From: Dave Chinner <david@fromorbit.com>
To: Andi Kleen <andi@firstfloor.org>
Cc: Don Mullis <don.mullis@gmail.com>,
linux-kernel@vger.kernel.org, airlied@redhat.com,
dedekind@infradead.org
Subject: Re: [PATCH 1/2] lib: more scalable list_sort()
Date: Sun, 24 Jan 2010 03:05:37 +1100 [thread overview]
Message-ID: <20100123160537.GG25842@discord.disaster> (raw)
In-Reply-To: <20100123113551.GB29555@one.firstfloor.org>
On Sat, Jan 23, 2010 at 12:35:51PM +0100, Andi Kleen wrote:
> > Burning CPU time to save on IO is a very valid tradeoff in
> > filesystem design - burning a few hundred millieseconds of CPU
> > time can result in savcwinge tens of seconds of IO time. Hence
> > passing big long lists to be sorted is not an indication of broken
> > design, it's an indication of understanding CPU time vs IO time
> > tradeoffs during design...
>
> Burning long CPU time in kernel code without latency breaker code is always
> a sign of broken design.
It's a characteristic of a sub-optimal implementation, not bad
design. Plenty of code has been fixed over the years simply by
adding cond_resched() to loops that have triggered latency
warnings.
Similarly, adding cond_resched() to list_sort means you can stop
worrying about the scheduling latency impact of sorting long lists.
I fail to see why you're making such a big deal out of this.....
Cheers
Dave.
--
Dave Chinner
david@fromorbit.com
next prev parent reply other threads:[~2010-01-23 16:06 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-21 4:51 [PATCH 1/2] lib: more scalable list_sort() Don Mullis
2010-01-21 5:17 ` [PATCH 2/2] lib: revise list_sort() comment Don Mullis
2010-01-21 19:11 ` Olaf Titz
2010-01-22 4:54 ` Don Mullis
2010-01-21 9:22 ` [PATCH 1/2] lib: more scalable list_sort() Artem Bityutskiy
2010-01-21 9:54 ` Dave Chinner
2010-01-21 11:44 ` Artem Bityutskiy
2010-01-21 16:34 ` Don Mullis
2010-01-21 17:59 ` Andi Kleen
2010-01-22 3:17 ` Don Mullis
2010-01-22 10:43 ` Andi Kleen
2010-01-22 12:29 ` Artem Bityutskiy
2010-01-22 17:55 ` Don Mullis
2010-01-23 8:28 ` Dave Chinner
2010-01-23 11:35 ` Andi Kleen
2010-01-23 16:05 ` Dave Chinner [this message]
2010-01-24 20:59 ` Andi Kleen
2010-01-24 21:10 ` Artem Bityutskiy
2010-01-24 22:38 ` Don Mullis
2010-01-25 3:41 ` Dave Chinner
2010-08-04 14:04 ` Artem Bityutskiy
2010-08-07 7:50 ` Artem Bityutskiy
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