On Wed, 2007-06-20 at 11:14 +0200, Jens Axboe wrote: > On Wed, Jun 20 2007, Andrew Morton wrote: > > Perhaps our queues are too long - if the VFS _does_ back off, it'll take > > some time for that to have an effect. > > > > Perhaps the fact that the queue size knows nothing about the _size_ of the > > requests in the queue is a problem. > > It's complicated, the size may not matter a lot. 128 sequential 512kb IO > may complete faster than 128 random 4kb IO's.
Yes, is there any way a queue could be limited to a certain amount of 'completion time' ? > > Back away even further here. > > > > What user-visible problem(s) are we attemping to fix? > > I'd like innocent-app-doing-little-write-or-fsync not being stalled by > big-bad-app-doing-lots-of-dirtying. Could you please try this per BDI dirty limit -v7 patch series, the very last patch tries to address this by taking the per task dirty rate into account. Although, on the fsync, ext3 seems to want to do a global fsync, which will still make the experience suck. :-( - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
