Re: PATCH reduce impact of FIFREEZE on userland processes

2012-12-09 Thread Dave Chinner
On Sat, Dec 08, 2012 at 08:47:34AM +, Alun wrote: > On Sat, 8 Dec 2012 12:20:29 +1100 > Dave Chinner wrote: > > First off, thanks for the examples. I'll answer your one question and > then I'll shut up! > > > > I'll try and chase this up by submitting patches to lvcreate and > > > fsfreeze (

Re: PATCH reduce impact of FIFREEZE on userland processes

2012-12-09 Thread Dave Chinner
On Sat, Dec 08, 2012 at 07:12:04AM -0500, Christoph Hellwig wrote: > On Fri, Dec 07, 2012 at 11:42:55AM +1100, Dave Chinner wrote: > > The problem wth doing this is that the sync can delay the freeze > > process by quite some time under the exact conditions you describe. > > If you want freeze to t

Re: PATCH reduce impact of FIFREEZE on userland processes

2012-12-08 Thread Christoph Hellwig
On Fri, Dec 07, 2012 at 11:42:55AM +1100, Dave Chinner wrote: > The problem wth doing this is that the sync can delay the freeze > process by quite some time under the exact conditions you describe. > If you want freeze to take effect immediately (i.e instantly stop > new modifications), then addin

Re: PATCH reduce impact of FIFREEZE on userland processes

2012-12-08 Thread Alun
On Sat, 8 Dec 2012 12:20:29 +1100 Dave Chinner wrote: First off, thanks for the examples. I'll answer your one question and then I'll shut up! > > I'll try and chase this up by submitting patches to lvcreate and > > fsfreeze (in the former case, I think there's no reason not to run > > syncfs; i

Re: PATCH reduce impact of FIFREEZE on userland processes

2012-12-07 Thread Dave Chinner
On Fri, Dec 07, 2012 at 08:59:52AM +, Alun wrote: > Dave Chinner said, in message > 20121207004255.GC27172@dastard: > > > > The problem wth doing this is that the sync can delay the freeze > > process by quite some time under the exact conditions you describe. > > If you want freeze to take e

Re: PATCH reduce impact of FIFREEZE on userland processes

2012-12-07 Thread Alun
Dave Chinner said, in message 20121207004255.GC27172@dastard: > > The problem wth doing this is that the sync can delay the freeze > process by quite some time under the exact conditions you describe. > If you want freeze to take effect immediately (i.e instantly stop > new modifications), then a

Re: PATCH reduce impact of FIFREEZE on userland processes

2012-12-06 Thread Dave Chinner
On Wed, Dec 05, 2012 at 09:17:07PM +, Alun wrote: > > This patch is against kernel version 3.7-rc7. > > The FIFREEZE ioctl blocks userland writes, then calls sync_filesystem. > If there is a large amount of dirty data, this sync can take a > substantial time to complete, with corresponding lo

PATCH reduce impact of FIFREEZE on userland processes

2012-12-05 Thread Alun
This patch is against kernel version 3.7-rc7. The FIFREEZE ioctl blocks userland writes, then calls sync_filesystem. If there is a large amount of dirty data, this sync can take a substantial time to complete, with corresponding loss of responsiveness to any userland processes wishing to write.