mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-26 19:00:25 +00:00
![Kirill A. Shutemov](/assets/img/avatar_default.png)
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>
100 lines
2 KiB
C
100 lines
2 KiB
C
#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);
|