lkml.org 
[lkml]   [2011]   [Jul]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH] mm-slab: allocate kmem_cache with __GFP_REPEAT
    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



    \
     
     \ /
      Last update: 2011-07-20 15:53    [W:2.537 / U:0.076 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site