From: Jeff King <peff@peff.net>
To: "SZEDER Gábor" <szeder.dev@gmail.com>
Cc: Jacob Keller <jacob.keller@gmail.com>,
Jacob Keller <jacob.e.keller@intel.com>,
Git mailing list <git@vger.kernel.org>
Subject: Re: [PATCH v3] coccicheck: process every source file at once
Date: Wed, 10 Oct 2018 09:59:52 -0400 [thread overview]
Message-ID: <20181010135952.GA2933@sigill.intra.peff.net> (raw)
In-Reply-To: <20181010114441.GD23446@szeder.dev>
On Wed, Oct 10, 2018 at 01:44:41PM +0200, SZEDER Gábor wrote:
> > So that's really weird and counter-intuitive, since we should be doing
> > strictly less work. I know that spatch tries to parallelize itself,
> > though from my tests, 1.0.4 does not. I wonder if the version in Travis
> > differs in that respect and starts too many threads, and the extra time
> > is going to contention and context switches.
>
> I don't think it does any parallel work.
>
> Here is the timing again from my previous email:
>
> 960.50user 22.59system 16:23.74elapsed 99%CPU (0avgtext+0avgdata 1606156maxresident)k
>
> Notice that 16:23 is 983s, and that it matches the sum of the user and
> system times. I usually saw this kind of timing with CPU-intensive
> single-threaded programs, and if there were any parallelization, then I
> would expect the elapsed time to be at least somewhat smaller than the
> other two.
Ah, right, I should have been able to figure that out myself. So scratch
that theory. My "hypervisor stalling our memory reads" theory is still
plausible, but I don't know how we would test it.
I guess in some sense it doesn't matter. If it's slower, we're not
likely to be able to fix that. So I guess we just need the fallback to
the current behavior.
-Peff
next prev parent reply other threads:[~2018-10-10 13:59 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-02 20:07 [PATCH v3] coccicheck: process every source file at once Jacob Keller
2018-10-02 20:18 ` Jacob Keller
2018-10-05 2:17 ` Jacob Keller
2018-10-05 12:40 ` SZEDER Gábor
2018-10-05 16:25 ` Jeff King
2018-10-05 16:53 ` Keller, Jacob E
2018-10-05 16:59 ` Jeff King
2018-10-05 18:50 ` SZEDER Gábor
2018-10-05 19:00 ` Jeff King
2018-10-05 23:10 ` Jacob Keller
2018-10-06 8:42 ` René Scharfe
2018-10-09 3:11 ` Jeff King
2018-10-05 18:39 ` SZEDER Gábor
2018-10-05 19:02 ` Jeff King
2018-10-05 19:54 ` SZEDER Gábor
2018-10-09 3:15 ` Jeff King
2018-10-10 11:44 ` SZEDER Gábor
2018-10-10 13:59 ` Jeff King [this message]
2018-10-07 11:36 ` Beat Bolli
2018-10-07 11:49 ` Beat Bolli
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