Re: Reading /proc/slabinfo causes stalls

2012-10-16 Thread Christoph Lameter
On Tue, 16 Oct 2012, Avleen Vig wrote: > There were some concerns that it doesn't perform as well as SLAB on > large hardware (we're almost always running >16G RAM, and regularly > >96G RAM on things like memcache servers). > If the performance pans out, SLUB would be great. We have been using SL

Re: Reading /proc/slabinfo causes stalls

2012-10-16 Thread Avleen Vig
On Tue, Oct 16, 2012 at 1:55 PM, Christoph Lameter wrote: > On Tue, 16 Oct 2012, David Rientjes wrote: > >> Or convert slab_mutex to be a rwlock? > > The RT folks just converted it to a mutex ;-) Damn :-) I'll play around with SLUB. There were some concerns that it doesn't perform as well as

Re: Reading /proc/slabinfo causes stalls

2012-10-16 Thread Christoph Lameter
On Tue, 16 Oct 2012, David Rientjes wrote: > Or convert slab_mutex to be a rwlock? The RT folks just converted it to a mutex ;-) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vge

Re: Reading /proc/slabinfo causes stalls

2012-10-16 Thread David Rientjes
On Tue, 16 Oct 2012, Christoph Lameter wrote: > If the allocator is SLAB then I would think that this is a stall of > slabinfo mutex vs. slab clean operations (gets more frequent the more > processors are in the box). > > If this is the case then using the SLUB allocator will fix the issue since

Re: Reading /proc/slabinfo causes stalls

2012-10-16 Thread Christoph Lameter
On Tue, 16 Oct 2012, Pekka Enberg wrote: > > Is this a known condition? Are there work arounds or other ways to get the > > slab allocation data which don't cause stalls? > > What kernel version are you using? What does your .config look like? slabinfo access requires a mutex which will stall cer

Re: Reading /proc/slabinfo causes stalls

2012-10-16 Thread Avleen Vig
By default we use the 2.6.32-279.5.2 as provided by CentOS. However I also tried the 3.0.46 from elrepo: http://elrepo.org/linux/kernel/el6/x86_64/RPMS/ The config for the 3.0 kernel is: https://gist.github.com/3901068 They both seem to exhibit the same problem. Thanks :) On Tue, Oct 16, 2012 a

Re: Reading /proc/slabinfo causes stalls

2012-10-16 Thread Pekka Enberg
Hi Avleen, On Tue, Oct 16, 2012 at 8:51 PM, Avleen Vig wrote: > I *think* this is the right place to ask this, and apologies if it's not > (is there a better place?). > > We have checks which read /proc/slabinfo once a minute, and have noticed > that this causes the entire system to stall for a f