| Message ID | 20201002080621.551044-2-jhubbard@nvidia.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | selftests/vm: 8x compaction_test speedup | expand |
On Fri, 2 Oct 2020 01:06:21 -0700 John Hubbard <jhubbard@nvidia.com> wrote: > This patch reduces the running time for compaction_test from about 27 > sec, to 3.3 sec, which is about an 8x speedup. > > These numbers are for an Intel x86_64 system with 32 GB of DRAM. > > The compaction_test.c program was spending most of its time doing > mmap(), 1 MB at a time, on about 25 GB of memory. > > Instead, do the mmaps 100 MB at a time. (Going past 100 MB doesn't make > things go much faster, because other parts of the program are using the > remaining time.) Seems nice. It's been 5 years, but hopefully Sri is still at Akamai? > --- a/tools/testing/selftests/vm/compaction_test.c > +++ b/tools/testing/selftests/vm/compaction_test.c > @@ -18,7 +18,8 @@ > > #include "../kselftest.h" > > -#define MAP_SIZE 1048576 > +#define MAP_SIZE_MB 100 > +#define MAP_SIZE (MAP_SIZE_MB * 1024 * 1024) > > struct map_list { > void *map; > @@ -165,7 +166,7 @@ int main(int argc, char **argv) > void *map = NULL; > unsigned long mem_free = 0; > unsigned long hugepage_size = 0; > - unsigned long mem_fragmentable = 0; > + long mem_fragmentable_MB = 0; > > if (prereq() != 0) { > printf("Either the sysctl compact_unevictable_allowed is not\n" > @@ -190,9 +191,9 @@ int main(int argc, char **argv) > return -1; > } > > - mem_fragmentable = mem_free * 0.8 / 1024; > + mem_fragmentable_MB = mem_free * 0.8 / 1024; > > - while (mem_fragmentable > 0) { > + while (mem_fragmentable_MB > 0) { > map = mmap(NULL, MAP_SIZE, PROT_READ | PROT_WRITE, > MAP_ANONYMOUS | MAP_PRIVATE | MAP_LOCKED, -1, 0); > if (map == MAP_FAILED) > @@ -213,7 +214,7 @@ int main(int argc, char **argv) > for (i = 0; i < MAP_SIZE; i += page_size) > *(unsigned long *)(map + i) = (unsigned long)map + i; > > - mem_fragmentable--; > + mem_fragmentable_MB -= MAP_SIZE_MB; > } > > for (entry = list; entry != NULL; entry = entry->next) { > -- > 2.28.0 >
On 10/2/20, 6:05 PM, "Andrew Morton" <akpm@linux-foundation.org> wrote:
On Fri, 2 Oct 2020 01:06:21 -0700 John Hubbard <jhubbard@nvidia.com> wrote:
> This patch reduces the running time for compaction_test from about 27
> sec, to 3.3 sec, which is about an 8x speedup.
>
> These numbers are for an Intel x86_64 system with 32 GB of DRAM.
>
> The compaction_test.c program was spending most of its time doing
> mmap(), 1 MB at a time, on about 25 GB of memory.
>
> Instead, do the mmaps 100 MB at a time. (Going past 100 MB doesn't make
> things go much faster, because other parts of the program are using the
> remaining time.)
Seems nice. It's been 5 years, but hopefully Sri is still at Akamai?
Looks good to me.
Thanks
-Sri
diff --git a/tools/testing/selftests/vm/compaction_test.c b/tools/testing/selftests/vm/compaction_test.c index bcec71250873..9b420140ba2b 100644 --- a/tools/testing/selftests/vm/compaction_test.c +++ b/tools/testing/selftests/vm/compaction_test.c @@ -18,7 +18,8 @@ #include "../kselftest.h" -#define MAP_SIZE 1048576 +#define MAP_SIZE_MB 100 +#define MAP_SIZE (MAP_SIZE_MB * 1024 * 1024) struct map_list { void *map; @@ -165,7 +166,7 @@ int main(int argc, char **argv) void *map = NULL; unsigned long mem_free = 0; unsigned long hugepage_size = 0; - unsigned long mem_fragmentable = 0; + long mem_fragmentable_MB = 0; if (prereq() != 0) { printf("Either the sysctl compact_unevictable_allowed is not\n" @@ -190,9 +191,9 @@ int main(int argc, char **argv) return -1; } - mem_fragmentable = mem_free * 0.8 / 1024; + mem_fragmentable_MB = mem_free * 0.8 / 1024; - while (mem_fragmentable > 0) { + while (mem_fragmentable_MB > 0) { map = mmap(NULL, MAP_SIZE, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE | MAP_LOCKED, -1, 0); if (map == MAP_FAILED) @@ -213,7 +214,7 @@ int main(int argc, char **argv) for (i = 0; i < MAP_SIZE; i += page_size) *(unsigned long *)(map + i) = (unsigned long)map + i; - mem_fragmentable--; + mem_fragmentable_MB -= MAP_SIZE_MB; } for (entry = list; entry != NULL; entry = entry->next) {
This patch reduces the running time for compaction_test from about 27 sec, to 3.3 sec, which is about an 8x speedup. These numbers are for an Intel x86_64 system with 32 GB of DRAM. The compaction_test.c program was spending most of its time doing mmap(), 1 MB at a time, on about 25 GB of memory. Instead, do the mmaps 100 MB at a time. (Going past 100 MB doesn't make things go much faster, because other parts of the program are using the remaining time.) Signed-off-by: John Hubbard <jhubbard@nvidia.com> --- tools/testing/selftests/vm/compaction_test.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-)