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Message-Id: <20081117132631.A88A0DDE0A@ozlabs.org>
Date: Mon Nov 17 23:48:27 CST 2008
From: Rusty Russell <rusty@...tcorp.com.au>
To: linux-kernel@...r.kernel.org
Cc: Christoph Lameter <cl@...ux-foundation.org>
Subject: [PATCH 7/7] Improve alloc_percpu: Simple testing patch.
Note that we can use the ptr ops on static percpu vars now. We should
remove the "per_cpu__" token-pasting which was designed to catch raw
usage, and use sparse annotations instead.
Signed-off-by: Rusty Russell <rusty@...tcorp.com.au>
Cc: Christoph Lameter <cl@...ux-foundation.org>
---
include/linux/percpu.h | 2 +
init/Kconfig | 6 ++++
init/Makefile | 1
init/main.c | 1
init/test-cpualloc.c | 61 +++++++++++++++++++++++++++++++++++++++++++++++++
mm/allocpercpu.c | 7 ++---
6 files changed, 74 insertions(+), 4 deletions(-)
diff -r 3b3fa686230f init/Kconfig
--- a/init/Kconfig Mon Nov 17 23:19:14 2008 +1030
+++ b/init/Kconfig Mon Nov 17 23:39:58 2008 +1030
@@ -929,3 +929,9 @@
designed for best read-side performance on non-realtime
systems. Classic RCU is the default. Note that the
PREEMPT_RCU symbol is used to select/deselect this option.
+
+config TEST_CPUALLOC
+ tristate "Test alloc_percpu"
+ depends on DEBUG_KERNEL
+ help
+ This tests the replacement alloc_percpu() implementation.
diff -r 3b3fa686230f init/Makefile
--- a/init/Makefile Mon Nov 17 23:19:14 2008 +1030
+++ b/init/Makefile Mon Nov 17 23:39:58 2008 +1030
@@ -9,6 +9,7 @@
obj-$(CONFIG_BLK_DEV_INITRD) += initramfs.o
endif
obj-$(CONFIG_GENERIC_CALIBRATE_DELAY) += calibrate.o
+obj-$(CONFIG_TEST_CPUALLOC) += test-cpualloc.o
mounts-y := do_mounts.o
mounts-$(CONFIG_BLK_DEV_RAM) += do_mounts_rd.o
diff -r 3b3fa686230f init/test-cpualloc.c
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/init/test-cpualloc.c Mon Nov 17 23:39:58 2008 +1030
@@ -0,0 +1,75 @@
+/* Not a very informative test: it just crashes if something's wrong. */
+#include <linux/percpu.h>
+#include <linux/module.h>
+
+static DEFINE_PER_CPU(u64, static_pcpu);
+
+static int init(void)
+{
+ void *p, *thisp;
+ u64 *p64, *thisp64;
+ unsigned int i;
+
+ printk(KERN_INFO "Testing cpualloc for %u cpus\n",
+ cpus_weight(cpu_possible_map));
+
+ p = __alloc_percpu(100, 128);
+ /* Don't expect failure. */
+ BUG_ON(!p);
+
+ thisp = get_cpu_ptr(p);
+ for_each_possible_cpu(i) {
+ unsigned int j;
+ /* Must be aligned. */
+ BUG_ON((unsigned long)per_cpu_ptr(p, i) % 128);
+ /* Must be zeroed. */
+ for (j = 0; j < 100; j++)
+ BUG_ON(((char *)per_cpu_ptr(p, i))[j]);
+ if (i == smp_processor_id())
+ BUG_ON(per_cpu_ptr(p, i) != thisp);
+ /* Check they're different pointers. */
+ memset(per_cpu_ptr(p, i), 0xFF, 100);
+ }
+ free_percpu(p);
+ put_cpu_ptr(p);
+
+ p64 = alloc_percpu(u64);
+ /* Don't expect failure. */
+ BUG_ON(!p64);
+
+ thisp64 = get_cpu_ptr(p64);
+ for_each_possible_cpu(i) {
+ /* Must be aligned. */
+ BUG_ON((unsigned long)per_cpu_ptr(p64, i) % __alignof__(u64));
+ /* Must be zeroed. */
+ BUG_ON(*per_cpu_ptr(p64, i));
+ if (i == smp_processor_id())
+ BUG_ON(per_cpu_ptr(p64, i) != thisp64);
+ /* Check they're different pointers. */
+ *per_cpu_ptr(p64, i) = -1ULL;
+ }
+ free_percpu(p64);
+ put_cpu_ptr(p64);
+
+ /* It even works on static percpu vars (though currently awkward) */
+ p64 = &per_cpu__static_pcpu;
+ thisp64 = get_cpu_ptr(p64);
+ for_each_possible_cpu(i) {
+ /* Must be aligned. */
+ BUG_ON((unsigned long)per_cpu_ptr(p64, i) % __alignof__(u64));
+ /* Must be zeroed. */
+ BUG_ON(*per_cpu_ptr(p64, i));
+ if (i == smp_processor_id())
+ BUG_ON(per_cpu_ptr(p64, i) != thisp64);
+ /* Check they're different pointers. */
+ *per_cpu_ptr(p64, i) = -1ULL;
+ }
+ put_cpu_ptr(p64);
+ return 0;
+}
+
+static void fini(void)
+{
+}
+module_init(init);
+module_exit(fini);
--
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