * @node + * @node: The node to count hops from. + * @hops: Include CPUs up to that many hops away. 0 means local node. + * + * Return: On success, a pointer to a cpumask of CPUs at most @hops away from + * @node, an error value otherwise. + * + * Requires rcu_lock to be held. Returned cpumask is only valid within that + * read-side section, copy it if required beyond that. + * + * Note that not all hops are equal in distance; see sched_init_numa() for how + * distances and masks are handled. + * Also note that this is a reflection of sched_domains_numa_masks, which may change + * during the lifetime of the system (offline nodes are taken out of the masks). + */ +const struct cpumask *sched_numa_hop_mask(unsigned int node, unsigned int hops) +{ + struct cpumask ***masks; + + if (node >= nr_node_ids || hops >= sched_domains_numa_levels) + return ERR_PTR(-EINVAL); + + masks = rcu_dereference(sched_domains_numa_masks); + if (!masks) + return ERR_PTR(-EBUSY); + + return masks[hops][node]; +} +EXPORT_SYMBOL_GPL(sched_numa_hop_mask); + #endif /* CONFIG_NUMA */ static int __sdt_alloc(const struct cpumask *cpu_map) From 06ac01721f7d07da722abe0ec6f147b90bfc8c77 Mon Sep 17 00:00:00 2001 From: Valentin Schneider Date: Fri, 20 Jan 2023 20:24:34 -0800 Subject: [PATCH 7/9] sched/topology: Introduce for_each_numa_hop_mask() The recently introduced sched_numa_hop_mask() exposes cpumasks of CPUs reachable within a given distance budget, wrap the logic for iterating over all (distance, mask) values inside an iterator macro. Signed-off-by: Valentin Schneider Reviewed-by: Yury Norov Signed-off-by: Yury Norov Signed-off-by: Jakub Kicinski --- include/linux/topology.h | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/include/linux/topology.h b/include/linux/topology.h index 344c2362755aa..fea32377f7c77 100644 --- a/include/linux/topology.h +++ b/include/linux/topology.h @@ -261,4 +261,22 @@ sched_numa_hop_mask(unsigned int node, unsigned int hops) } #endif /* CONFIG_NUMA */ +/** + * for_each_numa_hop_mask - iterate over cpumasks of increasing NUMA distance + * from a given node. + * @mask: the iteration variable. + * @node: the NUMA node to start the search from. + * + * Requires rcu_lock to be held. + * + * Yields cpu_online_mask for @node == NUMA_NO_NODE. + */ +#define for_each_numa_hop_mask(mask, node) \ + for (unsigned int __hops = 0; \ + mask = (node != NUMA_NO_NODE || __hops) ? \ + sched_numa_hop_mask(node, __hops) : \ + cpu_online_mask, \ + !IS_ERR_OR_NULL(mask); \ + __hops++) + #endif /* _LINUX_TOPOLOGY_H */ From 2acda57736de1e486036b90a648e67a3599080a1 Mon Sep 17 00:00:00 2001 From: Tariq Toukan Date: Fri, 20 Jan 2023 20:24:35 -0800 Subject: [PATCH 8/9] net/mlx5e: Improve remote NUMA preferences used for the IRQ affinity hints In the IRQ affinity hints, replace the binary NUMA preference (local / remote) with the improved for_each_numa_hop_cpu() API that minds the actual distances, so that remote NUMAs with short distance are preferred over farther ones. This has significant performance implications when using NUMA-aware allocated memory (follow [1] and derivatives for example). [1] drivers/net/ethernet/mellanox/mlx5/core/en_main.c :: mlx5e_open_channel() int cpu = cpumask_first(mlx5_comp_irq_get_affinity_mask(priv->mdev, ix)); Performance tests: TCP multi-stream, using 16 iperf3 instances pinned to 16 cores (with aRFS on). Active cores: 64,65,72,73,80,81,88,89,96,97,104,105,112,113,120,121 +-------------------------+-----------+------------------+------------------+ | | BW (Gbps) | TX side CPU util | RX side CPU util | +-------------------------+-----------+------------------+------------------+ | Baseline | 52.3 | 6.4 % | 17.9 % | +-------------------------+-----------+------------------+------------------+ | Applied on TX side only | 52.6 | 5.2 % | 18.5 % | +-------------------------+-----------+------------------+------------------+ | Applied on RX side only | 94.9 | 11.9 % | 27.2 % | +-------------------------+-----------+------------------+------------------+ | Applied on both sides | 95.1 | 8.4 % | 27.3 % | +-------------------------+-----------+------------------+------------------+ Bottleneck in RX side is released, reached linerate (~1.8x speedup). ~30% less cpu util on TX. * CPU util on active cores only. Setups details (similar for both sides): NIC: ConnectX6-DX dual port, 100 Gbps each. Single port used in the tests. $ lscpu Architecture: x86_64 CPU op-mode(s): 32-bit, 64-bit Byte Order: Little Endian CPU(s): 256 On-line CPU(s) list: 0-255 Thread(s) per core: 2 Core(s) per socket: 64 Socket(s): 2 NUMA node(s): 16 Vendor ID: AuthenticAMD CPU family: 25 Model: 1 Model name: AMD EPYC 7763 64-Core Processor Stepping: 1 CPU MHz: 2594.804 BogoMIPS: 4890.73 Virtualization: AMD-V L1d cache: 32K L1i cache: 32K L2 cache: 512K L3 cache: 32768K NUMA node0 CPU(s): 0-7,128-135 NUMA node1 CPU(s): 8-15,136-143 NUMA node2 CPU(s): 16-23,144-151 NUMA node3 CPU(s): 24-31,152-159 NUMA node4 CPU(s): 32-39,160-167 NUMA node5 CPU(s): 40-47,168-175 NUMA node6 CPU(s): 48-55,176-183 NUMA node7 CPU(s): 56-63,184-191 NUMA node8 CPU(s): 64-71,192-199 NUMA node9 CPU(s): 72-79,200-207 NUMA node10 CPU(s): 80-87,208-215 NUMA node11 CPU(s): 88-95,216-223 NUMA node12 CPU(s): 96-103,224-231 NUMA node13 CPU(s): 104-111,232-239 NUMA node14 CPU(s): 112-119,240-247 NUMA node15 CPU(s): 120-127,248-255 .. $ numactl -H .. node distances: node 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 0: 10 11 11 11 12 12 12 12 32 32 32 32 32 32 32 32 1: 11 10 11 11 12 12 12 12 32 32 32 32 32 32 32 32 2: 11 11 10 11 12 12 12 12 32 32 32 32 32 32 32 32 3: 11 11 11 10 12 12 12 12 32 32 32 32 32 32 32 32 4: 12 12 12 12 10 11 11 11 32 32 32 32 32 32 32 32 5: 12 12 12 12 11 10 11 11 32 32 32 32 32 32 32 32 6: 12 12 12 12 11 11 10 11 32 32 32 32 32 32 32 32 7: 12 12 12 12 11 11 11 10 32 32 32 32 32 32 32 32 8: 32 32 32 32 32 32 32 32 10 11 11 11 12 12 12 12 9: 32 32 32 32 32 32 32 32 11 10 11 11 12 12 12 12 10: 32 32 32 32 32 32 32 32 11 11 10 11 12 12 12 12 11: 32 32 32 32 32 32 32 32 11 11 11 10 12 12 12 12 12: 32 32 32 32 32 32 32 32 12 12 12 12 10 11 11 11 13: 32 32 32 32 32 32 32 32 12 12 12 12 11 10 11 11 14: 32 32 32 32 32 32 32 32 12 12 12 12 11 11 10 11 15: 32 32 32 32 32 32 32 32 12 12 12 12 11 11 11 10 $ cat /sys/class/net/ens5f0/device/numa_node 14 Affinity hints (127 IRQs): Before: 331: 00000000,00000000,00000000,00000000,00010000,00000000,00000000,00000000 332: 00000000,00000000,00000000,00000000,00020000,00000000,00000000,00000000 333: 00000000,00000000,00000000,00000000,00040000,00000000,00000000,00000000 334: 00000000,00000000,00000000,00000000,00080000,00000000,00000000,00000000 335: 00000000,00000000,00000000,00000000,00100000,00000000,00000000,00000000 336: 00000000,00000000,00000000,00000000,00200000,00000000,00000000,00000000 337: 00000000,00000000,00000000,00000000,00400000,00000000,00000000,00000000 338: 00000000,00000000,00000000,00000000,00800000,00000000,00000000,00000000 339: 00010000,00000000,00000000,00000000,00000000,00000000,00000000,00000000 340: 00020000,00000000,00000000,00000000,00000000,00000000,00000000,00000000 341: 00040000,00000000,00000000,00000000,00000000,00000000,00000000,00000000 342: 00080000,00000000,00000000,00000000,00000000,00000000,00000000,00000000 343: 00100000,00000000,00000000,00000000,00000000,00000000,00000000,00000000 344: 00200000,00000000,00000000,00000000,00000000,00000000,00000000,00000000 345: 00400000,00000000,00000000,00000000,00000000,00000000,00000000,00000000 346: 00800000,00000000,00000000,00000000,00000000,00000000,00000000,00000000 347: 00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000001 348: 00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000002 349: 00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000004 350: 00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000008 351: 00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000010 352: 00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000020 353: 00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000040 354: 00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000080 355: 00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000100 356: 00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000200 357: 00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000400 358: 00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000800 359: 00000000,00000000,00000000,00000000,00000000,00000000,00000000,00001000 360: 00000000,00000000,00000000,00000000,00000000,00000000,00000000,00002000 361: 00000000,00000000,00000000,00000000,00000000,00000000,00000000,00004000 362: 00000000,00000000,00000000,00000000,00000000,00000000,00000000,00008000 363: 00000000,00000000,00000000,00000000,00000000,00000000,00000000,00010000 364: 00000000,00000000,00000000,00000000,00000000,00000000,00000000,00020000 365: 00000000,00000000,00000000,00000000,00000000,00000000,00000000,00040000 366: 00000000,00000000,00000000,00000000,00000000,00000000,00000000,00080000 367: 00000000,00000000,00000000,00000000,00000000,00000000,00000000,00100000 368: 00000000,00000000,00000000,00000000,00000000,00000000,00000000,00200000 369: 00000000,00000000,00000000,00000000,00000000,00000000,00000000,00400000 370: 00000000,00000000,00000000,00000000,00000000,00000000,00000000,00800000 371: 00000000,00000000,00000000,00000000,00000000,00000000,00000000,01000000 372: 00000000,00000000,00000000,00000000,00000000,00000000,00000000,02000000 373: 00000000,00000000,00000000,00000000,00000000,00000000,00000000,04000000 374: 00000000,00000000,00000000,00000000,00000000,00000000,00000000,08000000 375: 00000000,00000000,00000000,00000000,00000000,00000000,00000000,10000000 376: 00000000,00000000,00000000,00000000,00000000,00000000,00000000,20000000 377: 00000000,00000000,00000000,00000000,00000000,00000000,00000000,40000000 378: 00000000,00000000,00000000,00000000,00000000,00000000,00000000,80000000 379: 00000000,00000000,00000000,00000000,00000000,00000000,00000001,00000000 380: 00000000,00000000,00000000,00000000,00000000,00000000,00000002,00000000 381: 00000000,00000000,00000000,00000000,00000000,00000000,00000004,00000000 382: 00000000,00000000,00000000,00000000,00000000,00000000,00000008,00000000 383: 00000000,00000000,00000000,00000000,00000000,00000000,00000010,00000000 384: 00000000,00000000,00000000,00000000,00000000,00000000,00000020,00000000 385: 00000000,00000000,00000000,00000000,00000000,00000000,00000040,00000000 386: 00000000,00000000,00000000,00000000,00000000,00000000,00000080,00000000 387: 00000000,00000000,00000000,00000000,00000000,00000000,00000100,00000000 388: 00000000,00000000,00000000,00000000,00000000,00000000,00000200,00000000 389: 00000000,00000000,00000000,00000000,00000000,00000000,00000400,00000000 390: 00000000,00000000,00000000,00000000,00000000,00000000,00000800,00000000 391: 00000000,00000000,00000000,00000000,00000000,00000000,00001000,00000000 392: 00000000,00000000,00000000,00000000,00000000,00000000,00002000,00000000 393: 00000000,00000000,00000000,00000000,00000000,00000000,00004000,00000000 394: 00000000,00000000,00000000,00000000,00000000,00000000,00008000,00000000 395: 00000000,00000000,00000000,00000000,00000000,00000000,00010000,00000000 396: 00000000,00000000,00000000,00000000,00000000,00000000,00020000,00000000 397: 00000000,00000000,00000000,00000000,00000000,00000000,00040000,00000000 398: 00000000,00000000,00000000,00000000,00000000,00000000,00080000,00000000 399: 00000000,00000000,00000000,00000000,00000000,00000000,00100000,00000000 400: 00000000,00000000,00000000,00000000,00000000,00000000,00200000,00000000 401: 00000000,00000000,00000000,00000000,00000000,00000000,00400000,00000000 402: 00000000,00000000,00000000,00000000,00000000,00000000,00800000,00000000 403: 00000000,00000000,00000000,00000000,00000000,00000000,01000000,00000000 404: 00000000,00000000,00000000,00000000,00000000,00000000,02000000,00000000 405: 00000000,00000000,00000000,00000000,00000000,00000000,04000000,00000000 406: 00000000,00000000,00000000,00000000,00000000,00000000,08000000,00000000 407: 00000000,00000000,00000000,00000000,00000000,00000000,10000000,00000000 408: 00000000,00000000,00000000,00000000,00000000,00000000,20000000,00000000 409: 00000000,00000000,00000000,00000000,00000000,00000000,40000000,00000000 410: 00000000,00000000,00000000,00000000,00000000,00000000,80000000,00000000 411: 00000000,00000000,00000000,00000000,00000000,00000001,00000000,00000000 412: 00000000,00000000,00000000,00000000,00000000,00000002,00000000,00000000 413: 00000000,00000000,00000000,00000000,00000000,00000004,00000000,00000000 414: 00000000,00000000,00000000,00000000,00000000,00000008,00000000,00000000 415: 00000000,00000000,00000000,00000000,00000000,00000010,00000000,00000000 416: 00000000,00000000,00000000,00000000,00000000,00000020,00000000,00000000 417: 00000000,00000000,00000000,00000000,00000000,00000040,00000000,00000000 418: 00000000,00000000,00000000,00000000,00000000,00000080,00000000,00000000 419: 00000000,00000000,00000000,00000000,00000000,00000100,00000000,00000000 420: 00000000,00000000,00000000,00000000,00000000,00000200,00000000,00000000 421: 00000000,00000000,00000000,00000000,00000000,00000400,00000000,00000000 422: 00000000,00000000,00000000,00000000,00000000,00000800,00000000,00000000 423: 00000000,00000000,00000000,00000000,00000000,00001000,00000000,00000000 424: 00000000,00000000,00000000,00000000,00000000,00002000,00000000,00000000 425: 00000000,00000000,00000000,00000000,00000000,00004000,00000000,00000000 426: 00000000,00000000,00000000,00000000,00000000,00008000,00000000,00000000 427: 00000000,00000000,00000000,00000000,00000000,00010000,00000000,00000000 428: 00000000,00000000,00000000,00000000,00000000,00020000,00000000,00000000 429: 00000000,00000000,00000000,00000000,00000000,00040000,00000000,00000000 430: 00000000,00000000,00000000,00000000,00000000,00080000,00000000,00000000 431: 00000000,00000000,00000000,00000000,00000000,00100000,00000000,00000000 432: 00000000,00000000,00000000,00000000,00000000,00200000,00000000,00000000 433: 00000000,00000000,00000000,00000000,00000000,00400000,00000000,00000000 434: 00000000,00000000,00000000,00000000,00000000,00800000,00000000,00000000 435: 00000000,00000000,00000000,00000000,00000000,01000000,00000000,00000000 436: 00000000,00000000,00000000,00000000,00000000,02000000,00000000,00000000 437: 00000000,00000000,00000000,00000000,00000000,04000000,00000000,00000000 438: 00000000,00000000,00000000,00000000,00000000,08000000,00000000,00000000 439: 00000000,00000000,00000000,00000000,00000000,10000000,00000000,00000000 440: 00000000,00000000,00000000,00000000,00000000,20000000,00000000,00000000 441: 00000000,00000000,00000000,00000000,00000000,40000000,00000000,00000000 442: 00000000,00000000,00000000,00000000,00000000,80000000,00000000,00000000 443: 00000000,00000000,00000000,00000000,00000001,00000000,00000000,00000000 444: 00000000,00000000,00000000,00000000,00000002,00000000,00000000,00000000 445: 00000000,00000000,00000000,00000000,00000004,00000000,00000000,00000000 446: 00000000,00000000,00000000,00000000,00000008,00000000,00000000,00000000 447: 00000000,00000000,00000000,00000000,00000010,00000000,00000000,00000000 448: 00000000,00000000,00000000,00000000,00000020,00000000,00000000,00000000 449: 00000000,00000000,00000000,00000000,00000040,00000000,00000000,00000000 450: 00000000,00000000,00000000,00000000,00000080,00000000,00000000,00000000 451: 00000000,00000000,00000000,00000000,00000100,00000000,00000000,00000000 452: 00000000,00000000,00000000,00000000,00000200,00000000,00000000,00000000 453: 00000000,00000000,00000000,00000000,00000400,00000000,00000000,00000000 454: 00000000,00000000,00000000,00000000,00000800,00000000,00000000,00000000 455: 00000000,00000000,00000000,00000000,00001000,00000000,00000000,00000000 456: 00000000,00000000,00000000,00000000,00002000,00000000,00000000,00000000 457: 00000000,00000000,00000000,00000000,00004000,00000000,00000000,00000000 After: 331: 00000000,00000000,00000000,00000000,00010000,00000000,00000000,00000000 332: 00000000,00000000,00000000,00000000,00020000,00000000,00000000,00000000 333: 00000000,00000000,00000000,00000000,00040000,00000000,00000000,00000000 334: 00000000,00000000,00000000,00000000,00080000,00000000,00000000,00000000 335: 00000000,00000000,00000000,00000000,00100000,00000000,00000000,00000000 336: 00000000,00000000,00000000,00000000,00200000,00000000,00000000,00000000 337: 00000000,00000000,00000000,00000000,00400000,00000000,00000000,00000000 338: 00000000,00000000,00000000,00000000,00800000,00000000,00000000,00000000 339: 00010000,00000000,00000000,00000000,00000000,00000000,00000000,00000000 340: 00020000,00000000,00000000,00000000,00000000,00000000,00000000,00000000 341: 00040000,00000000,00000000,00000000,00000000,00000000,00000000,00000000 342: 00080000,00000000,00000000,00000000,00000000,00000000,00000000,00000000 343: 00100000,00000000,00000000,00000000,00000000,00000000,00000000,00000000 344: 00200000,00000000,00000000,00000000,00000000,00000000,00000000,00000000 345: 00400000,00000000,00000000,00000000,00000000,00000000,00000000,00000000 346: 00800000,00000000,00000000,00000000,00000000,00000000,00000000,00000000 347: 00000000,00000000,00000000,00000000,00000001,00000000,00000000,00000000 348: 00000000,00000000,00000000,00000000,00000002,00000000,00000000,00000000 349: 00000000,00000000,00000000,00000000,00000004,00000000,00000000,00000000 350: 00000000,00000000,00000000,00000000,00000008,00000000,00000000,00000000 351: 00000000,00000000,00000000,00000000,00000010,00000000,00000000,00000000 352: 00000000,00000000,00000000,00000000,00000020,00000000,00000000,00000000 353: 00000000,00000000,00000000,00000000,00000040,00000000,00000000,00000000 354: 00000000,00000000,00000000,00000000,00000080,00000000,00000000,00000000 355: 00000000,00000000,00000000,00000000,00000100,00000000,00000000,00000000 356: 00000000,00000000,00000000,00000000,00000200,00000000,00000000,00000000 357: 00000000,00000000,00000000,00000000,00000400,00000000,00000000,00000000 358: 00000000,00000000,00000000,00000000,00000800,00000000,00000000,00000000 359: 00000000,00000000,00000000,00000000,00001000,00000000,00000000,00000000 360: 00000000,00000000,00000000,00000000,00002000,00000000,00000000,00000000 361: 00000000,00000000,00000000,00000000,00004000,00000000,00000000,00000000 362: 00000000,00000000,00000000,00000000,00008000,00000000,00000000,00000000 363: 00000000,00000000,00000000,00000000,01000000,00000000,00000000,00000000 364: 00000000,00000000,00000000,00000000,02000000,00000000,00000000,00000000 365: 00000000,00000000,00000000,00000000,04000000,00000000,00000000,00000000 366: 00000000,00000000,00000000,00000000,08000000,00000000,00000000,00000000 367: 00000000,00000000,00000000,00000000,10000000,00000000,00000000,00000000 368: 00000000,00000000,00000000,00000000,20000000,00000000,00000000,00000000 369: 00000000,00000000,00000000,00000000,40000000,00000000,00000000,00000000 370: 00000000,00000000,00000000,00000000,80000000,00000000,00000000,00000000 371: 00000001,00000000,00000000,00000000,00000000,00000000,00000000,00000000 372: 00000002,00000000,00000000,00000000,00000000,00000000,00000000,00000000 373: 00000004,00000000,00000000,00000000,00000000,00000000,00000000,00000000 374: 00000008,00000000,00000000,00000000,00000000,00000000,00000000,00000000 375: 00000010,00000000,00000000,00000000,00000000,00000000,00000000,00000000 376: 00000020,00000000,00000000,00000000,00000000,00000000,00000000,00000000 377: 00000040,00000000,00000000,00000000,00000000,00000000,00000000,00000000 378: 00000080,00000000,00000000,00000000,00000000,00000000,00000000,00000000 379: 00000100,00000000,00000000,00000000,00000000,00000000,00000000,00000000 380: 00000200,00000000,00000000,00000000,00000000,00000000,00000000,00000000 381: 00000400,00000000,00000000,00000000,00000000,00000000,00000000,00000000 382: 00000800,00000000,00000000,00000000,00000000,00000000,00000000,00000000 383: 00001000,00000000,00000000,00000000,00000000,00000000,00000000,00000000 384: 00002000,00000000,00000000,00000000,00000000,00000000,00000000,00000000 385: 00004000,00000000,00000000,00000000,00000000,00000000,00000000,00000000 386: 00008000,00000000,00000000,00000000,00000000,00000000,00000000,00000000 387: 01000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000 388: 02000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000 389: 04000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000 390: 08000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000 391: 10000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000 392: 20000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000 393: 40000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000 394: 80000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000 395: 00000000,00000000,00000000,00000000,00000000,00000001,00000000,00000000 396: 00000000,00000000,00000000,00000000,00000000,00000002,00000000,00000000 397: 00000000,00000000,00000000,00000000,00000000,00000004,00000000,00000000 398: 00000000,00000000,00000000,00000000,00000000,00000008,00000000,00000000 399: 00000000,00000000,00000000,00000000,00000000,00000010,00000000,00000000 400: 00000000,00000000,00000000,00000000,00000000,00000020,00000000,00000000 401: 00000000,00000000,00000000,00000000,00000000,00000040,00000000,00000000 402: 00000000,00000000,00000000,00000000,00000000,00000080,00000000,00000000 403: 00000000,00000000,00000000,00000000,00000000,00000100,00000000,00000000 404: 00000000,00000000,00000000,00000000,00000000,00000200,00000000,00000000 405: 00000000,00000000,00000000,00000000,00000000,00000400,00000000,00000000 406: 00000000,00000000,00000000,00000000,00000000,00000800,00000000,00000000 407: 00000000,00000000,00000000,00000000,00000000,00001000,00000000,00000000 408: 00000000,00000000,00000000,00000000,00000000,00002000,00000000,00000000 409: 00000000,00000000,00000000,00000000,00000000,00004000,00000000,00000000 410: 00000000,00000000,00000000,00000000,00000000,00008000,00000000,00000000 411: 00000000,00000000,00000000,00000000,00000000,00010000,00000000,00000000 412: 00000000,00000000,00000000,00000000,00000000,00020000,00000000,00000000 413: 00000000,00000000,00000000,00000000,00000000,00040000,00000000,00000000 414: 00000000,00000000,00000000,00000000,00000000,00080000,00000000,00000000 415: 00000000,00000000,00000000,00000000,00000000,00100000,00000000,00000000 416: 00000000,00000000,00000000,00000000,00000000,00200000,00000000,00000000 417: 00000000,00000000,00000000,00000000,00000000,00400000,00000000,00000000 418: 00000000,00000000,00000000,00000000,00000000,00800000,00000000,00000000 419: 00000000,00000000,00000000,00000000,00000000,01000000,00000000,00000000 420: 00000000,00000000,00000000,00000000,00000000,02000000,00000000,00000000 421: 00000000,00000000,00000000,00000000,00000000,04000000,00000000,00000000 422: 00000000,00000000,00000000,00000000,00000000,08000000,00000000,00000000 423: 00000000,00000000,00000000,00000000,00000000,10000000,00000000,00000000 424: 00000000,00000000,00000000,00000000,00000000,20000000,00000000,00000000 425: 00000000,00000000,00000000,00000000,00000000,40000000,00000000,00000000 426: 00000000,00000000,00000000,00000000,00000000,80000000,00000000,00000000 427: 00000000,00000001,00000000,00000000,00000000,00000000,00000000,00000000 428: 00000000,00000002,00000000,00000000,00000000,00000000,00000000,00000000 429: 00000000,00000004,00000000,00000000,00000000,00000000,00000000,00000000 430: 00000000,00000008,00000000,00000000,00000000,00000000,00000000,00000000 431: 00000000,00000010,00000000,00000000,00000000,00000000,00000000,00000000 432: 00000000,00000020,00000000,00000000,00000000,00000000,00000000,00000000 433: 00000000,00000040,00000000,00000000,00000000,00000000,00000000,00000000 434: 00000000,00000080,00000000,00000000,00000000,00000000,00000000,00000000 435: 00000000,00000100,00000000,00000000,00000000,00000000,00000000,00000000 436: 00000000,00000200,00000000,00000000,00000000,00000000,00000000,00000000 437: 00000000,00000400,00000000,00000000,00000000,00000000,00000000,00000000 438: 00000000,00000800,00000000,00000000,00000000,00000000,00000000,00000000 439: 00000000,00001000,00000000,00000000,00000000,00000000,00000000,00000000 440: 00000000,00002000,00000000,00000000,00000000,00000000,00000000,00000000 441: 00000000,00004000,00000000,00000000,00000000,00000000,00000000,00000000 442: 00000000,00008000,00000000,00000000,00000000,00000000,00000000,00000000 443: 00000000,00010000,00000000,00000000,00000000,00000000,00000000,00000000 444: 00000000,00020000,00000000,00000000,00000000,00000000,00000000,00000000 445: 00000000,00040000,00000000,00000000,00000000,00000000,00000000,00000000 446: 00000000,00080000,00000000,00000000,00000000,00000000,00000000,00000000 447: 00000000,00100000,00000000,00000000,00000000,00000000,00000000,00000000 448: 00000000,00200000,00000000,00000000,00000000,00000000,00000000,00000000 449: 00000000,00400000,00000000,00000000,00000000,00000000,00000000,00000000 450: 00000000,00800000,00000000,00000000,00000000,00000000,00000000,00000000 451: 00000000,01000000,00000000,00000000,00000000,00000000,00000000,00000000 452: 00000000,02000000,00000000,00000000,00000000,00000000,00000000,00000000 453: 00000000,04000000,00000000,00000000,00000000,00000000,00000000,00000000 454: 00000000,08000000,00000000,00000000,00000000,00000000,00000000,00000000 455: 00000000,10000000,00000000,00000000,00000000,00000000,00000000,00000000 456: 00000000,20000000,00000000,00000000,00000000,00000000,00000000,00000000 457: 00000000,40000000,00000000,00000000,00000000,00000000,00000000,00000000 Signed-off-by: Tariq Toukan [Tweaked API use] Suggested-by: Yury Norov Signed-off-by: Valentin Schneider Reviewed-by: Yury Norov Signed-off-by: Yury Norov Signed-off-by: Jakub Kicinski --- drivers/net/ethernet/mellanox/mlx5/core/eq.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) diff --git a/drivers/net/ethernet/mellanox/mlx5/core/eq.c b/drivers/net/ethernet/mellanox/mlx5/core/eq.c index 9b44557e7271b..66ec7932f0084 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/eq.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/eq.c @@ -817,9 +817,12 @@ static void comp_irqs_release(struct mlx5_core_dev *dev) static int comp_irqs_request(struct mlx5_core_dev *dev) { struct mlx5_eq_table *table = dev->priv.eq_table; + const struct cpumask *prev = cpu_none_mask; + const struct cpumask *mask; int ncomp_eqs = table->num_comp_eqs; u16 *cpus; int ret; + int cpu; int i; ncomp_eqs = table->num_comp_eqs; @@ -838,8 +841,19 @@ static int comp_irqs_request(struct mlx5_core_dev *dev) ret = -ENOMEM; goto free_irqs; } - for (i = 0; i < ncomp_eqs; i++) - cpus[i] = cpumask_local_spread(i, dev->priv.numa_node); + + i = 0; + rcu_read_lock(); + for_each_numa_hop_mask(mask, dev->priv.numa_node) { + for_each_cpu_andnot(cpu, mask, prev) { + cpus[i] = cpu; + if (++i == ncomp_eqs) + goto spread_done; + } + prev = mask; + } +spread_done: + rcu_read_unlock(); ret = mlx5_irqs_request_vectors(dev, cpus, ncomp_eqs, table->comp_irqs); kfree(cpus); if (ret < 0) From 2ac4980c57f54db7c5b416f7946d2921fc16d9d2 Mon Sep 17 00:00:00 2001 From: Yury Norov Date: Fri, 20 Jan 2023 20:24:36 -0800 Subject: [PATCH 9/9] lib/cpumask: update comment for cpumask_local_spread() Now that we have an iterator-based alternative for a very common case of using cpumask_local_spread for all cpus in a row, it's worth to mention that in comment to cpumask_local_spread(). Signed-off-by: Yury Norov Reviewed-by: Valentin Schneider Reviewed-by: Tariq Toukan Signed-off-by: Jakub Kicinski --- lib/cpumask.c | 26 ++++++++++++++++++++++---- 1 file changed, 22 insertions(+), 4 deletions(-) diff --git a/lib/cpumask.c b/lib/cpumask.c index 10aa15715c0d2..e7258836b60b7 100644 --- a/lib/cpumask.c +++ b/lib/cpumask.c @@ -114,11 +114,29 @@ void __init free_bootmem_cpumask_var(cpumask_var_t mask) * @i: index number * @node: local numa_node * - * This function selects an online CPU according to a numa aware policy; - * local cpus are returned first, followed by non-local ones, then it - * wraps around. + * Returns online CPU according to a numa aware policy; local cpus are returned + * first, followed by non-local ones, then it wraps around. * - * It's not very efficient, but useful for setup. + * For those who wants to enumerate all CPUs based on their NUMA distances, + * i.e. call this function in a loop, like: + * + * for (i = 0; i < num_online_cpus(); i++) { + * cpu = cpumask_local_spread(i, node); + * do_something(cpu); + * } + * + * There's a better alternative based on for_each()-like iterators: + * + * for_each_numa_hop_mask(mask, node) { + * for_each_cpu_andnot(cpu, mask, prev) + * do_something(cpu); + * prev = mask; + * } + * + * It's simpler and more verbose than above. Complexity of iterator-based + * enumeration is O(sched_domains_numa_levels * nr_cpu_ids), while + * cpumask_local_spread() when called for each cpu is + * O(sched_domains_numa_levels * nr_cpu_ids * log(nr_cpu_ids)). */ unsigned int cpumask_local_spread(unsigned int i, int node) {