Messages in this thread | | | Date | Wed, 20 Jul 2011 17:50:29 +0400 | From | Konstantin Khlebnikov <> | Subject | Re: [PATCH] mm-slab: allocate kmem_cache with __GFP_REPEAT |
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Pekka Enberg wrote: > On Wed, 20 Jul 2011, Konstantin Khlebnikov wrote: >>> The changelog isn't that convincing, really. This is kmem_cache_create() >>> so I'm surprised we'd ever get NULL here in practice. Does this fix some >>> problem you're seeing? If this is really an issue, I'd blame the page >>> allocator as GFP_KERNEL should just work. >> >> nf_conntrack creates separate slab-cache for each net-namespace, >> this patch of course not eliminates the chance of failure, but makes it more >> acceptable. > > I'm still surprised you are seeing failures. mm/slab.c hasn't changed > significantly in a long time. Why hasn't anyone reported this before? I'd > still be inclined to shift the blame to the page allocator... Mel, > Christoph? > > On Wed, 20 Jul 2011, Konstantin Khlebnikov wrote: >> struct kmem_size for slub is more compact, it uses pecpu-pointers instead of >> dumb NR_CPUS-size array. >> probably better to fix this side... > > So how big is 'struct kmem_cache' for your configuration anyway? Fixing > the per-cpu data structures would be nice but I'm guessing it'll be > slightly painful for mm/slab.c.
With NR_CPUS=4096 and MAX_NUMNODES=512 its over 9k! so it require order-4 page, meanwhile PAGE_ALLOC_COSTLY_ORDER is 3
> > Pekka
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