On Mon, Mar 28, 2011 at 11:08:15PM +0800, Jan Kara wrote: > On Mon 28-03-11 10:44:45, Wu Fengguang wrote: > > Hi Jan, > > > > On Sat, Mar 26, 2011 at 07:05:44AM +0800, Jan Kara wrote: > > > Hello Fengguang, > > > > > > On Fri 25-03-11 21:44:11, Wu Fengguang wrote: > > > > On Wed, Mar 23, 2011 at 05:43:14AM +0800, Jan Kara wrote: > > > > > Hello Fengguang, > > > > > > > > > > On Fri 18-03-11 22:30:01, Wu Fengguang wrote: > > > > > > On Wed, Mar 09, 2011 at 06:31:10AM +0800, Jan Kara wrote: > > > > > > > > > > > > > > Hello, > > > > > > > > > > > > > > I'm posting second version of my IO-less balance_dirty_pages() patches. This > > > > > > > is alternative approach to Fengguang's patches - much simpler I believe (only > > > > > > > 300 lines added) - but obviously I does not provide so sophisticated control. > > > > > > > > > > > > Well, it may be too early to claim "simplicity" as an advantage, until > > > > > > you achieve the following performance/feature comparability (most of > > > > > > them are not optional ones). AFAICS this work is kind of heavy lifting > > > > > > that will consume a lot of time and attention. You'd better find some > > > > > > more fundamental needs before go on the reworking. > > > > > > > > > > > > (1) latency > > > > > > (2) fairness > > > > > > (3) smoothness > > > > > > (4) scalability > > > > > > (5) per-task IO controller > > > > > > (6) per-cgroup IO controller (TBD) > > > > > > (7) free combinations of per-task/per-cgroup and bandwidth/priority controllers > > > > > > (8) think time compensation > > > > > > (9) backed by both theory and tests > > > > > > (10) adapt pause time up on 100+ dirtiers > > > > > > (11) adapt pause time down on low dirty pages > > > > > > (12) adapt to new dirty threshold/goal > > > > > > (13) safeguard against dirty exceeding > > > > > > (14) safeguard against device queue underflow > > > > > I think this is a misunderstanding of my goals ;). My main goal is to > > > > > explore, how far we can get with a relatively simple approach to IO-less > > > > > balance_dirty_pages(). I guess what I have is better than the current > > > > > balance_dirty_pages() but it sure does not even try to provide all the > > > > > features you try to provide. > > > > > > > > OK. > > > > > > > > > I'm thinking about tweaking ratelimiting logic to reduce latencies in some > > > > > tests, possibly add compensation when we waited for too long in > > > > > balance_dirty_pages() (e.g. because of bumpy IO completion) but that's > > > > > about it... > > > > > > > > > > Basically I do this so that we can compare and decide whether what my > > > > > simple approach offers is OK or whether we want some more complex solution > > > > > like your patches... > > > > > > > > Yeah, now both results are on the website. Let's see whether they are > > > > acceptable for others. > > > Yes. BTW, I think we'll discuss this at LSF so it would be beneficial if > > > we both prepared a fairly short explanation of our algorithm and some > > > summary of the measured results. I think it would be good to keep each of > > > us below 5 minutes so that we don't bore the audience - people will ask for > > > details where they are interested... What do you think? > > That looks good, however I'm not able to attend LSF this year, would > > you help show my slides? > Ah, that's a pity :(. If you send me a few slides I can show them, that's > no problem. I'll also try to understand your patches in enough detail so > that I can answer possible questinons but author is always the best to > present his work :). Thank you very much :) > > > I'll try to run also your patches on my setup to see how they work :) V6 > > > from your website is the latest version, isn't it? > > > > Thank you. You can run > > http://git.kernel.org/?p=linux/kernel/git/wfg/writeback.git;a=shortlog;h=refs/heads/dirty-throttling-v6 > > or > > http://www.kernel.org/pub/linux/kernel/people/wfg/writeback/dirty-throttling-v6/dirty-throttling-v6-2.6.38-rc6.patch > > whatever convenient for you. > > > > If you are ready with v3, I can also help test it out and do some > > comparison on the results. > I have done a couple of smaller fixes but I don't expect them to affect > performance in the loads we use. But I'll send you the patches when I > implement some significant change (but for that I need to reproduce the > latencies you sometimes see first...). OK. I can conveniently test the single disk cases. For JBOD and RAID cases, I don't own the servers so normally have to wait for some time before being able to carry out the tests.. Thanks, Fengguang -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
