lkml.org 
[lkml]   [2012]   [Jun]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [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@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


\
 
 \ /
  Last update: 2012-06-13 06:41    [W:0.933 / U:0.000 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site