[LTP] [PATCH v2] mem/oom: allocate memory using multiple threads

[Jan Stancek]

This is to make testcase faster on big systems, for example,
on Lenovo X3950 X6, 256GB RAM, 240 CPUs, 8 NUMA nodes
oom01 testcase would previously take ~4 hours to complete.
With this patch it takes ~16 minutes.

This change spawns CPU-1 (or at least 1) thread(s), which
allocate / fault-in memory in same way as before.

Signed-off-by: Jan Stancek <jstan...@redhat.com>
---
 testcases/kernel/mem/include/libmem.mk |  2 +-
 testcases/kernel/mem/lib/mem.c         | 53 +++++++++++++++++++++++++++-------
 2 files changed, 43 insertions(+), 12 deletions(-)

diff --git a/testcases/kernel/mem/include/libmem.mk 
b/testcases/kernel/mem/include/libmem.mk
index 4503e78..dffa379 100644
--- a/testcases/kernel/mem/include/libmem.mk
+++ b/testcases/kernel/mem/include/libmem.mk
@@ -23,7 +23,7 @@ MEM_DIR                       := 
$(top_builddir)/testcases/kernel/mem
 LIBMEM_DIR             := $(MEM_DIR)/lib
 LIBMEM                 := $(LIBMEM_DIR)/libmem.a
 FILTER_OUT_DIRS                := $(LIBMEM_DIR)
-CFLAGS                 += -I$(MEM_SRCDIR)/include
+CFLAGS                 += -I$(MEM_SRCDIR)/include -lpthread
 LDLIBS                 += $(NUMA_LIBS) -lmem -lltp
 LDFLAGS                        += -L$(LIBMEM_DIR)
 
diff --git a/testcases/kernel/mem/lib/mem.c b/testcases/kernel/mem/lib/mem.c
index 37cf18f..f0cd728 100644
--- a/testcases/kernel/mem/lib/mem.c
+++ b/testcases/kernel/mem/lib/mem.c
@@ -12,6 +12,7 @@
 #if HAVE_NUMAIF_H
 #include <numaif.h>
 #endif
+#include <pthread.h>
 #include <stdarg.h>
 #include <stdio.h>
 #include <string.h>
@@ -30,7 +31,8 @@ static int alloc_mem(long int length, int testcase)
        char *s;
        long i, pagesz = getpagesize();
 
-       tst_resm(TINFO, "allocating %ld bytes.", length);
+       tst_resm(TINFO, "thread (%lx), allocating %ld bytes.",
+               (unsigned long) pthread_self(), length);
 
        s = mmap(NULL, length, PROT_READ | PROT_WRITE,
                 MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
@@ -49,18 +51,46 @@ static int alloc_mem(long int length, int testcase)
        return 0;
 }
 
-static void test_alloc(int testcase, int lite)
+static void *child_alloc_thread(void *args)
 {
-       int ret;
+       int ret = 0;
+
+       /* keep allocating until there's an error */
+       while (!ret)
+               ret = alloc_mem(LENGTH, (long)args);
+       exit(ret);
+}
+
+static void child_alloc(int testcase, int lite, int threads)
+{
+       int i;
+       pthread_t *th;
 
        if (lite) {
-               ret = alloc_mem(TESTMEM + MB, testcase);
-       } else {
-               ret = 0;
-               while (!ret)
-                       ret = alloc_mem(LENGTH, testcase);
+               int ret = alloc_mem(TESTMEM + MB, testcase);
+               exit(ret);
        }
-       exit(ret);
+
+       th = malloc(sizeof(pthread_t) * threads);
+       if (!th) {
+               tst_resm(TINFO | TERRNO, "malloc");
+               goto out;
+       }
+
+       for (i = 0; i < threads; i++) {
+               TEST(pthread_create(&th[i], NULL, child_alloc_thread,
+                       (void*)((long)testcase)));
+               if (TEST_RETURN) {
+                       tst_resm(TINFO | TRERRNO, "pthread_create");
+                       goto out;
+               }
+       }
+
+       /* wait for one of threads to exit whole process */
+       while (1)
+               sleep(1);
+out:
+       exit(1);
 }
 
 /*
@@ -81,13 +111,14 @@ static void test_alloc(int testcase, int lite)
 void oom(int testcase, int lite, int retcode, int allow_sigkill)
 {
        pid_t pid;
-       int status;
+       int status, threads;
 
        switch (pid = fork()) {
        case -1:
                tst_brkm(TBROK | TERRNO, cleanup, "fork");
        case 0:
-               test_alloc(testcase, lite);
+               threads = MAX(1, tst_ncpus() - 1);
+               child_alloc(testcase, lite, threads);
        default:
                break;
        }
-- 
1.8.3.1


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