From: Andrew Morton <akpm@osdl.org>
To: Badari Pulavarty <pbadari@us.ibm.com>
Cc: suparna@in.ibm.com, linux-kernel@vger.kernel.org, linux-aio@kvack.org
Subject: Re: [PATCH][2.6-mm] Readahead issues and AIO read speedup
Date: Thu, 7 Aug 2003 10:39:30 -0700 [thread overview]
Message-ID: <20030807103930.69e497a7.akpm@osdl.org> (raw)
In-Reply-To: <200308071021.39816.pbadari@us.ibm.com>
Badari Pulavarty <pbadari@us.ibm.com> wrote:
>
> We should do readahead of actual pages required by the current
> read would be correct solution. (like Suparna suggested).
I repeat: what will be the effect of this if all those pages are already in
pagecache?
> When readahead window is closed, slow read code will be submitting IO in 4k
> chunks. Infact, it will wait for the IO to finish, before reading next page.
> Isn't it?
Yes.
> How would you ensure atleast 16k worth of pages are submitted
> in a sinle chunk here ?
Need to work out why the window got itself shrunk, fix that, then constrain each
readahead chunk to the size of the application's read() if the application
just seeked, I think.
> I am hoping that forcing readhead code to read pages needed by current read
> would address this problem.
You'll have Martin and Anton coming after you with SDET regressions.
next prev parent reply other threads:[~2003-08-07 17:37 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-08-07 10:01 Suparna Bhattacharya
2003-08-07 16:01 ` Badari Pulavarty
2003-08-07 16:28 ` Andrew Morton
2003-08-07 17:21 ` Badari Pulavarty
2003-08-07 17:39 ` Andrew Morton [this message]
2003-08-07 20:41 ` Badari Pulavarty
2003-08-07 20:58 ` Andrew Morton
2003-08-08 13:56 ` Suparna Bhattacharya
2003-08-13 21:06 ` Ram Pai
2003-09-23 0:41 ` Ram Pai
2003-08-07 19:36 ` Joel Becker
2003-08-08 5:42 ` Jens Axboe
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