From: Wu Fengguang <fengguang.wu@intel.com>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Rik van Riel <riel@redhat.com>,
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>, 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: Fri, 19 Nov 2010 00:22:22 +0800 [thread overview]
Message-ID: <20101118162222.GA20875@localhost> (raw)
In-Reply-To: <20101118160652.GA19459@localhost>
On Fri, Nov 19, 2010 at 12:06:52AM +0800, Wu Fengguang wrote:
> On Fri, Nov 19, 2010 at 12:02:01AM +0800, Peter Zijlstra wrote:
> > On Thu, 2010-11-18 at 23:44 +0800, Wu Fengguang wrote:
> > > + pause = HZ * pages_dirtied / (bw + 1);
> >
> > Shouldn't that be using something like div64_u64 ?
>
> OK, but a dumb question: gcc cannot handle this implicitly?
Hmm, I'm tempting to do
pause = HZ * pages_dirtied / ((unsigned long)bw + 1);
because here "bw" is guaranteed to be smaller than ULONG_MAX.
Thanks,
Fengguang
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next prev parent reply other threads:[~2010-11-18 16:22 UTC|newest]
Thread overview: 13+ 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 14:27 ` Rik van Riel
2010-11-18 15:44 ` Wu Fengguang
2010-11-18 16:02 ` Peter Zijlstra
2010-11-18 16:06 ` Wu Fengguang
2010-11-18 16:22 ` Wu Fengguang [this message]
2010-11-18 16:36 ` Wu Fengguang
2010-11-18 16:29 ` Peter Zijlstra
2010-11-18 16:34 ` Wu Fengguang
2010-11-18 16:13 ` Wu Fengguang
2010-11-19 16:06 ` Michal Hocko
2010-11-19 18:44 ` Wu Fengguang
2010-11-22 9:54 ` Michal Hocko
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