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1100262037
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> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Sri Jayaramappa <sjayaram@akamai.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Mel Gorman <mgorman@techsingularity.net> Link: https://lkml.kernel.org/r/20201002080621.551044-2-jhubbard@nvidia.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
232 lines
5.2 KiB
C
232 lines
5.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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*
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* A test for the patch "Allow compaction of unevictable pages".
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* With this patch we should be able to allocate at least 1/4
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* of RAM in huge pages. Without the patch much less is
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* allocated.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <sys/mman.h>
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#include <sys/resource.h>
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#include <fcntl.h>
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#include <errno.h>
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#include <unistd.h>
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#include <string.h>
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#include "../kselftest.h"
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#define MAP_SIZE_MB 100
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#define MAP_SIZE (MAP_SIZE_MB * 1024 * 1024)
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struct map_list {
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void *map;
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struct map_list *next;
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};
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int read_memory_info(unsigned long *memfree, unsigned long *hugepagesize)
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{
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char buffer[256] = {0};
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char *cmd = "cat /proc/meminfo | grep -i memfree | grep -o '[0-9]*'";
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FILE *cmdfile = popen(cmd, "r");
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if (!(fgets(buffer, sizeof(buffer), cmdfile))) {
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perror("Failed to read meminfo\n");
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return -1;
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}
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pclose(cmdfile);
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*memfree = atoll(buffer);
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cmd = "cat /proc/meminfo | grep -i hugepagesize | grep -o '[0-9]*'";
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cmdfile = popen(cmd, "r");
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if (!(fgets(buffer, sizeof(buffer), cmdfile))) {
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perror("Failed to read meminfo\n");
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return -1;
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}
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pclose(cmdfile);
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*hugepagesize = atoll(buffer);
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return 0;
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}
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int prereq(void)
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{
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char allowed;
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int fd;
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fd = open("/proc/sys/vm/compact_unevictable_allowed",
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O_RDONLY | O_NONBLOCK);
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if (fd < 0) {
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perror("Failed to open\n"
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"/proc/sys/vm/compact_unevictable_allowed\n");
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return -1;
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}
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if (read(fd, &allowed, sizeof(char)) != sizeof(char)) {
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perror("Failed to read from\n"
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"/proc/sys/vm/compact_unevictable_allowed\n");
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close(fd);
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return -1;
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}
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close(fd);
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if (allowed == '1')
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return 0;
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return -1;
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}
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int check_compaction(unsigned long mem_free, unsigned int hugepage_size)
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{
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int fd;
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int compaction_index = 0;
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char initial_nr_hugepages[10] = {0};
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char nr_hugepages[10] = {0};
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/* We want to test with 80% of available memory. Else, OOM killer comes
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in to play */
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mem_free = mem_free * 0.8;
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fd = open("/proc/sys/vm/nr_hugepages", O_RDWR | O_NONBLOCK);
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if (fd < 0) {
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perror("Failed to open /proc/sys/vm/nr_hugepages");
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return -1;
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}
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if (read(fd, initial_nr_hugepages, sizeof(initial_nr_hugepages)) <= 0) {
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perror("Failed to read from /proc/sys/vm/nr_hugepages");
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goto close_fd;
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}
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/* Start with the initial condition of 0 huge pages*/
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if (write(fd, "0", sizeof(char)) != sizeof(char)) {
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perror("Failed to write 0 to /proc/sys/vm/nr_hugepages\n");
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goto close_fd;
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}
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lseek(fd, 0, SEEK_SET);
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/* Request a large number of huge pages. The Kernel will allocate
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as much as it can */
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if (write(fd, "100000", (6*sizeof(char))) != (6*sizeof(char))) {
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perror("Failed to write 100000 to /proc/sys/vm/nr_hugepages\n");
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goto close_fd;
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}
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lseek(fd, 0, SEEK_SET);
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if (read(fd, nr_hugepages, sizeof(nr_hugepages)) <= 0) {
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perror("Failed to re-read from /proc/sys/vm/nr_hugepages\n");
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goto close_fd;
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}
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/* We should have been able to request at least 1/3 rd of the memory in
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huge pages */
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compaction_index = mem_free/(atoi(nr_hugepages) * hugepage_size);
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if (compaction_index > 3) {
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printf("No of huge pages allocated = %d\n",
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(atoi(nr_hugepages)));
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fprintf(stderr, "ERROR: Less that 1/%d of memory is available\n"
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"as huge pages\n", compaction_index);
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goto close_fd;
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}
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printf("No of huge pages allocated = %d\n",
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(atoi(nr_hugepages)));
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lseek(fd, 0, SEEK_SET);
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if (write(fd, initial_nr_hugepages, strlen(initial_nr_hugepages))
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!= strlen(initial_nr_hugepages)) {
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perror("Failed to write value to /proc/sys/vm/nr_hugepages\n");
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goto close_fd;
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}
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close(fd);
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return 0;
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close_fd:
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close(fd);
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printf("Not OK. Compaction test failed.");
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return -1;
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}
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int main(int argc, char **argv)
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{
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struct rlimit lim;
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struct map_list *list, *entry;
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size_t page_size, i;
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void *map = NULL;
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unsigned long mem_free = 0;
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unsigned long hugepage_size = 0;
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long mem_fragmentable_MB = 0;
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if (prereq() != 0) {
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printf("Either the sysctl compact_unevictable_allowed is not\n"
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"set to 1 or couldn't read the proc file.\n"
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"Skipping the test\n");
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return KSFT_SKIP;
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}
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lim.rlim_cur = RLIM_INFINITY;
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lim.rlim_max = RLIM_INFINITY;
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if (setrlimit(RLIMIT_MEMLOCK, &lim)) {
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perror("Failed to set rlimit:\n");
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return -1;
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}
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page_size = getpagesize();
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list = NULL;
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if (read_memory_info(&mem_free, &hugepage_size) != 0) {
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printf("ERROR: Cannot read meminfo\n");
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return -1;
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}
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mem_fragmentable_MB = mem_free * 0.8 / 1024;
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while (mem_fragmentable_MB > 0) {
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map = mmap(NULL, MAP_SIZE, PROT_READ | PROT_WRITE,
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MAP_ANONYMOUS | MAP_PRIVATE | MAP_LOCKED, -1, 0);
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if (map == MAP_FAILED)
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break;
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entry = malloc(sizeof(struct map_list));
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if (!entry) {
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munmap(map, MAP_SIZE);
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break;
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}
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entry->map = map;
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entry->next = list;
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list = entry;
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/* Write something (in this case the address of the map) to
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* ensure that KSM can't merge the mapped pages
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*/
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for (i = 0; i < MAP_SIZE; i += page_size)
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*(unsigned long *)(map + i) = (unsigned long)map + i;
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mem_fragmentable_MB -= MAP_SIZE_MB;
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}
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for (entry = list; entry != NULL; entry = entry->next) {
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munmap(entry->map, MAP_SIZE);
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if (!entry->next)
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break;
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entry = entry->next;
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}
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if (check_compaction(mem_free, hugepage_size) == 0)
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return 0;
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return -1;
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}
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