[lkml]   [2008]   [May]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectRe: [RFC][-mm] Simple stats for cpu resource controller v3
    On Sat, 3 May 2008 05:26:46 +0530
    Balaji Rao <> wrote:

    > > yes, that would be good.
    > OK, so when does account_system_time get called for the first time ? after
    > IRQs are set up, is it ? So, where do we place the hook ?

    Don't know - I'd need to dive in and work that out, and it's probably
    better than you do this..

    > Here's the patch.
    > diff --git a/include/linux/percpu_counter.h b/include/linux/percpu_counter.h
    > index 9007ccd..8a1b756 100644
    > --- a/include/linux/percpu_counter.h
    > +++ b/include/linux/percpu_counter.h
    > @@ -21,7 +21,7 @@ struct percpu_counter {
    > struct list_head list; /* All percpu_counters are on a list */
    > #endif
    > - s32 *counters;
    > + s32 counters[NR_CPUS];
    > };

    Please, no. That's a 4092-byte increase in sizeof(struct percpu_counter).
    Hence a 12 kbyte increase in sizeof(struct ext3_sb_info). Let's just sort
    out the cgroup startup ordering.

    <looks at __percpu_alloc_mask>
    <wanders off-topic>

    Eric, is that optimal? alloc_percpu() will pass down cpu_possible_map in
    `mask', and we only need to allocate enough slots to cover the
    highest-set-bit in cpu_possible_map. However the implementation ignores
    `mask' and does

    size_t sz = roundup(nr_cpu_ids * sizeof(void *), cache_line_size());
    void *pdata = kzalloc(sz, gfp);

    Now, if the highest-set-bit in cpu_possible_map is always equal to
    (1<<nr_cpu_ids) then it doesn't matter. But is that the case?

    (If someone calls __percpu_alloc_mask with something that has less bits set
    than cpu_possible_map then it surely is wasteful, but that sounds

     \ /
      Last update: 2008-05-03 02:23    [W:0.022 / U:70.204 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site