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Message-Id: <1332019895-59698-1-git-send-email-nbd@openwrt.org> Date: Sat, 17 Mar 2012 22:31:35 +0100 From: Felix Fietkau <nbd@...nwrt.org> To: linux-kernel@...r.kernel.org Cc: tglx@...utronix.de Subject: [PATCH] timer: optimize apply_slack() __fls(mask) is equivalent to find_last_bit(&mask, BITS_PER_LONG), but cheaper. find_last_bit was showing up high on the list when I was profiling for stalls on icache misses on a system with very small cache size (MIPS). Signed-off-by: Felix Fietkau <nbd@...nwrt.org> --- kernel/timer.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/kernel/timer.c b/kernel/timer.c index a297ffc..659371e 100644 --- a/kernel/timer.c +++ b/kernel/timer.c @@ -809,7 +809,7 @@ unsigned long apply_slack(struct timer_list *timer, unsigned long expires) if (mask == 0) return expires; - bit = find_last_bit(&mask, BITS_PER_LONG); + bit = __fls(mask); mask = (1 << bit) - 1; -- 1.7.3.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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