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[195.135.220.15]) by mx.google.com with ESMTPS id z12si472174edz.345.2019.02.28.02.17.32 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 28 Feb 2019 02:17:32 -0800 (PST) Received-SPF: softfail (google.com: domain of transitioning mhocko@kernel.org does not designate 195.135.220.15 as permitted sender) client-ip=195.135.220.15; Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning mhocko@kernel.org does not designate 195.135.220.15 as permitted sender) smtp.mailfrom=mhocko@kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=kernel.org X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id AD721AD73; Thu, 28 Feb 2019 10:17:31 +0000 (UTC) Date: Thu, 28 Feb 2019 11:17:30 +0100 From: Michal Hocko To: Yafang Shao Cc: akpm@linux-foundation.org, ktkhai@virtuozzo.com, broonie@kernel.org, hannes@cmpxchg.org, linux-mm@kvack.org, shaoyafang@didiglobal.com Subject: Re: [PATCH] mm: vmscan: add tracepoints for node reclaim Message-ID: <20190228101730.GY10588@dhcp22.suse.cz> References: <1551341664-13912-1-git-send-email-laoar.shao@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1551341664-13912-1-git-send-email-laoar.shao@gmail.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu 28-02-19 16:14:24, Yafang Shao wrote: > In the page alloc fast path, it may do node reclaim, which may cause > latency spike. > We should add tracepoint for this event, and also mesure the latency > it causes. > > So bellow two tracepoints are introduced, > mm_vmscan_node_reclaim_begin > mm_vmscan_node_reclaim_end This makes some sense to me. Regular direct reclaim already does have similar tracepoints. Is there any reason you haven't used mm_vmscan_direct_reclaim_{begin,end}_template as all other direct reclaim paths? > Signed-off-by: Yafang Shao > --- > include/trace/events/vmscan.h | 48 +++++++++++++++++++++++++++++++++++++++++++ > mm/vmscan.c | 13 +++++++++++- > 2 files changed, 60 insertions(+), 1 deletion(-) > > diff --git a/include/trace/events/vmscan.h b/include/trace/events/vmscan.h > index a1cb913..9310d5b 100644 > --- a/include/trace/events/vmscan.h > +++ b/include/trace/events/vmscan.h > @@ -465,6 +465,54 @@ > __entry->ratio, > show_reclaim_flags(__entry->reclaim_flags)) > ); > + > +TRACE_EVENT(mm_vmscan_node_reclaim_begin, > + > + TP_PROTO(int nid, int order, int may_writepage, > + gfp_t gfp_flags, int zid), > + > + TP_ARGS(nid, order, may_writepage, gfp_flags, zid), > + > + TP_STRUCT__entry( > + __field(int, nid) > + __field(int, order) > + __field(int, may_writepage) > + __field(gfp_t, gfp_flags) > + __field(int, zid) > + ), > + > + TP_fast_assign( > + __entry->nid = nid; > + __entry->order = order; > + __entry->may_writepage = may_writepage; > + __entry->gfp_flags = gfp_flags; > + __entry->zid = zid; > + ), > + > + TP_printk("nid=%d zid=%d order=%d may_writepage=%d gfp_flags=%s", > + __entry->nid, > + __entry->zid, > + __entry->order, > + __entry->may_writepage, > + show_gfp_flags(__entry->gfp_flags)) > +); > + > +TRACE_EVENT(mm_vmscan_node_reclaim_end, > + > + TP_PROTO(int result), > + > + TP_ARGS(result), > + > + TP_STRUCT__entry( > + __field(int, result) > + ), > + > + TP_fast_assign( > + __entry->result = result; > + ), > + > + TP_printk("result=%d", __entry->result) > +); > #endif /* _TRACE_VMSCAN_H */ > > /* This part must be outside protection */ > diff --git a/mm/vmscan.c b/mm/vmscan.c > index ac4806f..01a0401 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -4240,6 +4240,12 @@ static int __node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned in > .may_swap = 1, > .reclaim_idx = gfp_zone(gfp_mask), > }; > + int result; > + > + trace_mm_vmscan_node_reclaim_begin(pgdat->node_id, order, > + sc.may_writepage, > + sc.gfp_mask, > + sc.reclaim_idx); > > cond_resched(); > fs_reclaim_acquire(sc.gfp_mask); > @@ -4267,7 +4273,12 @@ static int __node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned in > current->flags &= ~PF_SWAPWRITE; > memalloc_noreclaim_restore(noreclaim_flag); > fs_reclaim_release(sc.gfp_mask); > - return sc.nr_reclaimed >= nr_pages; > + > + result = sc.nr_reclaimed >= nr_pages; > + > + trace_mm_vmscan_node_reclaim_end(result); > + > + return result; > } > > int node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned int order) > -- > 1.8.3.1 -- Michal Hocko SUSE Labs