Messages in this thread | | | Date | Mon, 28 Apr 2008 23:33:05 +0530 | From | Balbir Singh <> | Subject | Re: [RFC][-mm] [2/2] Simple stats for memory resource controller |
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Andrew Morton wrote: > On Mon, 28 Apr 2008 21:30:29 +0530 Balaji Rao <balajirrao@gmail.com> wrote: > >> On Monday 14 April 2008 08:09:48 pm Balbir Singh wrote: >>> Balaji Rao wrote: >>>> This patch implements trivial statistics for the memory resource controller. >>>> >>>> Signed-off-by: Balaji Rao <balajirrao@gmail.com> >>>> CC: Balbir Singh <balbir@linux.vnet.ibm.com> >>>> CC: Dhaval Giani <dhaval@linux.vnet.ibm.com> >>>> >>>> diff --git a/mm/memcontrol.c b/mm/memcontrol.c >>>> index a860765..ca98b21 100644 >>>> --- a/mm/memcontrol.c >>>> +++ b/mm/memcontrol.c >>>> @@ -47,6 +47,8 @@ enum mem_cgroup_stat_index { >>>> */ >>>> MEM_CGROUP_STAT_CACHE, /* # of pages charged as cache */ >>>> MEM_CGROUP_STAT_RSS, /* # of pages charged as rss */ >>>> + MEM_CGROUP_STAT_PGPGIN_COUNT, /* # of pages paged in */ >>>> + MEM_CGROUP_STAT_PGPGOUT_COUNT, /* # of pages paged out */ >>>> >>>> MEM_CGROUP_STAT_NSTATS, >>>> }; >>>> @@ -198,6 +200,13 @@ static void mem_cgroup_charge_statistics(struct mem_cgroup *mem, int flags, >>>> __mem_cgroup_stat_add_safe(stat, MEM_CGROUP_STAT_CACHE, val); >>>> else >>>> __mem_cgroup_stat_add_safe(stat, MEM_CGROUP_STAT_RSS, val); >>>> + >>>> + if (charge) >>>> + __mem_cgroup_stat_add_safe(stat, >>>> + MEM_CGROUP_STAT_PGPGIN_COUNT, 1); >>>> + else >>>> + __mem_cgroup_stat_add_safe(stat, >>>> + MEM_CGROUP_STAT_PGPGOUT_COUNT, 1); >>>> } >>>> >>>> static struct mem_cgroup_per_zone * >>>> @@ -897,6 +906,8 @@ static const struct mem_cgroup_stat_desc { >>>> } mem_cgroup_stat_desc[] = { >>>> [MEM_CGROUP_STAT_CACHE] = { "cache", PAGE_SIZE, }, >>>> [MEM_CGROUP_STAT_RSS] = { "rss", PAGE_SIZE, }, >>>> + [MEM_CGROUP_STAT_PGPGIN_COUNT] = {"pgpgin", 1, }, >>>> + [MEM_CGROUP_STAT_PGPGOUT_COUNT] = {"pgpgout", 1, }, >>>> }; >>>> >>>> static int mem_control_stat_show(struct cgroup *cont, struct cftype *cft, >>>> >>> Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com> >>> >>> Hi, Andrew, >>> >>> Could you please include these statistics in -mm. >>> >>> Balbir >>> >>> >> Hi Andrew, >> >> Now that Balbir Singh has ACKed it, could you please include it in -mm ? > > <looks> > > I guess we can add this one, sure. But [patch 1/2] needs work. > > - The local_irq_save()-around-for_each_possible_cpu() locking doesn't > make sense. >
Yes, that needs re-work. Peter Zijlstra had detailed review comments for the patch
> - indenting is busted in account_user_time() and account_system_time() > > - The use of for_each_possible_cpu() can be grossly inefficient. It > would be preferred to use for_each_possible_cpu() and add a cpu-hotplug > notifier. > > - The proposed newly-added userspace interfaces are undocumented >
Yes, we need more documentation
> - The changelogs don't explain why we might want this feature in Linux. >
We need more accurate utime/stime per cgroup. Summing them in user space is insufficient, since tasks can move across groups and what we have is accumulated time per task.
> - Generally: there are a heck of a lot of different ways of accounting > for things in core kernel and it's really sad to see yet another one > being added. >
We thought of summing up stuff in user space, we've look harder. The plan is to finally send all the data using cgroupstats.
> > Actually, [patch 2/2] adds new kerenl->user interfaces and doesn't document > them. But afaict the existing memcgroup stats are secret too. >
The statistics was added as a part of git commit d52aa412d43827033a8e2ce4415ef6e8f8d53635. I'll go ahead and try to document them. These patches piggy back on the statistics patches and add pagein/pageout counts, which is a useful statistic for the memory controller.
-- Warm Regards, Balbir Singh Linux Technology Center IBM, ISTL
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