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Message-ID: <20111229110850.GA5680@shutemov.name>
Date: Thu, 29 Dec 2011 13:08:50 +0200
From: "Kirill A. Shutemov" <kirill@...temov.name>
To: Michal Hocko <mhocko@...e.cz>
Cc: linux-mm@...ck.org, cgroups@...r.kernel.org,
linux-kernel@...r.kernel.org,
containers@...ts.linux-foundation.org,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
Balbir Singh <bsingharora@...il.com>,
Johannes Weiner <hannes@...xchg.org>,
Michal Marek <mmarek@...e.cz>, linux-kbuild@...r.kernel.org
Subject: Re: [PATCH] Makefiles: Disable unused-variable warning (was: Re:
[PATCH 1/6] memcg: fix unused variable warning)
On Thu, Dec 29, 2011 at 11:42:30AM +0100, Michal Hocko wrote:
> On Tue 27-12-11 20:26:13, Kirill A. Shutemov wrote:
> > On Tue, Dec 27, 2011 at 02:57:52PM +0100, Michal Hocko wrote:
> > > On Sat 24-12-11 05:00:14, Kirill A. Shutemov wrote:
> > > > From: "Kirill A. Shutemov" <kirill@...temov.name>
> > > >
> > > > mm/memcontrol.c: In function ‘memcg_check_events’:
> > > > mm/memcontrol.c:784:22: warning: unused variable ‘do_numainfo’ [-Wunused-variable]
> > > >
> > > > Signed-off-by: Kirill A. Shutemov <kirill@...temov.name>
> > > > ---
> > > > mm/memcontrol.c | 7 ++++---
> > > > 1 files changed, 4 insertions(+), 3 deletions(-)
> > > >
> > > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> > > > index d643bd6..a5e92bd 100644
> > > > --- a/mm/memcontrol.c
> > > > +++ b/mm/memcontrol.c
> > > > @@ -781,14 +781,15 @@ static void memcg_check_events(struct mem_cgroup *memcg, struct page *page)
> > > > /* threshold event is triggered in finer grain than soft limit */
> > > > if (unlikely(mem_cgroup_event_ratelimit(memcg,
> > > > MEM_CGROUP_TARGET_THRESH))) {
> > > > - bool do_softlimit, do_numainfo;
> > > > + bool do_softlimit;
> > > >
> > > > - do_softlimit = mem_cgroup_event_ratelimit(memcg,
> > > > - MEM_CGROUP_TARGET_SOFTLIMIT);
> > > > #if MAX_NUMNODES > 1
> > > > + bool do_numainfo;
> > > > do_numainfo = mem_cgroup_event_ratelimit(memcg,
> > > > MEM_CGROUP_TARGET_NUMAINFO);
> > > > #endif
> > > > + do_softlimit = mem_cgroup_event_ratelimit(memcg,
> > > > + MEM_CGROUP_TARGET_SOFTLIMIT);
> > >
> > > I don't like this very much. Maybe we should get rid of both do_* and
> > > do it with flags? But maybe it is not worth the additional code at
> > > all...
> >
> > Something like this (untested):
> > ====
> > From f57e1a2e1aaaa167c75b963d5bf12fcbdd3331b8 Mon Sep 17 00:00:00 2001
> > From: "Kirill A. Shutemov" <kirill@...temov.name>
> > Date: Tue, 27 Dec 2011 20:17:13 +0200
> > Subject: [PATCH] memcg: cleanup memcg_check_events()
> >
> > Signed-off-by: Kirill A. Shutemov <kirill@...temov.name>
>
> The patch looks correct but I am still not sure this is worth fixing in
> the code rather than disabling Wunused-variable.
Does it look better then original code from your POV?
It's a bit cleaner, I think.
>
> > ---
> > mm/memcontrol.c | 42 ++++++++++++++++++++++++------------------
> > 1 files changed, 24 insertions(+), 18 deletions(-)
> >
> > diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> > index d643bd6..40c2236 100644
> > --- a/mm/memcontrol.c
> > +++ b/mm/memcontrol.c
> > @@ -108,11 +108,12 @@ enum mem_cgroup_events_index {
> > * than using jiffies etc. to handle periodic memcg event.
> > */
> > enum mem_cgroup_events_target {
> > - MEM_CGROUP_TARGET_THRESH,
> > - MEM_CGROUP_TARGET_SOFTLIMIT,
> > - MEM_CGROUP_TARGET_NUMAINFO,
> > - MEM_CGROUP_NTARGETS,
> > + MEM_CGROUP_TARGET_THRESH = BIT(1),
> > + MEM_CGROUP_TARGET_SOFTLIMIT = BIT(2),
> > + MEM_CGROUP_TARGET_NUMAINFO = BIT(3),
> > };
> > +#define MEM_CGROUP_NTARGETS 3
> > +
> > #define THRESHOLDS_EVENTS_TARGET (128)
> > #define SOFTLIMIT_EVENTS_TARGET (1024)
> > #define NUMAINFO_EVENTS_TARGET (1024)
> > @@ -743,7 +744,7 @@ static unsigned long mem_cgroup_nr_lru_pages(struct mem_cgroup *memcg,
> > return total;
> > }
> >
> > -static bool mem_cgroup_event_ratelimit(struct mem_cgroup *memcg,
> > +static int mem_cgroup_event_ratelimit(struct mem_cgroup *memcg,
> > enum mem_cgroup_events_target target)
> > {
> > unsigned long val, next;
> > @@ -766,9 +767,9 @@ static bool mem_cgroup_event_ratelimit(struct mem_cgroup *memcg,
> > break;
> > }
> > __this_cpu_write(memcg->stat->targets[target], next);
> > - return true;
> > + return target;
> > }
> > - return false;
> > + return 0;
> > }
> >
> > /*
> > @@ -777,29 +778,34 @@ static bool mem_cgroup_event_ratelimit(struct mem_cgroup *memcg,
> > */
> > static void memcg_check_events(struct mem_cgroup *memcg, struct page *page)
> > {
> > + int flags;
> > +
> > preempt_disable();
> > - /* threshold event is triggered in finer grain than soft limit */
> > - if (unlikely(mem_cgroup_event_ratelimit(memcg,
> > - MEM_CGROUP_TARGET_THRESH))) {
> > - bool do_softlimit, do_numainfo;
> > + flags = mem_cgroup_event_ratelimit(memcg, MEM_CGROUP_TARGET_THRESH);
> >
> > - do_softlimit = mem_cgroup_event_ratelimit(memcg,
> > + /*
> > + * Threshold event is triggered in finer grain than soft limit
> > + * and numainfo
> > + */
> > + if (unlikely(flags)) {
> > + flags |= mem_cgroup_event_ratelimit(memcg,
> > MEM_CGROUP_TARGET_SOFTLIMIT);
> > #if MAX_NUMNODES > 1
> > - do_numainfo = mem_cgroup_event_ratelimit(memcg,
> > + flags |= mem_cgroup_event_ratelimit(memcg,
> > MEM_CGROUP_TARGET_NUMAINFO);
> > #endif
> > - preempt_enable();
> > + }
> > + preempt_enable();
> >
> > + if (unlikely(flags)) {
> > mem_cgroup_threshold(memcg);
> > - if (unlikely(do_softlimit))
> > + if (unlikely(flags & MEM_CGROUP_TARGET_SOFTLIMIT))
> > mem_cgroup_update_tree(memcg, page);
> > #if MAX_NUMNODES > 1
> > - if (unlikely(do_numainfo))
> > + if (unlikely(flags & MEM_CGROUP_TARGET_NUMAINFO))
> > atomic_inc(&memcg->numainfo_events);
> > #endif
> > - } else
> > - preempt_enable();
> > + }
> > }
> >
> > struct mem_cgroup *mem_cgroup_from_cont(struct cgroup *cont)
> > --
> > 1.7.7.3
>
> --
> Michal Hocko
> SUSE Labs
> SUSE LINUX s.r.o.
> Lihovarska 1060/12
> 190 00 Praha 9
> Czech Republic
--
Kirill A. Shutemov
--
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