lkml.org 
[lkml]   [2012]   [Jun]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH v2] tmpfs not interleaving properly
    (6/19/12 7:21 PM), Nathan Zimmer wrote:
    > On Fri, Jun 01, 2012 at 01:22:15PM -0400, KOSAKI Motohiro wrote:
    >> (6/1/12 10:24 AM), Nathan Zimmer wrote:
    >>> On Thu, May 31, 2012 at 04:35:53PM -0400, KOSAKI Motohiro wrote:
    >>>> (5/31/12 4:25 PM), Andrew Morton wrote:
    >>>>> On Thu, 31 May 2012 16:09:15 -0400
    >>>>> KOSAKI Motohiro<kosaki.motohiro@gmail.com> wrote:
    >>>>>
    >>>>>>> --- a/mm/shmem.c
    >>>>>>> +++ b/mm/shmem.c
    >>>>>>> @@ -929,7 +929,7 @@ static struct page *shmem_alloc_page(gfp_t gfp,
    >>>>>>> /*
    >>>>>>> * alloc_page_vma() will drop the shared policy reference
    >>>>>>> */
    >>>>>>> - return alloc_page_vma(gfp,&pvma, 0);
    >>>>>>> + return alloc_page_vma(gfp,&pvma, info->node_offset<< PAGE_SHIFT );
    >>>>>>
    >>>>>> 3rd argument of alloc_page_vma() is an address. This is type error.
    >>>>>
    >>>>> Well, it's an unsigned long...
    >>>>>
    >>>>> But yes, it is conceptually wrong and *looks* weird. I think we can
    >>>>> address that by overcoming our peculair aversion to documenting our
    >>>>> code, sigh. This?
    >>>>
    >>>> Sorry, no.
    >>>>
    >>>> addr agrument of alloc_pages_vma() have two meanings.
    >>>>
    >>>> 1) interleave node seed
    >>>> 2) look-up key of shmem policy
    >>>>
    >>>> I think this patch break (2). shmem_get_policy(pol, addr) assume caller honor to
    >>>> pass correct address.
    >>>
    >>> But the pseudo vma we generated in shmem_alloc_page the vm_ops are set to NULL.
    >>> So get_vma_policy will return the policy provided by the pseudo vma and not reach
    >>> the shmem_get_policy.
    >>
    >> yes, and it is bug source. we may need to change soon. I guess the right way is
    >> to make vm_ops->interleave and interleave_nid uses it if povided.
    >
    > If we provide vm_ops then won't shmem_get_policy get called?
    > That would be an issue since shmem_get_policy assumes vm_file is non NULL.
    >
    >> btw, I don't think node_random() is good idea. it is random(pid + jiffies + cycle).
    >> current->cpuset_mem_spread_rotor is per-thread value. but you now need per-inode
    >> interleave offset. maybe, just inode addition is enough. Why do you need randomness?
    >
    > I don't really need the randomness, the rotor should be good enough.
    > The correct way to get that is cpuset_mem_spread_node(), yes?

    I think that's good idea too.


    \
     
     \ /
      Last update: 2012-06-20 06:41    [W:0.029 / U:35.084 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site