linux-kernel - Re: [RFC] lib/vsprintf.c: Even faster decimal conversion

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Message-ID: <87egp384m0.fsf@rasmusvillemoes.dk>
Date:	Thu, 05 Mar 2015 23:24:39 +0100
From:	Rasmus Villemoes <linux@...musvillemoes.dk>
To:	Tejun Heo <tj@...nel.org>
Cc:	Joe Perches <joe@...ches.com>, linux-kernel@...r.kernel.org,
	"Peter Zijlstra \(Intel\)" <peterz@...radead.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [RFC] lib/vsprintf.c: Even faster decimal conversion

On Thu, Mar 05 2015, Tejun Heo <tj@...nel.org> wrote:

> On Thu, Mar 05, 2015 at 08:03:33AM -0800, Joe Perches wrote:
>> On Thu, 2015-03-05 at 16:22 +0100, Rasmus Villemoes wrote:
>>
>> > I'm assuming the underwhelming response means NAK.
>> 
>> Dunno why you assume that, sometimes it just takes
>> awhile for people to look at non-critical, infrequent
>> optimization changes like this.

Well, when nobody has responded within a week with even a "not obviously
insane, I'll look at it after -rcN/next full moon/...", there's usually
little hope of ever getting some feedback.

>> Seems sensible enough to me though.
>
> I'd like to see how this actually affects larger operations - sth
> along the line of top consumes D% less CPU cycles w/ N processes - if
> for nothing else, just to get the sense of scale,

That makes sense. I'll see if I can get some reproducible numbers, but
I'm afraid the effect drowns in all the syscall overhead. Which would be
a valid argument against touching the code.

> I haven't studied the code but looks sensible enough on a glance, so,
> FWIW,
>
>  Looks-sensible-by: Tejun Heo <tj@...nel.org>

Thanks, this was the kind of feedback I was hoping for.

Rasmus
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