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authorKirill A. Shutemov <kirill.shutemov@linux.intel.com>2017-11-17 15:31:22 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2017-11-17 16:10:04 -0800
commit64c349f4ae78723248c474531d0cbc524fc5ba77 (patch)
treeb8284ccb8224f9f4023d5b4c1caa6bc053a2c90f /mm/gup_benchmark.c
parent15df03c87983660a4d1eedb4541778592bd97684 (diff)
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: 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>
Diffstat (limited to 'mm/gup_benchmark.c')
-rw-r--r--mm/gup_benchmark.c100
1 files changed, 100 insertions, 0 deletions
diff --git a/mm/gup_benchmark.c b/mm/gup_benchmark.c
new file mode 100644
index 000000000000..5c8e2abeaa15
--- /dev/null
+++ b/mm/gup_benchmark.c
@@ -0,0 +1,100 @@
+#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);