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mm: add infrastructure for get_user_pages_fast() benchmarking

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Performance of get_user_pages_fast() is critical for some workloads, but
it's tricky to test it directly.

This patch provides /sys/kernel/debug/gup_benchmark that helps with
testing performance of it.

See tools/testing/selftests/vm/gup_benchmark.c for userspace
counterpart.

Link: http://lkml.kernel.org/r/20170908215603.9189-2-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thorsten Leemhuis <regressions@leemhuis.info>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Huang Ying <ying.huang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Kirill A. Shutemov
2017-11-17 15:31:22 -08:00
committed by Linus Torvalds
parent 15df03c879
commit 64c349f4ae
5 changed files with 202 additions and 0 deletions
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1
tools/testing/selftests/vm/Makefile
View File

@@ -18,6 +18,7 @@ TEST_GEN_FILES += transhuge-stress
TEST_GEN_FILES += userfaultfd
TEST_GEN_FILES += mlock-random-test
TEST_GEN_FILES += virtual_address_range
TEST_GEN_FILES += gup_benchmark
TEST_PROGS := run_vmtests

91
tools/testing/selftests/vm/gup_benchmark.c Normal file
View File

@@ -0,0 +1,91 @@
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sys/prctl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <linux/types.h>
#define MB (1UL << 20)
#define PAGE_SIZE sysconf(_SC_PAGESIZE)
#define GUP_FAST_BENCHMARK _IOWR('g', 1, struct gup_benchmark)
struct gup_benchmark {
__u64 delta_usec;
__u64 addr;
__u64 size;
__u32 nr_pages_per_call;
__u32 flags;
};
int main(int argc, char **argv)
{
struct gup_benchmark gup;
unsigned long size = 128 * MB;
int i, fd, opt, nr_pages = 1, thp = -1, repeats = 1, write = 0;
char *p;
while ((opt = getopt(argc, argv, "m:r:n:tT")) != -1) {
switch (opt) {
case 'm':
size = atoi(optarg) * MB;
break;
case 'r':
repeats = atoi(optarg);
break;
case 'n':
nr_pages = atoi(optarg);
break;
case 't':
thp = 1;
break;
case 'T':
thp = 0;
break;
case 'w':
write = 1;
default:
return -1;
}
}
gup.nr_pages_per_call = nr_pages;
gup.flags = write;
fd = open("/sys/kernel/debug/gup_benchmark", O_RDWR);
if (fd == -1)
perror("open"), exit(1);
p = mmap(NULL, size, PROT_READ | PROT_WRITE,
MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
if (p == MAP_FAILED)
perror("mmap"), exit(1);
gup.addr = (unsigned long)p;
if (thp == 1)
madvise(p, size, MADV_HUGEPAGE);
else if (thp == 0)
madvise(p, size, MADV_NOHUGEPAGE);
for (; (unsigned long)p < gup.addr + size; p += PAGE_SIZE)
p[0] = 0;
for (i = 0; i < repeats; i++) {
gup.size = size;
if (ioctl(fd, GUP_FAST_BENCHMARK, &gup))
perror("ioctl"), exit(1);
printf("Time: %lld us", gup.delta_usec);
if (gup.size != size)
printf(", truncated (size: %lld)", gup.size);
printf("\n");
}
return 0;
}