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SubjectRe: [PATCH] mm: vmscan: drop may_writepage and classzone_idx from direct reclaim begin template
On Thu, Mar 14, 2019 at 6:19 PM Michal Hocko <mhocko@kernel.org> wrote:
>
> On Fri 01-03-19 14:24:12, Yafang Shao wrote:
> > There are three tracepoints using this template, which are
> > mm_vmscan_direct_reclaim_begin,
> > mm_vmscan_memcg_reclaim_begin,
> > mm_vmscan_memcg_softlimit_reclaim_begin.
> >
> > Regarding mm_vmscan_direct_reclaim_begin,
> > sc.may_writepage is !laptop_mode, that's a static setting, and
> > reclaim_idx is derived from gfp_mask which is already show in this
> > tracepoint.
> >
> > Regarding mm_vmscan_memcg_reclaim_begin,
> > may_writepage is !laptop_mode too, and reclaim_idx is (MAX_NR_ZONES-1),
> > which are both static value.
> >
> > mm_vmscan_memcg_softlimit_reclaim_begin is the same with
> > mm_vmscan_memcg_reclaim_begin.
> >
> > So we can drop them all.
>
> I agree. Although classzone_idx is PITA to calculate nothing really
> prevents us to have a tool to do that. may_writepage is not all that
> useful anymore.
>
> > Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
>
> From a quick glance this looks ok. I haven't really checked deeply or
> tried to compile it but the change makes sense.
>

Thanks for your quick response!
This patch works fine, I have verified it.

> Acked-by: Michal Hocko <mhocko@suse.com>
> > ---
> > include/trace/events/vmscan.h | 26 ++++++++++----------------
> > mm/vmscan.c | 14 +++-----------
> > 2 files changed, 13 insertions(+), 27 deletions(-)
> >
> > diff --git a/include/trace/events/vmscan.h b/include/trace/events/vmscan.h
> > index a1cb913..153d90c 100644
> > --- a/include/trace/events/vmscan.h
> > +++ b/include/trace/events/vmscan.h
> > @@ -105,51 +105,45 @@
> >
> > DECLARE_EVENT_CLASS(mm_vmscan_direct_reclaim_begin_template,
> >
> > - TP_PROTO(int order, int may_writepage, gfp_t gfp_flags, int classzone_idx),
> > + TP_PROTO(int order, gfp_t gfp_flags),
> >
> > - TP_ARGS(order, may_writepage, gfp_flags, classzone_idx),
> > + TP_ARGS(order, gfp_flags),
> >
> > TP_STRUCT__entry(
> > __field( int, order )
> > - __field( int, may_writepage )
> > __field( gfp_t, gfp_flags )
> > - __field( int, classzone_idx )
> > ),
> >
> > TP_fast_assign(
> > __entry->order = order;
> > - __entry->may_writepage = may_writepage;
> > __entry->gfp_flags = gfp_flags;
> > - __entry->classzone_idx = classzone_idx;
> > ),
> >
> > - TP_printk("order=%d may_writepage=%d gfp_flags=%s classzone_idx=%d",
> > + TP_printk("order=%d gfp_flags=%s",
> > __entry->order,
> > - __entry->may_writepage,
> > - show_gfp_flags(__entry->gfp_flags),
> > - __entry->classzone_idx)
> > + show_gfp_flags(__entry->gfp_flags))
> > );
> >
> > DEFINE_EVENT(mm_vmscan_direct_reclaim_begin_template, mm_vmscan_direct_reclaim_begin,
> >
> > - TP_PROTO(int order, int may_writepage, gfp_t gfp_flags, int classzone_idx),
> > + TP_PROTO(int order, gfp_t gfp_flags),
> >
> > - TP_ARGS(order, may_writepage, gfp_flags, classzone_idx)
> > + TP_ARGS(order, gfp_flags)
> > );
> >
> > #ifdef CONFIG_MEMCG
> > DEFINE_EVENT(mm_vmscan_direct_reclaim_begin_template, mm_vmscan_memcg_reclaim_begin,
> >
> > - TP_PROTO(int order, int may_writepage, gfp_t gfp_flags, int classzone_idx),
> > + TP_PROTO(int order, gfp_t gfp_flags),
> >
> > - TP_ARGS(order, may_writepage, gfp_flags, classzone_idx)
> > + TP_ARGS(order, gfp_flags)
> > );
> >
> > DEFINE_EVENT(mm_vmscan_direct_reclaim_begin_template, mm_vmscan_memcg_softlimit_reclaim_begin,
> >
> > - TP_PROTO(int order, int may_writepage, gfp_t gfp_flags, int classzone_idx),
> > + TP_PROTO(int order, gfp_t gfp_flags),
> >
> > - TP_ARGS(order, may_writepage, gfp_flags, classzone_idx)
> > + TP_ARGS(order, gfp_flags)
> > );
> > #endif /* CONFIG_MEMCG */
> >
> > diff --git a/mm/vmscan.c b/mm/vmscan.c
> > index ac4806f..cdc0305 100644
> > --- a/mm/vmscan.c
> > +++ b/mm/vmscan.c
> > @@ -3304,10 +3304,7 @@ unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
> > if (throttle_direct_reclaim(sc.gfp_mask, zonelist, nodemask))
> > return 1;
> >
> > - trace_mm_vmscan_direct_reclaim_begin(order,
> > - sc.may_writepage,
> > - sc.gfp_mask,
> > - sc.reclaim_idx);
> > + trace_mm_vmscan_direct_reclaim_begin(order, sc.gfp_mask);
> >
> > nr_reclaimed = do_try_to_free_pages(zonelist, &sc);
> >
> > @@ -3338,9 +3335,7 @@ unsigned long mem_cgroup_shrink_node(struct mem_cgroup *memcg,
> > (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK);
> >
> > trace_mm_vmscan_memcg_softlimit_reclaim_begin(sc.order,
> > - sc.may_writepage,
> > - sc.gfp_mask,
> > - sc.reclaim_idx);
> > + sc.gfp_mask);
> >
> > /*
> > * NOTE: Although we can get the priority field, using it
> > @@ -3389,10 +3384,7 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
> >
> > zonelist = &NODE_DATA(nid)->node_zonelists[ZONELIST_FALLBACK];
> >
> > - trace_mm_vmscan_memcg_reclaim_begin(0,
> > - sc.may_writepage,
> > - sc.gfp_mask,
> > - sc.reclaim_idx);
> > + trace_mm_vmscan_memcg_reclaim_begin(0, sc.gfp_mask);
> >
> > psi_memstall_enter(&pflags);
> > noreclaim_flag = memalloc_noreclaim_save();
> > --
> > 1.8.3.1
> >
>
> --
> Michal Hocko
> SUSE Labs

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