linux-kernel - Re: [GIT PULL] cputime: Full dynticks task/cputime accounting v7

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Message-ID: <1359417749.17639.6.camel@gandalf.local.home>
Date:	Mon, 28 Jan 2013 19:02:29 -0500
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Frederic Weisbecker <fweisbec@...il.com>
Cc:	Ingo Molnar <mingo@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Li Zhong <zhong@...ux.vnet.ibm.com>,
	Namhyung Kim <namhyung.kim@....com>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Paul Gortmaker <paul.gortmaker@...driver.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Sedat Dilek <sedat.dilek@...il.com>,
	Gleb Natapov <gleb@...hat.com>,
	Marcelo Tosatti <mtosatti@...hat.com>,
	Tony Luck <tony.luck@...el.com>,
	Fenghua Yu <fenghua.yu@...el.com>
Subject: Re: [GIT PULL] cputime: Full dynticks task/cputime accounting v7

On Mon, 2013-01-28 at 20:03 +0100, Frederic Weisbecker wrote:
> Ingo,
> 
> Please pull the new full dynticks cputime accounting code that
> can be found at:
> 
> git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks.git
> 	tags/full-dynticks-cputime-for-mingo
> 
> My last concern is the dependency on CONFIG_64BIT. We rely on cputime_t
> being u64 for reasonable nanosec granularity implementation. And therefore
> we need a single instruction fetch to read kernel cpustat for atomicity
> requirement against concurrent incrementation, which only 64 bit archs
> can provide.
> 
> It's probably no big deal to solve this issue. What we need is simply some
> atomic accessors.
> 
> There is just no emergency though as this new option depends on the context
> tracking subsystem that only x86-64 (and soon ppc64) implements yet. And
> this set is complex enough already. I think we can deal with that later.

I've ran these through some basic tests and I don't see any issues. But
why did you drop the 'comment' patch that you had in v6?

Acked-by: Steven Rostedt <rostedt@...dmis.org>

-- Steve


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