Messages in this thread | | | Date | Sat, 4 Apr 2009 16:33:49 -0700 | From | Arjan van de Ven <> | Subject | Re: [GIT PULL] Ext3 latency fixes |
| |
On Sat, 4 Apr 2009 19:22:22 -0400 Theodore Tso <tytso@mit.edu> wrote: > > However, the full latency fixes all the writes are synchronous, so it > must be the case that the delays are caused by the fact that queue is > getting implicitly unplugged after the synchronous write, and the > problem is no longer the mixing of WRITE and WRITE_SYNC requests as > posted in the commit log for 78f707bf. If we remove the automatic > unplug for WRITE_SYNC requests, and add an explicit unplug where it is > needed, that should fix the performance regression for this particular > sqlite test case.
removing the unplug is bound to be bad; after all we're waiting on the IO. But maybe it should be "make the unplug a REALLY short time". At least for rotating storage. For non-rotating .. I'd never wait.
-- Arjan van de Ven Intel Open Source Technology Centre For development, discussion and tips for power savings, visit http://www.lesswatts.org
| |