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From: Ingo Molnar <mingo@kernel.org>
To: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Frederic Weisbecker <fweisbec@gmail.com>,
	hpa@zytor.com, rostedt@goodmis.org, akpm@linux-foundation.org,
	tglx@linutronix.de,
	Linus Torvalds <torvalds@linux-foundation.org>,
	linux-kernel@vger.kernel.org, Dave Hansen <dave@sr71.net>
Subject: Re: [PATCH -tip 1/4] sched: Avoid cputime scaling overflow
Date: Tue, 30 Apr 2013 13:11:19 +0200	[thread overview]
Message-ID: <20130430111119.GA28821@gmail.com> (raw)
In-Reply-To: <1367314507-9728-1-git-send-email-sgruszka@redhat.com>


* Stanislaw Gruszka <sgruszka@redhat.com> wrote:

> Here is patch, which add Linus cputime scaling algorithm to the kernel.
> 
> This is follow up of commit d9a3c9823a2e6a543eb7807fb3d15d8233817ec5
> "sched: Lower chances of cputime scaling overflow" which try to avoid
> multiplication overflow, but not guarantee that the overflow will not
> happen.
> 
> Linus crated different algorithm, which avoid completely multiplication
> overflow by dropping precision when numbers are big. It was tested
> by me and it gives good relative error of scaled numbers.
> 
> Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>

For multi-authored code it's generally nice to add a tag like this:

   Originally-From: Linus Torvalds <torvalds@linux-foundation.org>

It would also be nice to quote the testing results/output and the 
precision estimations in the changelog - so that others can see the code's 
current capabilities and limitations.

Thanks,

	Ingo

  parent reply	other threads:[~2013-04-30 11:11 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-04-30  9:35 [PATCH -tip 1/4] sched: Avoid cputime scaling overflow Stanislaw Gruszka
2013-04-30  9:35 ` [PATCH -tip 2/4] sched: Do not account bogus utime Stanislaw Gruszka
2013-05-01 10:04   ` [tip:sched/urgent] " tip-bot for Stanislaw Gruszka
2013-04-30  9:35 ` [PATCH -tip 3/4] sched: Avoid prev->stime underflow Stanislaw Gruszka
2013-05-01 10:06   ` [tip:sched/urgent] " tip-bot for Stanislaw Gruszka
2013-04-30  9:35 ` [PATCH -tip 4/4] Revert "math64: New div64_u64_rem helper" Stanislaw Gruszka
2013-05-01 10:07   ` [tip:sched/urgent] " tip-bot for Stanislaw Gruszka
2013-04-30 11:11 ` Ingo Molnar [this message]
2013-04-30 15:14 ` [PATCH -tip 1/4 v2] sched: Avoid cputime scaling overflow Stanislaw Gruszka
2013-05-01 10:03   ` [tip:sched/urgent] " tip-bot for Stanislaw Gruszka
2013-05-02 13:10     ` Peter Zijlstra

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