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

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.com


Signed-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

mm/Kconfig

+9 −0
Original line number Diff line number Diff line
@@ -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

mm/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -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

mm/gup_benchmark.c

0 → 100644
+100 −0
Original line number Diff line number Diff line 
#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);

tools/testing/selftests/vm/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -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

tools/testing/selftests/vm/gup_benchmark.c

0 → 100644
+91 −0
Original line number Diff line number Diff line 
#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;

}