Hi Darrick, On Wed, Dec 12, 2012 at 11:47:10AM -0800, Darrick J. Wong wrote: > On Wed, Dec 12, 2012 at 01:13:32PM +0800, Zheng Liu wrote: > > On Wed, Dec 12, 2012 at 03:49:49PM +1100, Dave Chinner wrote: > > [cut...] > > > > > > Hence, I wonder whether or not we could revert stable page write temporarily. > > > > > > After it is improved, we could add it back again. > > > > > > > > > > The plan is to turn it off for filesystems/devices that don't > > > > > require it. That list of devices will grow in future, so you > > > > > probably should plan to handle latencies in the application > > > > > properly... > > > > > > > > I wonder whether we can provide a sysctl to turn on/off stable page > > > > write. At least we need to give sysadmin an opportunity to control it. > > > > > > That's already been considered and discarded because turning off > > > stable pages on devices that require it will cause validation or > > > data corruption problems. The discussion was for these patches (and > > > I think a followup series as well): > > > > > > http://www.spinics.net/lists/linux-fsdevel/msg59421.html > > > > Thanks for pointing out. So now it seems that only I can do is to > > present a proposal to revert stable page write temporarily because it > > causes a huge latency for some applications. > > Hrm... just to be clear, is your complaint that you have one of these > checksum-happy disks and overwrites are slow on it, or that you have a regular > SATA disk that doesn't require stable pages and you don't want to take the > speed hit? > > If it's the second, then let's just push the bdi flag thing upstream. Given > your comments a couple of days ago, I'm pretty sure it's the second, but I > figured I ought to clarify the record. :) Yes, it's the second. In our product system we have a large number of SATA disks that don't require stable pages. So that would be great if we have a method to turn on/off stable page. > > I haven't posted new patches because I've been busy writing a fix for ext3. > It seems to be working, so I'll clean it up and send out a new series. Cool! We are looking forward the new patch series. :-) Regards, - Zheng -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
