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samples/bpf: xdpsock: Add sched policy and priority support
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By default, TX schedule policy is SCHED_OTHER (round-robin time-sharing).
To improve TX cyclic scheduling, we add SCHED_FIFO policy and its priority
by using -W FIFO or --policy=FIFO and -U <PRIO> or --schpri=<PRIO>.

A) From xdpsock --app-stats, for SCHED_OTHER policy:
   $ xdpsock -i eth0 -t -N -z -T 1000 -b 16 -C 100000 -a

                      period     min        ave        max        cycle
   Cyclic TX          1000000    53507      75334      712642     6250

B) For SCHED_FIFO policy and schpri=50:
   $ xdpsock -i eth0 -t -N -z -T 1000 -b 16 -C 100000 -a -W FIFO -U 50

                      period     min        ave        max        cycle
   Cyclic TX          1000000    3699       24859      54397      6250

Signed-off-by: Ong Boon Leong <boon.leong.ong@intel.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211230035447.523177-6-boon.leong.ong@intel.com
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Ong Boon Leong authored and Alexei Starovoitov committed Jan 6, 2022
1 parent fa0d27a commit fa24d0b
Showing 1 changed file with 59 additions and 2 deletions.
61 changes: 59 additions & 2 deletions samples/bpf/xdpsock_user.c
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Original file line number Diff line number Diff line change
Expand Up @@ -31,6 +31,7 @@
#include <sys/un.h>
#include <time.h>
#include <unistd.h>
#include <sched.h>

#include <bpf/libbpf.h>
#include <bpf/xsk.h>
Expand Down Expand Up @@ -66,6 +67,8 @@
#define NSEC_PER_SEC 1000000000UL
#define NSEC_PER_USEC 1000

#define SCHED_PRI__DEFAULT 0

typedef __u64 u64;
typedef __u32 u32;
typedef __u16 u16;
Expand Down Expand Up @@ -123,6 +126,8 @@ static bool opt_busy_poll;
static bool opt_reduced_cap;
static clockid_t opt_clock = CLOCK_MONOTONIC;
static unsigned long opt_tx_cycle_ns;
static int opt_schpolicy = SCHED_OTHER;
static int opt_schprio = SCHED_PRI__DEFAULT;

struct vlan_ethhdr {
unsigned char h_dest[6];
Expand Down Expand Up @@ -198,6 +203,15 @@ static const struct clockid_map {
{ NULL }
};

static const struct sched_map {
const char *name;
int policy;
} schmap[] = {
{ "OTHER", SCHED_OTHER },
{ "FIFO", SCHED_FIFO },
{ NULL }
};

static int num_socks;
struct xsk_socket_info *xsks[MAX_SOCKS];
int sock;
Expand All @@ -216,6 +230,20 @@ static int get_clockid(clockid_t *id, const char *name)
return -1;
}

static int get_schpolicy(int *policy, const char *name)
{
const struct sched_map *sch;

for (sch = schmap; sch->name; sch++) {
if (strcasecmp(sch->name, name) == 0) {
*policy = sch->policy;
return 0;
}
}

return -1;
}

static unsigned long get_nsecs(void)
{
struct timespec ts;
Expand Down Expand Up @@ -1019,6 +1047,8 @@ static struct option long_options[] = {
{"tx-dmac", required_argument, 0, 'G'},
{"tx-smac", required_argument, 0, 'H'},
{"tx-cycle", required_argument, 0, 'T'},
{"policy", required_argument, 0, 'W'},
{"schpri", required_argument, 0, 'U'},
{"extra-stats", no_argument, 0, 'x'},
{"quiet", no_argument, 0, 'Q'},
{"app-stats", no_argument, 0, 'a'},
Expand Down Expand Up @@ -1066,6 +1096,8 @@ static void usage(const char *prog)
" -G, --tx-dmac=<MAC> Dest MAC addr of TX frame in aa:bb:cc:dd:ee:ff format (For -V|--tx-vlan)\n"
" -H, --tx-smac=<MAC> Src MAC addr of TX frame in aa:bb:cc:dd:ee:ff format (For -V|--tx-vlan)\n"
" -T, --tx-cycle=n Tx cycle time in micro-seconds (For -t|--txonly).\n"
" -W, --policy=POLICY Schedule policy. Default: SCHED_OTHER\n"
" -U, --schpri=n Schedule priority. Default: %d\n"
" -x, --extra-stats Display extra statistics.\n"
" -Q, --quiet Do not display any stats.\n"
" -a, --app-stats Display application (syscall) statistics.\n"
Expand All @@ -1076,7 +1108,8 @@ static void usage(const char *prog)
fprintf(stderr, str, prog, XSK_UMEM__DEFAULT_FRAME_SIZE,
opt_batch_size, MIN_PKT_SIZE, MIN_PKT_SIZE,
XSK_UMEM__DEFAULT_FRAME_SIZE, opt_pkt_fill_pattern,
VLAN_VID__DEFAULT, VLAN_PRI__DEFAULT);
VLAN_VID__DEFAULT, VLAN_PRI__DEFAULT,
SCHED_PRI__DEFAULT);

exit(EXIT_FAILURE);
}
Expand All @@ -1088,7 +1121,8 @@ static void parse_command_line(int argc, char **argv)
opterr = 0;

for (;;) {
c = getopt_long(argc, argv, "Frtli:q:pSNn:w:czf:muMd:b:C:s:P:VJ:K:G:H:T:xQaI:BR",
c = getopt_long(argc, argv,
"Frtli:q:pSNn:w:czf:muMd:b:C:s:P:VJ:K:G:H:T:W:U:xQaI:BR",
long_options, &option_index);
if (c == -1)
break;
Expand Down Expand Up @@ -1206,6 +1240,17 @@ static void parse_command_line(int argc, char **argv)
opt_tx_cycle_ns = atoi(optarg);
opt_tx_cycle_ns *= NSEC_PER_USEC;
break;
case 'W':
if (get_schpolicy(&opt_schpolicy, optarg)) {
fprintf(stderr,
"ERROR: Invalid policy %s. Default to SCHED_OTHER.\n",
optarg);
opt_schpolicy = SCHED_OTHER;
}
break;
case 'U':
opt_schprio = atoi(optarg);
break;
case 'x':
opt_extra_stats = 1;
break;
Expand Down Expand Up @@ -1780,6 +1825,7 @@ int main(int argc, char **argv)
struct __user_cap_data_struct data[2] = { { 0 } };
struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
bool rx = false, tx = false;
struct sched_param schparam;
struct xsk_umem_info *umem;
struct bpf_object *obj;
int xsks_map_fd = 0;
Expand Down Expand Up @@ -1881,13 +1927,24 @@ int main(int argc, char **argv)
prev_time = get_nsecs();
start_time = prev_time;

/* Configure sched priority for better wake-up accuracy */
memset(&schparam, 0, sizeof(schparam));
schparam.sched_priority = opt_schprio;
ret = sched_setscheduler(0, opt_schpolicy, &schparam);
if (ret) {
fprintf(stderr, "Error(%d) in setting priority(%d): %s\n",
errno, opt_schprio, strerror(errno));
goto out;
}

if (opt_bench == BENCH_RXDROP)
rx_drop_all();
else if (opt_bench == BENCH_TXONLY)
tx_only_all();
else
l2fwd_all();

out:
benchmark_done = true;

if (!opt_quiet)
Expand Down

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