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percpu: add test module for various percpu operations 

Tests various percpu operations.

Enable with CONFIG_PERCPU_TEST=m.

Signed-off-by: Greg Thelen <gthelen@google.com>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Greg Thelen 2013-11-12 15:08:34 -08:00 committed by Linus Torvalds
parent 3d035f5806
commit 623fd8072c
3 changed files with 149 additions and 0 deletions
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9
lib/Kconfig.debug
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@ -1481,6 +1481,15 @@ config INTERVAL_TREE_TEST
help
A benchmark measuring the performance of the interval tree library
config PERCPU_TEST
tristate "Per cpu operations test"
depends on m && DEBUG_KERNEL
help
Enable this option to build test module which validates per-cpu
operations.
If unsure, say N.
config ATOMIC64_SELFTEST
bool "Perform an atomic64_t self-test at boot"
help

2
lib/Makefile
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@ -157,6 +157,8 @@ obj-$(CONFIG_INTERVAL_TREE_TEST) += interval_tree_test.o
interval_tree_test-objs := interval_tree_test_main.o interval_tree.o
obj-$(CONFIG_PERCPU_TEST) += percpu_test.o
obj-$(CONFIG_ASN1) += asn1_decoder.o
obj-$(CONFIG_FONT_SUPPORT) += fonts/

138
lib/percpu_test.c Normal file
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@ -0,0 +1,138 @@
#include <linux/module.h>
/* validate @native and @pcp counter values match @expected */
#define CHECK(native, pcp, expected) \
do { \
WARN((native) != (expected), \
"raw %ld (0x%lx) != expected %lld (0x%llx)", \
(native), (native), \
(long long)(expected), (long long)(expected)); \
WARN(__this_cpu_read(pcp) != (expected), \
"pcp %ld (0x%lx) != expected %lld (0x%llx)", \
__this_cpu_read(pcp), __this_cpu_read(pcp), \
(long long)(expected), (long long)(expected)); \
} while (0)
static DEFINE_PER_CPU(long, long_counter);
static DEFINE_PER_CPU(unsigned long, ulong_counter);
static int __init percpu_test_init(void)
{
/*
* volatile prevents compiler from optimizing it uses, otherwise the
* +ul_one/-ul_one below would replace with inc/dec instructions.
*/
volatile unsigned int ui_one = 1;
long l = 0;
unsigned long ul = 0;
pr_info("percpu test start\n");
preempt_disable();
l += -1;
__this_cpu_add(long_counter, -1);
CHECK(l, long_counter, -1);
l += 1;
__this_cpu_add(long_counter, 1);
CHECK(l, long_counter, 0);
ul = 0;
__this_cpu_write(ulong_counter, 0);
ul += 1UL;
__this_cpu_add(ulong_counter, 1UL);
CHECK(ul, ulong_counter, 1);
ul += -1UL;
__this_cpu_add(ulong_counter, -1UL);
CHECK(ul, ulong_counter, 0);
ul += -(unsigned long)1;
__this_cpu_add(ulong_counter, -(unsigned long)1);
CHECK(ul, ulong_counter, -1);
ul = 0;
__this_cpu_write(ulong_counter, 0);
ul -= 1;
__this_cpu_dec(ulong_counter);
CHECK(ul, ulong_counter, -1);
CHECK(ul, ulong_counter, ULONG_MAX);
l += -ui_one;
__this_cpu_add(long_counter, -ui_one);
CHECK(l, long_counter, 0xffffffff);
l += ui_one;
__this_cpu_add(long_counter, ui_one);
CHECK(l, long_counter, (long)0x100000000LL);
l = 0;
__this_cpu_write(long_counter, 0);
l -= ui_one;
__this_cpu_sub(long_counter, ui_one);
CHECK(l, long_counter, -1);
l = 0;
__this_cpu_write(long_counter, 0);
l += ui_one;
__this_cpu_add(long_counter, ui_one);
CHECK(l, long_counter, 1);
l += -ui_one;
__this_cpu_add(long_counter, -ui_one);
CHECK(l, long_counter, (long)0x100000000LL);
l = 0;
__this_cpu_write(long_counter, 0);
l -= ui_one;
this_cpu_sub(long_counter, ui_one);
CHECK(l, long_counter, -1);
CHECK(l, long_counter, ULONG_MAX);
ul = 0;
__this_cpu_write(ulong_counter, 0);
ul += ui_one;
__this_cpu_add(ulong_counter, ui_one);
CHECK(ul, ulong_counter, 1);
ul = 0;
__this_cpu_write(ulong_counter, 0);
ul -= ui_one;
__this_cpu_sub(ulong_counter, ui_one);
CHECK(ul, ulong_counter, -1);
CHECK(ul, ulong_counter, ULONG_MAX);
ul = 3;
__this_cpu_write(ulong_counter, 3);
ul = this_cpu_sub_return(ulong_counter, ui_one);
CHECK(ul, ulong_counter, 2);
ul = __this_cpu_sub_return(ulong_counter, ui_one);
CHECK(ul, ulong_counter, 1);
preempt_enable();
pr_info("percpu test done\n");
return -EAGAIN; /* Fail will directly unload the module */
}
static void __exit percpu_test_exit(void)
{
}
module_init(percpu_test_init)
module_exit(percpu_test_exit)
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Greg Thelen");
MODULE_DESCRIPTION("percpu operations test");