On Mon, Sep 05, 2011 at 10:16:07AM +0900, Daisuke Nishimura wrote:
> On Mon, 5 Sep 2011 08:59:13 +0900
> KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote:
>
> > On Sun, 4 Sep 2011 04:15:33 +0300
> > "Kirill A. Shutemov" <kirill@xxxxxxxxxxxxx> wrote:
> >
> > > From: "Kirill A. Shutemov" <kirill@xxxxxxxxxxxxx>
> > >
> > > Currently, mem_cgroup_usage() for non-root cgroup returns usage
> > > including stocks.
> > >
> > > Let's drain all socks before read resource counter value. It makes
> > > memory{,.memcg}.usage_in_bytes and memory.stat consistent.
> > >
> > > Signed-off-by: Kirill A. Shutemov <kirill@xxxxxxxxxxxxx>
> >
> > Hmm. This seems costly to me.
> >
> > If a user chesk usage_in_bytes in a memcg once per 1sec,
> > the kernel will call schedule_work on cpus once per 1sec.
> > So, IMHO, I don't like this.
> >
> I agree.
>
> We discussed a similar topic on the thread https://lkml.org/lkml/2011/3/18/212.
> And, we added the memory.txt:
> ---
> 5.5 usage_in_bytes
>
> For efficiency, as other kernel components, memory cgroup uses some optimization
> to avoid unnecessary cacheline false sharing. usage_in_bytes is affected by the
> method and doesn't show 'exact' value of memory(and swap) usage, it's an fuzz
> value for efficient access. (Of course, when necessary, it's synchronized.)
> If you want to know more exact memory usage, you should use RSS+CACHE(+SWAP)
> value in memory.stat(see 5.2).
> ---
Agree, thanks.
Should we have field 'ram' (or 'memory') for rss+cache in memory.stat?
--
Kirill A. Shutemov
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxx. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>