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Date: Wed, 13 Jun 2012 13:59:20 +1000 From: Dave Chinner <david@...morbit.com> To: Fengguang Wu <fengguang.wu@...el.com> Cc: Wanpeng Li <liwp.linux@...il.com>, linux-kernel@...r.kernel.org, Gavin Shan <shangw@...ux.vnet.ibm.com> Subject: Re: [PATCH v2] writeback: avoid race when update bandwidth 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@...ux.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@...il.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@...morbit.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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