From: Joe Perches <joe@perches.com>
To: Yuyang Du <yuyang.du@intel.com>,
peterz@infradead.org, mingo@kernel.org,
linux-kernel@vger.kernel.org
Cc: bsegall@google.com, pjt@google.com, morten.rasmussen@arm.com,
vincent.guittot@linaro.org, dietmar.eggemann@arm.com
Subject: Re: [PATCH] sched/fair: Optimize sum computation with a lookup table
Date: Fri, 08 Apr 2016 03:31:41 -0700 [thread overview]
Message-ID: <1460111501.1800.28.camel@perches.com> (raw)
In-Reply-To: <1460081240-8074-1-git-send-email-yuyang.du@intel.com>
On Fri, 2016-04-08 at 10:07 +0800, Yuyang Du wrote:
> __compute_runnable_contrib() uses a loop to compute sum, whereas a
> table lookup can do it faster in a constant time.
Perhaps this becomes rather fragile code overly dependent on the
current #define values of LOAD_AVG_MAX_N and LOAD_AVG_PERIOD.
Perhaps this comment just above the definitions of LOAD_AVG_MAX_N
and LOAD_AVG_PERIOD should be updated to include this new table:
* Note: The tables runnable_avg_yN_inv and runnable_avg_yN_sum are
* dependent on this value.
Perhaps the __ prefix for __accumulated_sum_N32 is odd as both of
the runnable_avg_yN_ tables are not __ prefixed.
next prev parent reply other threads:[~2016-04-08 10:31 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-08 2:07 [PATCH] sched/fair: Optimize sum computation with a lookup table Yuyang Du
2016-04-08 10:31 ` Joe Perches [this message]
2016-04-08 10:54 ` Peter Zijlstra
2016-04-08 16:22 ` Juri Lelli
2016-04-08 10:44 ` Peter Zijlstra
2016-04-08 10:45 ` Peter Zijlstra
2016-04-08 11:30 ` Morten Rasmussen
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