From: Peter Zijlstra <peterz@infradead.org>
To: qiwuchen55@gmail.com
Cc: mingo@redhat.com, juri.lelli@redhat.com,
vincent.guittot@linaro.org, dietmar.eggemann@arm.com,
rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de,
linux-kernel@vger.kernel.org, chenqiwu <chenqiwu@xiaomi.com>
Subject: Re: [PATCH] sched/pelt: use shift operation instead of division operation
Date: Mon, 24 Feb 2020 10:32:15 +0100 [thread overview]
Message-ID: <20200224093215.GC14897@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <1582515055-14515-1-git-send-email-qiwuchen55@gmail.com>
On Mon, Feb 24, 2020 at 11:30:55AM +0800, qiwuchen55@gmail.com wrote:
> From: chenqiwu <chenqiwu@xiaomi.com>
>
> Use shift operation to calculate the periods instead of division,
> since shift operation is more efficient than division operation.
>
> Signed-off-by: chenqiwu <chenqiwu@xiaomi.com>
> ---
> kernel/sched/pelt.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/sched/pelt.c b/kernel/sched/pelt.c
> index bd006b7..ac79f8e 100644
> --- a/kernel/sched/pelt.c
> +++ b/kernel/sched/pelt.c
> @@ -114,7 +114,7 @@ static u32 __accumulate_pelt_segments(u64 periods, u32 d1, u32 d3)
> u64 periods;
>
> delta += sa->period_contrib;
> - periods = delta / 1024; /* A period is 1024us (~1ms) */
> + periods = delta >> 10; /* A period is 1024us (~1ms) */
Find me a compiler that stupid.
prev parent reply other threads:[~2020-02-24 9:32 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-24 3:30 qiwuchen55
2020-02-24 9:32 ` Peter Zijlstra [this message]
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