From: Nick Piggin <piggin@cyberone.com.au>
To: Randy Appleton <rappleto@nmu.edu>
Cc: Bill Davidsen <davidsen@tmr.com>, linux-kernel@vger.kernel.org
Subject: Re: Unneeded Code Found??
Date: Sat, 24 Jan 2004 11:00:06 +1100 [thread overview]
Message-ID: <4011B586.1090101@cyberone.com.au> (raw)
In-Reply-To: <40119EC6.9010803@nmu.edu>
Randy Appleton wrote:
> Nick Piggin wrote:
>
>> Yes it gets used.
>>
>> I think its a lot more common with direct io and when you have lots of
>> processes.
>
>
> I'm not arguing, but how do you know this? I'm trying to convince
> myself that the code is used, and at least on my system
> a few days of general use, followed by heavy parallel compiles,
> doesn't use the code even once.
>
> I have not tested direct I/O. Otherwise it looks unused.
>
Because I have seen it - I have instrumented it.
Your usage patterns are pretty tame actually. I remember having 100
processes
randomly reading from the same part of the disk was one of my test cases.
You need direct IO otherwise everything ends up in pagecache.
I haven't seen workloads where it gets used a lot, but that doesn't mean
they
don't exist, and I've never seen the code cause any problems, so there is no
need to make any trade offs by removing it.
next prev parent reply other threads:[~2004-01-24 0:00 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-01-09 23:28 Unneeded Code Found?? Randy Appleton
2004-01-15 16:02 ` Bill Davidsen
2004-01-19 0:58 ` Randy Appleton
2004-01-19 0:30 ` Mike Fedyk
2004-01-19 5:54 ` Nick Piggin
2004-01-23 22:23 ` Randy Appleton
2004-01-24 0:00 ` Nick Piggin [this message]
2004-01-25 22:36 ` Randy Appleton
2004-01-23 22:10 ` Jens Axboe
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