prior to 2.6.21 i could "numactl --interleave=all" and use SHM_HUGETLB and
the interleave policy would be respected. as of 2.6.21 it doesn't seem to
respect the policy on SHM_HUGETLB request.
see test program below.
output from pre-2.6.21:
2ab196200000 interleave=0-3 file=/2\040(deleted) huge dirty=32 N0=8 N1=8 N2=8 N3=8
2ab19a200000 default file=/SYSV00000000\040(deleted) dirty=16384 active=0 N0=4096 N1=4096 N2=4096 N3=4096
output from 2.6.21:
2b49b1c00000 default file=/10\040(deleted) huge dirty=32 N3=32
2b49b5c00000 default file=/SYSV00000000\040(deleted) dirty=16384 active=0 N0=4096 N1=4096 N2=4096 N3=4096
was this an intentional behaviour change? it seems to be only affecting
SHM_HUGETLB allocations. (i haven't tested hugetlbfs yet.)
run with "numactl --interleave=all ./shmtest"
-dean
/* shmtest.c */
#include <sys/mman.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
static void *alloc_arena_shm(size_t arena_size, unsigned flags)
{
FILE *fh;
char buf[512];
size_t huge_page_size;
char *p;
int shmid;
void *arena;
// find Hugepagesize in /proc/meminfo
if ((fh = fopen("/proc/meminfo", "r")) == NULL) {
perror("open(/proc/meminfo)");
exit(1);
}
for (;;) {
if (fgets(buf, sizeof(buf)-1, fh) == NULL) {
fprintf(stderr, "didn't find Hugepagesize in /proc/meminfo");
exit(1);
}
buf[sizeof(buf)-1] = '\0';
if (strncmp(buf, "Hugepagesize:", 13) == 0) break;
}
p = strchr(buf, ':') + 1;
huge_page_size = strtoul(p, 0, 0) * 1024;
fclose(fh);
// round the size up to multiple of huge_page_size
arena_size = (arena_size + huge_page_size - 1) & ~(huge_page_size - 1);
shmid = shmget(IPC_PRIVATE, arena_size, IPC_CREAT|IPC_EXCL|flags|0600);
if (shmid == -1) {
perror("shmget");
exit(1);
}
arena = shmat(shmid, NULL, 0);
if (arena == (void *)-1) {
perror("shmat");
exit(1);
}
if (shmctl(shmid, IPC_RMID, 0) == -1) {
perror("shmctl warning");
}
return arena;
}
int main(int argc, char **argv)
{
char buf[1024];
const size_t sz = 64*1024*1024;
void *arena = alloc_arena_shm(sz, SHM_HUGETLB);
memset(arena, 0, sz);
snprintf(buf, sizeof(buf), "grep ^%llx /proc/%d/numa_maps", (unsigned long long)arena, (int)getpid());
system(buf);
arena = alloc_arena_shm(sz, 0);
memset(arena, 0, sz);
snprintf(buf, sizeof(buf), "grep ^%llx /proc/%d/numa_maps", (unsigned long long)arena, (int)getpid());
system(buf);
return 0;
}
-
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