From: Andrew Morton <akpm@linux-foundation.org>
To: Wu Fengguang <fengguang.wu@intel.com>
Cc: Jens Axboe <jens.axboe@oracle.com>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Ehrhardt Christian <ehrhardt@linux.vnet.ibm.com>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Martin Schwidefsky <schwidefsky@de.ibm.com>
Subject: Re: [PATCH] mm: make VM_MAX_READAHEAD configurable
Date: Sat, 10 Oct 2009 10:41:11 -0700 [thread overview]
Message-ID: <20091010104111.547d8abe.akpm@linux-foundation.org> (raw)
In-Reply-To: <20091010124042.GA9179@localhost>
On Sat, 10 Oct 2009 20:40:42 +0800 Wu Fengguang <fengguang.wu@intel.com> wrote:
> > not sure if it attempts to do anything based on how quickly
> > the device is doing IO. Wu?
>
> Not for current kernel. But in fact it's possible to estimate the
> read speed for each individual sequential stream, and possibly drop
> some hint to the IO scheduler: someone will block on this IO after 3
> seconds. But it may not deserve the complexity.
Well, we have a test case. Would any of your design proposals address
the performance problem which motivated the s390 guys to propose this
patch?
WARNING: multiple messages have this Message-ID (diff)
From: Andrew Morton <akpm@linux-foundation.org>
To: Wu Fengguang <fengguang.wu@intel.com>
Cc: Jens Axboe <jens.axboe@oracle.com>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Ehrhardt Christian <ehrhardt@linux.vnet.ibm.com>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Martin Schwidefsky <schwidefsky@de.ibm.com>
Subject: Re: [PATCH] mm: make VM_MAX_READAHEAD configurable
Date: Sat, 10 Oct 2009 10:41:11 -0700 [thread overview]
Message-ID: <20091010104111.547d8abe.akpm@linux-foundation.org> (raw)
In-Reply-To: <20091010124042.GA9179@localhost>
On Sat, 10 Oct 2009 20:40:42 +0800 Wu Fengguang <fengguang.wu@intel.com> wrote:
> > not sure if it attempts to do anything based on how quickly
> > the device is doing IO. Wu?
>
> Not for current kernel. But in fact it's possible to estimate the
> read speed for each individual sequential stream, and possibly drop
> some hint to the IO scheduler: someone will block on this IO after 3
> seconds. But it may not deserve the complexity.
Well, we have a test case. Would any of your design proposals address
the performance problem which motivated the s390 guys to propose this
patch?
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next prev parent reply other threads:[~2009-10-10 17:42 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-10-09 11:19 [PATCH] mm: make VM_MAX_READAHEAD configurable Ehrhardt Christian
2009-10-09 11:19 ` Ehrhardt Christian
2009-10-09 12:20 ` Peter Zijlstra
2009-10-09 12:20 ` Peter Zijlstra
2009-10-09 12:29 ` Jens Axboe
2009-10-09 12:29 ` Jens Axboe
2009-10-09 13:49 ` Martin Schwidefsky
2009-10-09 13:49 ` Martin Schwidefsky
2009-10-09 13:58 ` Wu Fengguang
2009-10-09 13:58 ` Wu Fengguang
2009-10-11 1:10 ` Wu Fengguang
2009-10-11 1:10 ` Wu Fengguang
2009-10-12 5:53 ` Christian Ehrhardt
2009-10-12 5:53 ` Christian Ehrhardt
2009-10-12 6:23 ` Wu Fengguang
2009-10-12 6:23 ` Wu Fengguang
2009-10-12 9:29 ` Christian Ehrhardt
2009-10-12 9:29 ` Christian Ehrhardt
2009-10-12 9:39 ` Wu Fengguang
2009-10-12 9:39 ` Wu Fengguang
2009-10-09 21:31 ` Andrew Morton
2009-10-09 21:31 ` Andrew Morton
2009-10-10 10:53 ` Jens Axboe
2009-10-10 10:53 ` Jens Axboe
2009-10-10 12:40 ` Wu Fengguang
2009-10-10 12:40 ` Wu Fengguang
2009-10-10 17:41 ` Andrew Morton [this message]
2009-10-10 17:41 ` Andrew Morton
2009-10-09 13:14 ` Wu Fengguang
2009-10-09 13:14 ` Wu Fengguang
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