From: Dave Chinner <david@fromorbit.com>
To: Fengguang Wu <fengguang.wu@intel.com>
Cc: Wanpeng Li <liwp.linux@gmail.com>,
linux-kernel@vger.kernel.org,
Gavin Shan <shangw@linux.vnet.ibm.com>
Subject: Re: [PATCH v2] writeback: avoid race when update bandwidth
Date: Wed, 13 Jun 2012 13:59:20 +1000 [thread overview]
Message-ID: <20120613035920.GV22848@dastard> (raw)
In-Reply-To: <20120612115219.GA17348@localhost>
On Tue, Jun 12, 2012 at 07:52:19PM +0800, Fengguang Wu wrote:
> On Tue, Jun 12, 2012 at 07:46:01PM +0800, Wanpeng Li wrote:
> > From: Wanpeng Li <liwp@linux.vnet.ibm.com>
> >
> > "V1 -> V2"
> > * remove dirty_lock
> >
> > Since bdi->wb.list_lock is used to protect the b_* lists,
> > so the flushers who call wb_writeback to writeback pages will
> > stuck when bandwidth update policy holds this lock. In order
> > to avoid this race we can introduce a new bandwidth_lock who
> > is responsible for protecting bandwidth update policy.
> >
> > Signed-off-by: Wanpeng Li <liwp.linux@gmail.com>
>
> Applied with a new title "writeback: use a standalone lock for
> updating write bandwidth". "race" is sensitive because it often
> refers to some locking error.
Fengguang - can we get some evidence that this is a contended lock
before changing the scope of it? All of the previous "breaking up
global locks" have been done based on lock contention data, so
moving back to a global lock for this needs to have the same
analysis provided...
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
next prev parent reply other threads:[~2012-06-13 3:59 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-12 11:46 [PATCH v2] writeback: avoid race when update bandwidth Wanpeng Li
2012-06-12 11:52 ` Fengguang Wu
2012-06-12 11:58 ` Wanpeng Li
2012-06-13 3:59 ` Dave Chinner [this message]
2012-06-13 12:14 ` Fengguang Wu
2012-06-14 2:05 ` Dave Chinner
2012-06-14 14:00 ` Fengguang Wu
2012-06-15 0:06 ` Dave Chinner
2012-06-15 0:29 ` Fengguang Wu
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