Hello, Darrick. On Mon, Jan 24, 2011 at 12:31:55PM -0800, Darrick J. Wong wrote: > > So, I think it's better to start with something simple and improve it > > with actual testing. If the current simple implementation can match > > Darrick's previous numbers, let's first settle the mechanisms. We can > > Yep, the fsync-happy numbers more or less match... at least for 2.6.37: > http://tinyurl.com/4q2xeao Good to hear. Thanks for the detailed testing. > I'll give 2.6.38-rc2 a try later, though -rc1 didn't boot for me, so these > numbers are based on a backport to .37. :( Well, there hasn' been any change in the area during the merge window anyway, so I think testing on 2.6.37 should be fine. > > I don't really think we should design the whole thing around broken > > devices which incorrectly report writeback cache when it need not. > > The correct place to work around that is during device identification > > not in the flush logic. > > elm3a4_sas and elm3c71_extsas advertise writeback cache yet the > flush completion times are suspiciously low. I suppose it could be > useful to disable flushes to squeeze out that last bit of > performance, though I don't know how one goes about querying the > disk array to learn if there's a battery behind the cache. I guess > the current mechanism (admin knob that picks a safe default) is good > enough. Yeap, that or a blacklist of devices which lie. Jens, what do you think? If you don't object, let's put this through linux-next. Thank you. -- tejun -- 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
