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authorPavel Tatashin <pasha.tatashin@soleen.com>2021-05-05 04:39:27 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2021-05-05 21:27:26 +0300
commite44605a8b1aa13d892addc59ec3d416cb186c77b (patch)
tree7de4af91e0ed03cb42404622874128a037afb444 /tools
parent79dbf135e2481eaa77b172d88c343bf85e021545 (diff)
downloadlinux-e44605a8b1aa13d892addc59ec3d416cb186c77b.tar.xz
selftests/vm: gup_test: test faulting in kernel, and verify pinnable pages
When pages are pinned they can be faulted in userland and migrated, and they can be faulted right in kernel without migration. In either case, the pinned pages must end-up being pinnable (not movable). Add a new test to gup_test, to help verify that the gup/pup (get_user_pages() / pin_user_pages()) behavior with respect to pinnable and movable pages is reasonable and correct. Specifically, provide a way to: 1) Verify that only "pinnable" pages are pinned. This is checked automatically for you. 2) Verify that gup/pup performance is reasonable. This requires comparing benchmarks between doing gup/pup on pages that have been pre-faulted in from user space, vs. doing gup/pup on pages that are not faulted in until gup/pup time (via FOLL_TOUCH). This decision is controlled with the new -z command line option. Link: https://lkml.kernel.org/r/20210215161349.246722-15-pasha.tatashin@soleen.com Signed-off-by: Pavel Tatashin <pasha.tatashin@soleen.com> Reviewed-by: John Hubbard <jhubbard@nvidia.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Ira Weiny <ira.weiny@intel.com> Cc: James Morris <jmorris@namei.org> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sasha Levin <sashal@kernel.org> Cc: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Tyler Hicks <tyhicks@linux.microsoft.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'tools')
-rw-r--r--tools/testing/selftests/vm/gup_test.c23
1 files changed, 19 insertions, 4 deletions
diff --git a/tools/testing/selftests/vm/gup_test.c b/tools/testing/selftests/vm/gup_test.c
index 943cc2608dc2..1e662d59c502 100644
--- a/tools/testing/selftests/vm/gup_test.c
+++ b/tools/testing/selftests/vm/gup_test.c
@@ -13,6 +13,7 @@
/* Just the flags we need, copied from mm.h: */
#define FOLL_WRITE 0x01 /* check pte is writable */
+#define FOLL_TOUCH 0x02 /* mark page accessed */
static char *cmd_to_str(unsigned long cmd)
{
@@ -39,11 +40,11 @@ int main(int argc, char **argv)
unsigned long size = 128 * MB;
int i, fd, filed, opt, nr_pages = 1, thp = -1, repeats = 1, write = 1;
unsigned long cmd = GUP_FAST_BENCHMARK;
- int flags = MAP_PRIVATE;
+ int flags = MAP_PRIVATE, touch = 0;
char *file = "/dev/zero";
char *p;
- while ((opt = getopt(argc, argv, "m:r:n:F:f:abctTLUuwWSHp")) != -1) {
+ while ((opt = getopt(argc, argv, "m:r:n:F:f:abctTLUuwWSHpz")) != -1) {
switch (opt) {
case 'a':
cmd = PIN_FAST_BENCHMARK;
@@ -110,6 +111,10 @@ int main(int argc, char **argv)
case 'H':
flags |= (MAP_HUGETLB | MAP_ANONYMOUS);
break;
+ case 'z':
+ /* fault pages in gup, do not fault in userland */
+ touch = 1;
+ break;
default:
return -1;
}
@@ -167,8 +172,18 @@ int main(int argc, char **argv)
else if (thp == 0)
madvise(p, size, MADV_NOHUGEPAGE);
- for (; (unsigned long)p < gup.addr + size; p += PAGE_SIZE)
- p[0] = 0;
+ /*
+ * FOLL_TOUCH, in gup_test, is used as an either/or case: either
+ * fault pages in from the kernel via FOLL_TOUCH, or fault them
+ * in here, from user space. This allows comparison of performance
+ * between those two cases.
+ */
+ if (touch) {
+ gup.gup_flags |= FOLL_TOUCH;
+ } else {
+ for (; (unsigned long)p < gup.addr + size; p += PAGE_SIZE)
+ p[0] = 0;
+ }
/* Only report timing information on the *_BENCHMARK commands: */
if ((cmd == PIN_FAST_BENCHMARK) || (cmd == GUP_FAST_BENCHMARK) ||