On Thu, 2011-05-12 at 10:27 -0500, Christoph Lameter wrote: > On Thu, 12 May 2011, James Bottomley wrote: > > > > > */ > > > > static int slub_min_order; > > > > -static int slub_max_order = PAGE_ALLOC_COSTLY_ORDER; > > > > +static int slub_max_order; > > > > > > If we really need to do this then do not push this down to zero please. > > > SLAB uses order 1 for the meax. Lets at least keep it theere. > > > > 1 is the current value. Reducing it to zero seems to fix the kswapd > > induced hangs. The problem does look to be some shrinker/allocator > > interference somewhere in vmscan.c, but the fact is that it's triggered > > by SLUB and not SLAB. I really think that what's happening is some type > > of feedback loops where one of the shrinkers is issuing a > > wakeup_kswapd() so kswapd never sleeps (and never relinquishes the CPU > > on non-preempt). > > The current value is PAGE_ALLOC_COSTLY_ORDER which is 3. > > > > We have been using SLUB for a long time. Why is this issue arising now? > > > Due to compaction etc making reclaim less efficient? > > > > This is the snark argument (I've said it thrice the bellman cried and > > what I tell you three times is true). The fact is that no enterprise > > distribution at all uses SLUB. It's only recently that the desktop > > distributions started to ... the bugs are showing up under FC15 beta, > > which is the first fedora distribution to enable it. I'd say we're only > > just beginning widespread SLUB testing. > > Debian and Ubuntu have been using SLUB for a long time Only from Squeeze, which has been released for ~3 months. That doesn't qualify as a "long time" in my book. > (and AFAICT from my > archives so has Fedora). As I said above, no released fedora version uses SLUB. It's only just been enabled for the unreleased FC15; I'm testing a beta copy. > I have been running those here for a couple of > years and the issues that I see here seem to be only with the most > recent kernels that now do compaction and other reclaim tricks. but a sample of one doeth not great testing make. However, since you admit even you see problems, let's concentrate on fixing them rather than recriminations? James -- 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
