From bd67d5c15cc190f52eb2f2a2f6f6b800ca33d9dd Mon Sep 17 00:00:00 2001 From: Sri Jayaramappa Date: Thu, 23 Apr 2015 14:21:41 -0400 Subject: [PATCH] Test compaction of mlocked memory Commit commit 5bbe3547aa3b ("mm: allow compaction of unevictable pages") introduced a sysctl that allows userspace to enable scanning of locked pages for compaction. This patch introduces a new test which fragments main memory and attempts to allocate a number of huge pages to exercise this compaction logic. Tested on machines with up to 32 GB RAM. With the patch a much larger number of huge pages can be allocated than on the kernel without the patch. Example output: On a machine with 16 GB RAM: sudo make run_tests vm ... ----------------------- running compaction_test ----------------------- No of huge pages allocated = 3834 [PASS] ... Signed-off-by: Sri Jayaramappa Cc: linux-kernel@vger.kernel.org Cc: linux-api@vger.kernel.org Cc: Andrew Morton Cc: Eric B Munson Reviewed-by: Eric B Munson Acked-by: Andrew Morton Signed-off-by: Shuah Khan --- tools/testing/selftests/vm/Makefile | 7 +- tools/testing/selftests/vm/compaction_test.c | 225 +++++++++++++++++++ tools/testing/selftests/vm/run_vmtests | 12 + 3 files changed, 243 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/vm/compaction_test.c diff --git a/tools/testing/selftests/vm/Makefile b/tools/testing/selftests/vm/Makefile index a5ce9534eb15..231b9a031f6a 100644 --- a/tools/testing/selftests/vm/Makefile +++ b/tools/testing/selftests/vm/Makefile @@ -1,7 +1,12 @@ # Makefile for vm selftests CFLAGS = -Wall -BINARIES = hugepage-mmap hugepage-shm map_hugetlb thuge-gen hugetlbfstest +BINARIES = compaction_test +BINARIES += hugepage-mmap +BINARIES += hugepage-shm +BINARIES += hugetlbfstest +BINARIES += map_hugetlb +BINARIES += thuge-gen BINARIES += transhuge-stress all: $(BINARIES) diff --git a/tools/testing/selftests/vm/compaction_test.c b/tools/testing/selftests/vm/compaction_test.c new file mode 100644 index 000000000000..932ff577ffc0 --- /dev/null +++ b/tools/testing/selftests/vm/compaction_test.c @@ -0,0 +1,225 @@ +/* + * + * A test for the patch "Allow compaction of unevictable pages". + * With this patch we should be able to allocate at least 1/4 + * of RAM in huge pages. Without the patch much less is + * allocated. + */ + +#include +#include +#include +#include +#include +#include +#include +#include + +#define MAP_SIZE 1048576 + +struct map_list { + void *map; + struct map_list *next; +}; + +int read_memory_info(unsigned long *memfree, unsigned long *hugepagesize) +{ + char buffer[256] = {0}; + char *cmd = "cat /proc/meminfo | grep -i memfree | grep -o '[0-9]*'"; + FILE *cmdfile = popen(cmd, "r"); + + if (!(fgets(buffer, sizeof(buffer), cmdfile))) { + perror("Failed to read meminfo\n"); + return -1; + } + + pclose(cmdfile); + + *memfree = atoll(buffer); + cmd = "cat /proc/meminfo | grep -i hugepagesize | grep -o '[0-9]*'"; + cmdfile = popen(cmd, "r"); + + if (!(fgets(buffer, sizeof(buffer), cmdfile))) { + perror("Failed to read meminfo\n"); + return -1; + } + + pclose(cmdfile); + *hugepagesize = atoll(buffer); + + return 0; +} + +int prereq(void) +{ + char allowed; + int fd; + + fd = open("/proc/sys/vm/compact_unevictable_allowed", + O_RDONLY | O_NONBLOCK); + if (fd < 0) { + perror("Failed to open\n" + "/proc/sys/vm/compact_unevictable_allowed\n"); + return -1; + } + + if (read(fd, &allowed, sizeof(char)) != sizeof(char)) { + perror("Failed to read from\n" + "/proc/sys/vm/compact_unevictable_allowed\n"); + close(fd); + return -1; + } + + close(fd); + if (allowed == '1') + return 0; + + return -1; +} + +int check_compaction(unsigned long mem_free, unsigned int hugepage_size) +{ + int fd; + int compaction_index = 0; + char initial_nr_hugepages[10] = {0}; + char nr_hugepages[10] = {0}; + + /* We want to test with 80% of available memory. Else, OOM killer comes + in to play */ + mem_free = mem_free * 0.8; + + fd = open("/proc/sys/vm/nr_hugepages", O_RDWR | O_NONBLOCK); + if (fd < 0) { + perror("Failed to open /proc/sys/vm/nr_hugepages"); + return -1; + } + + if (read(fd, initial_nr_hugepages, sizeof(initial_nr_hugepages)) <= 0) { + perror("Failed to read from /proc/sys/vm/nr_hugepages"); + goto close_fd; + } + + /* Start with the initial condition of 0 huge pages*/ + if (write(fd, "0", sizeof(char)) != sizeof(char)) { + perror("Failed to write to /proc/sys/vm/nr_hugepages\n"); + goto close_fd; + } + + lseek(fd, 0, SEEK_SET); + + /* Request a large number of huge pages. The Kernel will allocate + as much as it can */ + if (write(fd, "100000", (6*sizeof(char))) != (6*sizeof(char))) { + perror("Failed to write to /proc/sys/vm/nr_hugepages\n"); + goto close_fd; + } + + lseek(fd, 0, SEEK_SET); + + if (read(fd, nr_hugepages, sizeof(nr_hugepages)) <= 0) { + perror("Failed to read from /proc/sys/vm/nr_hugepages\n"); + goto close_fd; + } + + /* We should have been able to request at least 1/3 rd of the memory in + huge pages */ + compaction_index = mem_free/(atoi(nr_hugepages) * hugepage_size); + + if (compaction_index > 3) { + printf("No of huge pages allocated = %d\n", + (atoi(nr_hugepages))); + fprintf(stderr, "ERROR: Less that 1/%d of memory is available\n" + "as huge pages\n", compaction_index); + goto close_fd; + } + + printf("No of huge pages allocated = %d\n", + (atoi(nr_hugepages))); + + if (write(fd, initial_nr_hugepages, sizeof(initial_nr_hugepages)) + != strlen(initial_nr_hugepages)) { + perror("Failed to write to /proc/sys/vm/nr_hugepages\n"); + goto close_fd; + } + + close(fd); + return 0; + + close_fd: + close(fd); + printf("Not OK. Compaction test failed."); + return -1; +} + + +int main(int argc, char **argv) +{ + struct rlimit lim; + struct map_list *list, *entry; + size_t page_size, i; + void *map = NULL; + unsigned long mem_free = 0; + unsigned long hugepage_size = 0; + unsigned long mem_fragmentable = 0; + + if (prereq() != 0) { + printf("Either the sysctl compact_unevictable_allowed is not\n" + "set to 1 or couldn't read the proc file.\n" + "Skipping the test\n"); + return 0; + } + + lim.rlim_cur = RLIM_INFINITY; + lim.rlim_max = RLIM_INFINITY; + if (setrlimit(RLIMIT_MEMLOCK, &lim)) { + perror("Failed to set rlimit:\n"); + return -1; + } + + page_size = getpagesize(); + + list = NULL; + + if (read_memory_info(&mem_free, &hugepage_size) != 0) { + printf("ERROR: Cannot read meminfo\n"); + return -1; + } + + mem_fragmentable = mem_free * 0.8 / 1024; + + while (mem_fragmentable > 0) { + map = mmap(NULL, MAP_SIZE, PROT_READ | PROT_WRITE, + MAP_ANONYMOUS | MAP_PRIVATE | MAP_LOCKED, -1, 0); + if (map == MAP_FAILED) + break; + + entry = malloc(sizeof(struct map_list)); + if (!entry) { + munmap(map, MAP_SIZE); + break; + } + entry->map = map; + entry->next = list; + list = entry; + + /* Write something (in this case the address of the map) to + * ensure that KSM can't merge the mapped pages + */ + for (i = 0; i < MAP_SIZE; i += page_size) + *(unsigned long *)(map + i) = (unsigned long)map + i; + + mem_fragmentable--; + } + + for (entry = list; entry != NULL; entry = entry->next) { + munmap(entry->map, MAP_SIZE); + if (!entry->next) + break; + entry = entry->next; + } + + if (check_compaction(mem_free, hugepage_size) == 0) + return 0; + + return -1; +} diff --git a/tools/testing/selftests/vm/run_vmtests b/tools/testing/selftests/vm/run_vmtests index c87b6812300d..49ece11ff7fd 100755 --- a/tools/testing/selftests/vm/run_vmtests +++ b/tools/testing/selftests/vm/run_vmtests @@ -90,4 +90,16 @@ fi umount $mnt rm -rf $mnt echo $nr_hugepgs > /proc/sys/vm/nr_hugepages + +echo "-----------------------" +echo "running compaction_test" +echo "-----------------------" +./compaction_test +if [ $? -ne 0 ]; then + echo "[FAIL]" + exitcode=1 +else + echo "[PASS]" +fi + exit $exitcode -- 2.39.5