lkml.org 
[lkml]   [2011]   [Jan]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    SubjectRe: [BUGFIX][PATCH 1/4] memcg: fix limit estimation at reclaim for hugepage
    On Fri, 28 Jan 2011 12:24:49 +0900
    KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:

    > From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
    >
    > Current memory cgroup's code tends to assume page_size == PAGE_SIZE
    > and arrangement for THP is not enough yet.
    >
    > This is one of fixes for supporing THP. This adds
    > mem_cgroup_check_margin() and checks whether there are required amount of
    > free resource after memory reclaim. By this, THP page allocation
    > can know whether it really succeeded or not and avoid infinite-loop
    > and hangup.
    >
    > Total fixes for do_charge()/reclaim memory will follow this patch.
    >
    > Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

    This patch looks good to me, but some nitpicks.

    > ---
    > include/linux/res_counter.h | 11 +++++++++++
    > mm/memcontrol.c | 25 ++++++++++++++++++++++++-
    > 2 files changed, 35 insertions(+), 1 deletion(-)
    >
    > Index: mmotm-0125/include/linux/res_counter.h
    > ===================================================================
    > --- mmotm-0125.orig/include/linux/res_counter.h
    > +++ mmotm-0125/include/linux/res_counter.h
    > @@ -182,6 +182,17 @@ static inline bool res_counter_check_und
    > return ret;
    > }
    >
    > +static inline s64 res_counter_check_margin(struct res_counter *cnt)
    > +{
    > + s64 ret;
    > + unsigned long flags;
    > +
    > + spin_lock_irqsave(&cnt->lock, flags);
    > + ret = cnt->limit - cnt->usage;
    > + spin_unlock_irqrestore(&cnt->lock, flags);
    > + return ret;
    > +}
    > +
    > static inline bool res_counter_check_under_soft_limit(struct res_counter *cnt)
    > {
    > bool ret;
    > Index: mmotm-0125/mm/memcontrol.c
    > ===================================================================
    > --- mmotm-0125.orig/mm/memcontrol.c
    > +++ mmotm-0125/mm/memcontrol.c
    > @@ -1111,6 +1111,22 @@ static bool mem_cgroup_check_under_limit
    > return false;
    > }
    >
    > +static s64 mem_cgroup_check_margin(struct mem_cgroup *mem)
    > +{
    > + s64 mem_margin;
    > +
    > + if (do_swap_account) {
    > + s64 memsw_margin;
    > +
    > + mem_margin = res_counter_check_margin(&mem->res);
    > + memsw_margin = res_counter_check_margin(&mem->memsw);
    > + if (mem_margin > memsw_margin)
    > + mem_margin = memsw_margin;
    > + } else
    > + mem_margin = res_counter_check_margin(&mem->res);
    > + return mem_margin;
    > +}
    > +
    How about

    mem_margin = res_counter_check_margin(&mem->res);
    if (do_swap_account)
    memsw_margin = res_counter_check_margin(&mem->memsw);
    else
    memsw_margin = RESOURCE_MAX;

    return min(mem_margin, memsw_margin);

    ?
    I think using min() makes it more clear what this function does.

    > static unsigned int get_swappiness(struct mem_cgroup *memcg)
    > {
    > struct cgroup *cgrp = memcg->css.cgroup;
    > @@ -1853,7 +1869,14 @@ static int __mem_cgroup_do_charge(struct
    > * Check the limit again to see if the reclaim reduced the
    > * current usage of the cgroup before giving up
    > */
    > - if (ret || mem_cgroup_check_under_limit(mem_over_limit))
    > + if (mem_cgroup_check_margin(mem_over_limit) >= csize)
    > + return CHARGE_RETRY;
    > +
    > + /*
    > + * If the charge size is a PAGE_SIZE, it's not hopeless while
    > + * we can reclaim a page.
    > + */
    > + if (csize == PAGE_SIZE && ret)
    > return CHARGE_RETRY;
    >
    > /*
    >
    checkpatch complains some whitespace warnings.


    Thanks,
    Daisuke Nishimura.


    \
     
     \ /
      Last update: 2011-01-28 05:53    [W:0.030 / U:31.564 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site