Re: [PATCH v3] memcg: Add memory.pressure_level events

Anton Vorontsov
2013-04-03T04:04:43Z

On Wed, Mar 27, 2013 at 10:53:30AM +0900, Kamezawa Hiroyuki wrote:
[...]
> >+++ b/mm/memcontrol.c
> >@@ -49,6 +49,7 @@
> > #include <linux/fs.h>
> > #include <linux/seq_file.h>
> > #include <linux/vmalloc.h>
> >+#include <linux/vmpressure.h>
> > #include <linux/mm_inline.h>
> > #include <linux/page_cgroup.h>
> > #include <linux/cpu.h>
> >@@ -376,6 +377,9 @@ struct mem_cgroup {
> > atomic_t numainfo_events;
> > atomic_t numainfo_updating;
> > #endif
> >+
> >+ struct vmpressure vmpr;
> >+
>
> How about placing this just below "memsw_threshold" ?
> memory objects around there is not performance critical.

Yup, done.

[...]
> >+static const unsigned int vmpressure_win = SWAP_CLUSTER_MAX * 16;
> >+static const unsigned int vmpressure_level_med = 60;
> >+static const unsigned int vmpressure_level_critical = 95;
> >+static const unsigned int vmpressure_level_critical_prio = 3;
> >+
> more comments are welcomed...
>
> I'm not against the numbers themselves but I'm not sure how these numbers are
> selected...I'm glad if you show some reasons in changelog or somewhere.

Sure, in v4 the numbers are described in the comments.

[...]
> >+static enum vmpressure_levels vmpressure_calc_level(unsigned int scanned,
> >+ unsigned int reclaimed)
> >+{
> >+ unsigned long scale = scanned + reclaimed;
> >+ unsigned long pressure;
> >+
> >+ if (!scanned)
> >+ return VMPRESSURE_LOW;
>
> Can you add comment here ? When !scanned happens ?

Yeah, the comment is needed. in v4 I added explanation for this case.

[...]
> >+ mutex_lock(&vmpr->sr_lock);
> >+ vmpr->scanned += scanned;
> >+ vmpr->reclaimed += reclaimed;
> >+ mutex_unlock(&vmpr->sr_lock);
> >+
> >+ if (scanned < vmpressure_win || work_pending(&vmpr->work))
> >+ return;
> >+ schedule_work(&vmpr->work);
> >+}
>
> I'm not sure how other guys thinks but....could you place the definition
> of work_fn above calling it ? you call vmpressure_wk_fn(), right ?

Yup. OK, I rearranged the code a bit.

[...]
> > do {
> >+ vmpressure_prio(sc->gfp_mask, sc->target_mem_cgroup,
> >+ sc->priority);
> > sc->nr_scanned = 0;
> > aborted_reclaim = shrink_zones(zonelist, sc);
> >
> >
>
> When you answers Andrew's comment and fix problems, feel free to add
>
> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

Thanks a lot for the reviews, Kamezawa!

Anton