From: Rik van Riel <riel@redhat.com>
To: Wu Fengguang <fengguang.wu@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Jan Kara <jack@suse.cz>, "Li, Shaohua" <shaohua.li@intel.com>,
Christoph Hellwig <hch@lst.de>,
Dave Chinner <david@fromorbit.com>,
"Theodore Ts'o" <tytso@mit.edu>,
Chris Mason <chris.mason@oracle.com>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Mel Gorman <mel@csn.ul.ie>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
linux-mm <linux-mm@kvack.org>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] writeback: prevent bandwidth calculation overflow
Date: Thu, 18 Nov 2010 09:27:10 -0500 [thread overview]
Message-ID: <4CE537BE.6090103@redhat.com> (raw)
In-Reply-To: <20101118065725.GB8458@localhost>
On 11/18/2010 01:57 AM, Wu Fengguang wrote:
> On 32bit kernel, bdi->write_bandwidth can express at most 4GB/s.
>
> However the current calculation code can overflow when disk bandwidth
> reaches 800MB/s. Fix it by using "long long" and swapping the order of
> multiplication/division. And further, change its unit to pages/second
> rather than bytes/second. That allows up to 16TB/s bandwidth in 32bit
> kernel.
>
> Signed-off-by: Wu Fengguang<fengguang.wu@intel.com>
Acked-by: Rik van Riel <riel@redhat.com>
--
All rights reversed
WARNING: multiple messages have this Message-ID (diff)
From: Rik van Riel <riel@redhat.com>
To: Wu Fengguang <fengguang.wu@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Jan Kara <jack@suse.cz>, "Li, Shaohua" <shaohua.li@intel.com>,
Christoph Hellwig <hch@lst.de>,
Dave Chinner <david@fromorbit.com>,
"Theodore Ts'o" <tytso@mit.edu>,
Chris Mason <chris.mason@oracle.com>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Mel Gorman <mel@csn.ul.ie>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
linux-mm <linux-mm@kvack.org>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] writeback: prevent bandwidth calculation overflow
Date: Thu, 18 Nov 2010 09:27:10 -0500 [thread overview]
Message-ID: <4CE537BE.6090103@redhat.com> (raw)
In-Reply-To: <20101118065725.GB8458@localhost>
On 11/18/2010 01:57 AM, Wu Fengguang wrote:
> On 32bit kernel, bdi->write_bandwidth can express at most 4GB/s.
>
> However the current calculation code can overflow when disk bandwidth
> reaches 800MB/s. Fix it by using "long long" and swapping the order of
> multiplication/division. And further, change its unit to pages/second
> rather than bytes/second. That allows up to 16TB/s bandwidth in 32bit
> kernel.
>
> Signed-off-by: Wu Fengguang<fengguang.wu@intel.com>
Acked-by: Rik van Riel <riel@redhat.com>
--
All rights reversed
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next prev parent reply other threads:[~2010-11-18 14:28 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-11-18 6:57 [PATCH] writeback: prevent bandwidth calculation overflow Wu Fengguang
2010-11-18 6:57 ` Wu Fengguang
2010-11-18 14:27 ` Rik van Riel [this message]
2010-11-18 14:27 ` Rik van Riel
2010-11-18 15:44 ` Wu Fengguang
2010-11-18 15:44 ` Wu Fengguang
2010-11-18 16:02 ` Peter Zijlstra
2010-11-18 16:02 ` Peter Zijlstra
2010-11-18 16:06 ` Wu Fengguang
2010-11-18 16:06 ` Wu Fengguang
2010-11-18 16:22 ` Wu Fengguang
2010-11-18 16:22 ` Wu Fengguang
2010-11-18 16:36 ` Wu Fengguang
2010-11-18 16:36 ` Wu Fengguang
2010-11-18 16:29 ` Peter Zijlstra
2010-11-18 16:29 ` Peter Zijlstra
2010-11-18 16:34 ` Wu Fengguang
2010-11-18 16:34 ` Wu Fengguang
2010-11-18 16:13 ` Wu Fengguang
2010-11-18 16:13 ` Wu Fengguang
2010-11-19 16:06 ` Michal Hocko
2010-11-19 16:06 ` Michal Hocko
2010-11-19 18:44 ` Wu Fengguang
2010-11-19 18:44 ` Wu Fengguang
2010-11-22 9:54 ` Michal Hocko
2010-11-22 9:54 ` Michal Hocko
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