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From:   Yafang Shao <laoar.shao@gmail.com>
Date:   Thu, 14 Mar 2019 17:43:36 +0800
Message-ID: <CALOAHbCf-HU4NJ3hp9Cozuy03aVqbOpzNi7+QWNU0AC1Q2tOMA@mail.gmail.com>
Subject: Re: [PATCH] mm: vmscan: drop may_writepage and classzone_idx from
 direct reclaim begin template
To:     Vlastimil Babka <vbabka@suse.cz>, Michal Hocko <mhocko@suse.com>,
        Souptick Joarder <jrdr.linux@gmail.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Linux MM <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>, shaoyafang@didiglobal.com
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Sender: linux-kernel-owner@vger.kernel.org
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On Fri, Mar 1, 2019 at 2:24 PM Yafang Shao <laoar.shao@gmail.com> 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.
>
> Signed-off-by: Yafang Shao <laoar.shao@gmail.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
>

Hi Vlastimil, Michal,

Any comments on this patch ?

Thanks
Yafang