On Tue, Jan 25, 2011 at 12:39:24PM +0100, Jens Axboe wrote: > On 2011-01-25 11:21, Tejun Heo wrote: > > 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. > > I like the approach, I'll queue it up for 2.6.39. Is this patch set still on the merge list for 2.6.39? --D > > -- > Jens Axboe > -- 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
