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From: "Ray Lee" <ray-lk@madrabbit.org>
To: "Nick Piggin" <nickpiggin@yahoo.com.au>
Cc: "Peter Zijlstra" <peterz@infradead.org>,
	"Ingo Molnar" <mingo@elte.hu>,
	"LKML," <linux-kernel@vger.kernel.org>
Subject: Re: Poor PostgreSQL scaling on Linux 2.6.25-rc5 (vs 2.6.22)
Date: Sun, 16 Mar 2008 22:16:36 -0700	[thread overview]
Message-ID: <2c0942db0803162216r1892782bsc894d4188b51481b@mail.gmail.com> (raw)
In-Reply-To: <200803171144.35479.nickpiggin@yahoo.com.au>

On Sun, Mar 16, 2008 at 5:44 PM, Nick Piggin <nickpiggin@yahoo.com.au> wrote:
>  I don't see how it is really helpful for interactive processes either.
>  By definition, if they are not CPU bound, then they should be run
>  quite soon after waking up; if they are CPU bound, then reducing
>  efficiency by increasing context switches is effectively going to
>  increase their latency anyway.

How? Are you saying that switching the granularity to, say, 25ms, will
*decrease* the latency of interactive tasks?

And the efficiency we're talking about reducing here is due to the
fact that tasks are hitting cold caches more times per second when the
granularity is smaller, correct? Or are you concerned by another
issue?

> Can this be changed by default, please?

Not without benchmarks of interactivity, please. There are far, far
more linux desktops than there are servers. People expect to have to
tune servers (I do, for the servers I maintain). People don't expect
to have to tune a desktop to make it run well.

  reply	other threads:[~2008-03-17  5:16 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-03-11  6:49 Nick Piggin
2008-03-11  7:58 ` Ingo Molnar
2008-03-11  8:28   ` Nick Piggin
2008-03-11  9:59     ` Ingo Molnar
2008-03-11 21:07 ` Nicholas Miell
2008-03-11 21:34   ` Cyrus Massoumi
2008-03-11 23:12     ` Nicholas Miell
2008-03-11 23:42       ` Nick Piggin
2008-03-11 23:47       ` Stephen Hemminger
2008-03-12  9:00       ` Zhang, Yanmin
     [not found] ` <20080311102538.GA30551@elte.hu>
     [not found]   ` <20080311120230.GA5386@elte.hu>
2008-03-12  1:21     ` Nick Piggin
2008-03-12  7:58       ` Peter Zijlstra
2008-03-17  0:44         ` Nick Piggin
2008-03-17  5:16           ` Ray Lee [this message]
2008-03-17  5:21             ` Willy Tarreau
2008-03-17  7:19               ` Nick Piggin
2008-03-17  8:26                 ` Willy Tarreau
2008-03-17  8:54                   ` Nick Piggin
2008-03-17  9:28                     ` Peter Zijlstra
2008-03-17  9:56                       ` Nick Piggin
2008-03-17 10:16                       ` Ingo Molnar
2008-03-17  5:34             ` Nick Piggin
2008-03-14 15:42 Xose Vazquez Perez

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