linux-kernel - Re: [PATCH 4/7] mm, vmscan: show LRU name in mm_vmscan_lru

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Date:   Tue, 3 Jan 2017 22:24:11 +0100
From:   Michal Hocko <mhocko@...nel.org>
To:     Vlastimil Babka <vbabka@...e.cz>
Cc:     linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
        Mel Gorman <mgorman@...e.de>,
        Johannes Weiner <hannes@...xchg.org>,
        Rik van Riel <riel@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4/7] mm, vmscan: show LRU name in mm_vmscan_lru_isolate
 tracepoint

On Tue 03-01-17 21:52:44, Michal Hocko wrote:
> On Tue 03-01-17 21:47:45, Michal Hocko wrote:
> > On Tue 03-01-17 18:08:58, Vlastimil Babka wrote:
> > > On 12/28/2016 04:30 PM, Michal Hocko wrote:
> > > > From: Michal Hocko <mhocko@...e.com>
> > > > 
> > > > mm_vmscan_lru_isolate currently prints only whether the LRU we isolate
> > > > from is file or anonymous but we do not know which LRU this is. It is
> > > > useful to know whether the list is file or anonymous as well. Change
> > > > the tracepoint to show symbolic names of the lru rather.
> > > > 
> > > > Signed-off-by: Michal Hocko <mhocko@...e.com>
> > > > ---
> > > >  include/trace/events/vmscan.h | 20 ++++++++++++++------
> > > >  mm/vmscan.c                   |  2 +-
> > > >  2 files changed, 15 insertions(+), 7 deletions(-)
> > > > 
> > > > diff --git a/include/trace/events/vmscan.h b/include/trace/events/vmscan.h
> > > > index 6af4dae46db2..cc0b4c456c78 100644
> > > > --- a/include/trace/events/vmscan.h
> > > > +++ b/include/trace/events/vmscan.h
> > > > @@ -36,6 +36,14 @@
> > > >  		(RECLAIM_WB_ASYNC) \
> > > >  	)
> > > > 
> > > > +#define show_lru_name(lru) \
> > > > +	__print_symbolic(lru, \
> > > > +			{LRU_INACTIVE_ANON, "LRU_INACTIVE_ANON"}, \
> > > > +			{LRU_ACTIVE_ANON, "LRU_ACTIVE_ANON"}, \
> > > > +			{LRU_INACTIVE_FILE, "LRU_INACTIVE_FILE"}, \
> > > > +			{LRU_ACTIVE_FILE, "LRU_ACTIVE_FILE"}, \
> > > > +			{LRU_UNEVICTABLE, "LRU_UNEVICTABLE"})
> > > > +
> > > 
> > > Does this work with external tools such as trace-cmd, i.e. does it export
> > > the correct format file?
> > 
> > How do I find out?
> 
> Well, I've just checked the format file and it says
> print fmt: "isolate_mode=%d classzone=%d order=%d nr_requested=%lu nr_scanned=%lu nr_skipped=%lu nr_taken=%lu lru=%s", REC->isolate_mode, REC->classzone_idx, REC->order, REC->nr_requested, REC->nr_scanned, REC->nr_skipped, REC->nr_taken, __print_symbolic(REC->lru, {LRU_INACTIVE_ANON, "LRU_INACTIVE_ANON"}, {LRU_ACTIVE_ANON, "LRU_ACTIVE_ANON"}, {LRU_INACTIVE_FILE, "LRU_INACTIVE_FILE"}, {LRU_ACTIVE_FILE, "LRU_ACTIVE_FILE"}, {LRU_UNEVICTABLE, "LRU_UNEVICTABLE"})
> 
> So the tool should be OK as long as it can find values for LRU_*
> constants. Is this what is the problem?

OK, I got it. We need enum->value translation and all the EM stuff to do
that, right?

I will rework the patch and move the definition to the rest of the EM
family...
-- 
Michal Hocko
SUSE Labs