Hi,
Maybe this should really be an RFC, given that I don't fully understand
why the compaction_test.c program was mmap'ing 1 MB at a time. So
apologies in advance if I've mucked up something important, but if so,
maybe we can still find a way to get this fixed up to something better.
Anyway: there are 20+ tests in tools/testing/selftests/vm/. The entire
running time for these (via run_vmtest.sh) is about 56 seconds, of which
over half is due to just one test: compaction_test, which takes 27 sec!
(A runner-up is HMM, at 11 sec, so it's up for a look next.) The other
tests mostly take a few ms, and a few take 1.0 sec.
This drops the compaction_test run time from 27, to 3.3 sec. Enjoy. :)
thanks,
John Hubbard
NVIDIA
John Hubbard (1):
selftests/vm: 8x compaction_test speedup
tools/testing/selftests/vm/compaction_test.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
--
2.28.0
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 <[email protected]>
---
tools/testing/selftests/vm/compaction_test.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
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) {
--
2.28.0
On Fri, 2 Oct 2020 01:06:21 -0700 John Hubbard <[email protected]> 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" <[email protected]> wrote:
On Fri, 2 Oct 2020 01:06:21 -0700 John Hubbard <[email protected]> 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