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