Messages in this thread Patch in this message | | | Date | Wed, 8 Dec 2010 20:41:52 GMT | From | tip-bot for Eric Dumazet <> | Subject | [tip:sched/core] printk: Use this_cpu_{read|write} api on printk_pending |
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Commit-ID: 40dc11ffb35e8c4e8fa71092048e0f8de9db758c Gitweb: http://git.kernel.org/tip/40dc11ffb35e8c4e8fa71092048e0f8de9db758c Author: Eric Dumazet <eric.dumazet@gmail.com> AuthorDate: Fri, 26 Nov 2010 17:22:16 +0100 Committer: Ingo Molnar <mingo@elte.hu> CommitDate: Wed, 8 Dec 2010 20:16:01 +0100
printk: Use this_cpu_{read|write} api on printk_pending
__get_cpu_var() is a bit inefficient, lets use __this_cpu_read() and __this_cpu_write() to manipulate printk_pending.
printk_needs_cpu(cpu) is called only for the current cpu : Use faster __this_cpu_read().
Remove the redundant unlikely on (cpu_is_offline(cpu)) test:
# size kernel/printk.o* text data bss dec hex filename 9942 756 263488 274186 42f0a kernel/printk.o.new 9990 756 263488 274234 42f3a kernel/printk.o.old
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Christoph Lameter <cl@linux.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1290788536.2855.237.camel@edumazet-laptop> Signed-off-by: Ingo Molnar <mingo@elte.hu> --- kernel/printk.c | 8 ++++---- 1 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/kernel/printk.c b/kernel/printk.c index a23315d..ab3ffc5 100644 --- a/kernel/printk.c +++ b/kernel/printk.c @@ -1074,17 +1074,17 @@ static DEFINE_PER_CPU(int, printk_pending); void printk_tick(void) { - if (__get_cpu_var(printk_pending)) { - __get_cpu_var(printk_pending) = 0; + if (__this_cpu_read(printk_pending)) { + __this_cpu_write(printk_pending, 0); wake_up_interruptible(&log_wait); } } int printk_needs_cpu(int cpu) { - if (unlikely(cpu_is_offline(cpu))) + if (cpu_is_offline(cpu)) printk_tick(); - return per_cpu(printk_pending, cpu); + return __this_cpu_read(printk_pending); } void wake_up_klogd(void)
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