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net: openvswitch: make masks cache size configurable
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This patch makes the masks cache size configurable, or with
a size of 0, disable it.

Reviewed-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Tonghao Zhang <xiangxia.m.yue@gmail.com>
Signed-off-by: Eelco Chaudron <echaudro@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Eelco Chaudron authored and David S. Miller committed Aug 3, 2020
1 parent 9d2f627 commit 9bf24f5
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Showing 4 changed files with 115 additions and 14 deletions.
1 change: 1 addition & 0 deletions include/uapi/linux/openvswitch.h
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Original file line number Diff line number Diff line change
Expand Up @@ -86,6 +86,7 @@ enum ovs_datapath_attr {
OVS_DP_ATTR_MEGAFLOW_STATS, /* struct ovs_dp_megaflow_stats */
OVS_DP_ATTR_USER_FEATURES, /* OVS_DP_F_* */
OVS_DP_ATTR_PAD,
OVS_DP_ATTR_MASKS_CACHE_SIZE,
__OVS_DP_ATTR_MAX
};

Expand Down
17 changes: 17 additions & 0 deletions net/openvswitch/datapath.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1498,6 +1498,7 @@ static size_t ovs_dp_cmd_msg_size(void)
msgsize += nla_total_size_64bit(sizeof(struct ovs_dp_stats));
msgsize += nla_total_size_64bit(sizeof(struct ovs_dp_megaflow_stats));
msgsize += nla_total_size(sizeof(u32)); /* OVS_DP_ATTR_USER_FEATURES */
msgsize += nla_total_size(sizeof(u32)); /* OVS_DP_ATTR_MASKS_CACHE_SIZE */

return msgsize;
}
Expand Down Expand Up @@ -1535,6 +1536,10 @@ static int ovs_dp_cmd_fill_info(struct datapath *dp, struct sk_buff *skb,
if (nla_put_u32(skb, OVS_DP_ATTR_USER_FEATURES, dp->user_features))
goto nla_put_failure;

if (nla_put_u32(skb, OVS_DP_ATTR_MASKS_CACHE_SIZE,
ovs_flow_tbl_masks_cache_size(&dp->table)))
goto nla_put_failure;

genlmsg_end(skb, ovs_header);
return 0;

Expand Down Expand Up @@ -1599,6 +1604,16 @@ static int ovs_dp_change(struct datapath *dp, struct nlattr *a[])
#endif
}

if (a[OVS_DP_ATTR_MASKS_CACHE_SIZE]) {
int err;
u32 cache_size;

cache_size = nla_get_u32(a[OVS_DP_ATTR_MASKS_CACHE_SIZE]);
err = ovs_flow_tbl_masks_cache_resize(&dp->table, cache_size);
if (err)
return err;
}

dp->user_features = user_features;

if (dp->user_features & OVS_DP_F_TC_RECIRC_SHARING)
Expand Down Expand Up @@ -1887,6 +1902,8 @@ static const struct nla_policy datapath_policy[OVS_DP_ATTR_MAX + 1] = {
[OVS_DP_ATTR_NAME] = { .type = NLA_NUL_STRING, .len = IFNAMSIZ - 1 },
[OVS_DP_ATTR_UPCALL_PID] = { .type = NLA_U32 },
[OVS_DP_ATTR_USER_FEATURES] = { .type = NLA_U32 },
[OVS_DP_ATTR_MASKS_CACHE_SIZE] = NLA_POLICY_RANGE(NLA_U32, 0,
PCPU_MIN_UNIT_SIZE / sizeof(struct mask_cache_entry)),
};

static const struct genl_ops dp_datapath_genl_ops[] = {
Expand Down
101 changes: 88 additions & 13 deletions net/openvswitch/flow_table.c
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Original file line number Diff line number Diff line change
Expand Up @@ -38,8 +38,8 @@
#define MASK_ARRAY_SIZE_MIN 16
#define REHASH_INTERVAL (10 * 60 * HZ)

#define MC_DEFAULT_HASH_ENTRIES 256
#define MC_HASH_SHIFT 8
#define MC_HASH_ENTRIES (1u << MC_HASH_SHIFT)
#define MC_HASH_SEGS ((sizeof(uint32_t) * 8) / MC_HASH_SHIFT)

static struct kmem_cache *flow_cache;
Expand Down Expand Up @@ -341,15 +341,79 @@ static void flow_mask_remove(struct flow_table *tbl, struct sw_flow_mask *mask)
}
}

static void __mask_cache_destroy(struct mask_cache *mc)
{
free_percpu(mc->mask_cache);
kfree(mc);
}

static void mask_cache_rcu_cb(struct rcu_head *rcu)
{
struct mask_cache *mc = container_of(rcu, struct mask_cache, rcu);

__mask_cache_destroy(mc);
}

static struct mask_cache *tbl_mask_cache_alloc(u32 size)
{
struct mask_cache_entry __percpu *cache = NULL;
struct mask_cache *new;

/* Only allow size to be 0, or a power of 2, and does not exceed
* percpu allocation size.
*/
if ((!is_power_of_2(size) && size != 0) ||
(size * sizeof(struct mask_cache_entry)) > PCPU_MIN_UNIT_SIZE)
return NULL;

new = kzalloc(sizeof(*new), GFP_KERNEL);
if (!new)
return NULL;

new->cache_size = size;
if (new->cache_size > 0) {
cache = __alloc_percpu(array_size(sizeof(struct mask_cache_entry),
new->cache_size),
__alignof__(struct mask_cache_entry));
if (!cache) {
kfree(new);
return NULL;
}
}

new->mask_cache = cache;
return new;
}
int ovs_flow_tbl_masks_cache_resize(struct flow_table *table, u32 size)
{
struct mask_cache *mc = rcu_dereference(table->mask_cache);
struct mask_cache *new;

if (size == mc->cache_size)
return 0;

if ((!is_power_of_2(size) && size != 0) ||
(size * sizeof(struct mask_cache_entry)) > PCPU_MIN_UNIT_SIZE)
return -EINVAL;

new = tbl_mask_cache_alloc(size);
if (!new)
return -ENOMEM;

rcu_assign_pointer(table->mask_cache, new);
call_rcu(&mc->rcu, mask_cache_rcu_cb);

return 0;
}

int ovs_flow_tbl_init(struct flow_table *table)
{
struct table_instance *ti, *ufid_ti;
struct mask_cache *mc;
struct mask_array *ma;

table->mask_cache = __alloc_percpu(sizeof(struct mask_cache_entry) *
MC_HASH_ENTRIES,
__alignof__(struct mask_cache_entry));
if (!table->mask_cache)
mc = tbl_mask_cache_alloc(MC_DEFAULT_HASH_ENTRIES);
if (!mc)
return -ENOMEM;

ma = tbl_mask_array_alloc(MASK_ARRAY_SIZE_MIN);
Expand All @@ -367,6 +431,7 @@ int ovs_flow_tbl_init(struct flow_table *table)
rcu_assign_pointer(table->ti, ti);
rcu_assign_pointer(table->ufid_ti, ufid_ti);
rcu_assign_pointer(table->mask_array, ma);
rcu_assign_pointer(table->mask_cache, mc);
table->last_rehash = jiffies;
table->count = 0;
table->ufid_count = 0;
Expand All @@ -377,7 +442,7 @@ int ovs_flow_tbl_init(struct flow_table *table)
free_mask_array:
__mask_array_destroy(ma);
free_mask_cache:
free_percpu(table->mask_cache);
__mask_cache_destroy(mc);
return -ENOMEM;
}

Expand Down Expand Up @@ -453,9 +518,11 @@ void ovs_flow_tbl_destroy(struct flow_table *table)
{
struct table_instance *ti = rcu_dereference_raw(table->ti);
struct table_instance *ufid_ti = rcu_dereference_raw(table->ufid_ti);
struct mask_cache *mc = rcu_dereference(table->mask_cache);
struct mask_array *ma = rcu_dereference_ovsl(table->mask_array);

free_percpu(table->mask_cache);
call_rcu(&table->mask_array->rcu, mask_array_rcu_cb);
call_rcu(&mc->rcu, mask_cache_rcu_cb);
call_rcu(&ma->rcu, mask_array_rcu_cb);
table_instance_destroy(table, ti, ufid_ti, false);
}

Expand Down Expand Up @@ -724,6 +791,7 @@ struct sw_flow *ovs_flow_tbl_lookup_stats(struct flow_table *tbl,
u32 *n_mask_hit,
u32 *n_cache_hit)
{
struct mask_cache *mc = rcu_dereference(tbl->mask_cache);
struct mask_array *ma = rcu_dereference(tbl->mask_array);
struct table_instance *ti = rcu_dereference(tbl->ti);
struct mask_cache_entry *entries, *ce;
Expand All @@ -733,7 +801,7 @@ struct sw_flow *ovs_flow_tbl_lookup_stats(struct flow_table *tbl,

*n_mask_hit = 0;
*n_cache_hit = 0;
if (unlikely(!skb_hash)) {
if (unlikely(!skb_hash || mc->cache_size == 0)) {
u32 mask_index = 0;
u32 cache = 0;

Expand All @@ -749,11 +817,11 @@ struct sw_flow *ovs_flow_tbl_lookup_stats(struct flow_table *tbl,

ce = NULL;
hash = skb_hash;
entries = this_cpu_ptr(tbl->mask_cache);
entries = this_cpu_ptr(mc->mask_cache);

/* Find the cache entry 'ce' to operate on. */
for (seg = 0; seg < MC_HASH_SEGS; seg++) {
int index = hash & (MC_HASH_ENTRIES - 1);
int index = hash & (mc->cache_size - 1);
struct mask_cache_entry *e;

e = &entries[index];
Expand Down Expand Up @@ -867,6 +935,13 @@ int ovs_flow_tbl_num_masks(const struct flow_table *table)
return READ_ONCE(ma->count);
}

u32 ovs_flow_tbl_masks_cache_size(const struct flow_table *table)
{
struct mask_cache *mc = rcu_dereference(table->mask_cache);

return READ_ONCE(mc->cache_size);
}

static struct table_instance *table_instance_expand(struct table_instance *ti,
bool ufid)
{
Expand Down Expand Up @@ -1095,8 +1170,8 @@ void ovs_flow_masks_rebalance(struct flow_table *table)
for (i = 0; i < masks_entries; i++) {
int index = masks_and_count[i].index;

new->masks[new->count++] =
rcu_dereference_ovsl(ma->masks[index]);
if (ovsl_dereference(ma->masks[index]))
new->masks[new->count++] = ma->masks[index];
}

rcu_assign_pointer(table->mask_array, new);
Expand Down
10 changes: 9 additions & 1 deletion net/openvswitch/flow_table.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -27,6 +27,12 @@ struct mask_cache_entry {
u32 mask_index;
};

struct mask_cache {
struct rcu_head rcu;
u32 cache_size; /* Must be ^2 value. */
struct mask_cache_entry __percpu *mask_cache;
};

struct mask_count {
int index;
u64 counter;
Expand All @@ -53,7 +59,7 @@ struct table_instance {
struct flow_table {
struct table_instance __rcu *ti;
struct table_instance __rcu *ufid_ti;
struct mask_cache_entry __percpu *mask_cache;
struct mask_cache __rcu *mask_cache;
struct mask_array __rcu *mask_array;
unsigned long last_rehash;
unsigned int count;
Expand All @@ -77,6 +83,8 @@ int ovs_flow_tbl_insert(struct flow_table *table, struct sw_flow *flow,
const struct sw_flow_mask *mask);
void ovs_flow_tbl_remove(struct flow_table *table, struct sw_flow *flow);
int ovs_flow_tbl_num_masks(const struct flow_table *table);
u32 ovs_flow_tbl_masks_cache_size(const struct flow_table *table);
int ovs_flow_tbl_masks_cache_resize(struct flow_table *table, u32 size);
struct sw_flow *ovs_flow_tbl_dump_next(struct table_instance *table,
u32 *bucket, u32 *idx);
struct sw_flow *ovs_flow_tbl_lookup_stats(struct flow_table *,
Expand Down

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