Commit 64c349f4 authored by Kirill A. Shutemov's avatar Kirill A. Shutemov Committed by Linus Torvalds

mm: add infrastructure for get_user_pages_fast() benchmarking

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.comSigned-off-by: default avatarKirill 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 15df03c8
......@@ -756,3 +756,12 @@ config PERCPU_STATS
This feature collects and exposes statistics via debugfs. The
information includes global and per chunk statistics, which can
be used to help understand percpu memory usage.
config GUP_BENCHMARK
bool "Enable infrastructure for get_user_pages_fast() benchmarking"
default n
help
Provides /sys/kernel/debug/gup_benchmark that helps with testing
performance of get_user_pages_fast().
See tools/testing/selftests/vm/gup_benchmark.c
......@@ -80,6 +80,7 @@ obj-$(CONFIG_PAGE_COUNTER) += page_counter.o
obj-$(CONFIG_MEMCG) += memcontrol.o vmpressure.o
obj-$(CONFIG_MEMCG_SWAP) += swap_cgroup.o
obj-$(CONFIG_CGROUP_HUGETLB) += hugetlb_cgroup.o
obj-$(CONFIG_GUP_BENCHMARK) += gup_benchmark.o
obj-$(CONFIG_MEMORY_FAILURE) += memory-failure.o
obj-$(CONFIG_HWPOISON_INJECT) += hwpoison-inject.o
obj-$(CONFIG_DEBUG_KMEMLEAK) += kmemleak.o
......
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/ktime.h>
#include <linux/debugfs.h>
#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;
};
static int __gup_benchmark_ioctl(unsigned int cmd,
struct gup_benchmark *gup)
{
ktime_t start_time, end_time;
unsigned long i, nr, nr_pages, addr, next;
struct page **pages;
nr_pages = gup->size / PAGE_SIZE;
pages = kvmalloc(sizeof(void *) * nr_pages, GFP_KERNEL);
if (!pages)
return -ENOMEM;
i = 0;
nr = gup->nr_pages_per_call;
start_time = ktime_get();
for (addr = gup->addr; addr < gup->addr + gup->size; addr = next) {
if (nr != gup->nr_pages_per_call)
break;
next = addr + nr * PAGE_SIZE;
if (next > gup->addr + gup->size) {
next = gup->addr + gup->size;
nr = (next - addr) / PAGE_SIZE;
}
nr = get_user_pages_fast(addr, nr, gup->flags & 1, pages + i);
i += nr;
}
end_time = ktime_get();
gup->delta_usec = ktime_us_delta(end_time, start_time);
gup->size = addr - gup->addr;
for (i = 0; i < nr_pages; i++) {
if (!pages[i])
break;
put_page(pages[i]);
}
kvfree(pages);
return 0;
}
static long gup_benchmark_ioctl(struct file *filep, unsigned int cmd,
unsigned long arg)
{
struct gup_benchmark gup;
int ret;
if (cmd != GUP_FAST_BENCHMARK)
return -EINVAL;
if (copy_from_user(&gup, (void __user *)arg, sizeof(gup)))
return -EFAULT;
ret = __gup_benchmark_ioctl(cmd, &gup);
if (ret)
return ret;
if (copy_to_user((void __user *)arg, &gup, sizeof(gup)))
return -EFAULT;
return 0;
}
static const struct file_operations gup_benchmark_fops = {
.open = nonseekable_open,
.unlocked_ioctl = gup_benchmark_ioctl,
};
static int gup_benchmark_init(void)
{
void *ret;
ret = debugfs_create_file_unsafe("gup_benchmark", 0600, NULL, NULL,
&gup_benchmark_fops);
if (!ret)
pr_warn("Failed to create gup_benchmark in debugfs");
return 0;
}
late_initcall(gup_benchmark_init);
......@@ -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
......
#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;
}
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment