From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3A4CFCA9EB6 for ; Wed, 23 Oct 2019 13:46:38 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id E52CF20663 for ; Wed, 23 Oct 2019 13:46:37 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="dRUBgccV" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E52CF20663 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 9904B6B0005; Wed, 23 Oct 2019 09:46:37 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 940DC6B0006; Wed, 23 Oct 2019 09:46:37 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 87DAE6B0007; Wed, 23 Oct 2019 09:46:37 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0020.hostedemail.com [216.40.44.20]) by kanga.kvack.org (Postfix) with ESMTP id 648C66B0005 for ; Wed, 23 Oct 2019 09:46:37 -0400 (EDT) Received: from smtpin14.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with SMTP id F302481D1 for ; Wed, 23 Oct 2019 13:46:36 +0000 (UTC) X-FDA: 76075174392.14.hate90_39b7361c0cb23 X-HE-Tag: hate90_39b7361c0cb23 X-Filterd-Recvd-Size: 5772 Received: from us-smtp-1.mimecast.com (us-smtp-delivery-1.mimecast.com [205.139.110.120]) by imf02.hostedemail.com (Postfix) with ESMTP for ; Wed, 23 Oct 2019 13:46:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1571838396; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=580cpyTZn31Tsw5lMtWLo7PXKcx4eNMbv5larOIYwnY=; b=dRUBgccVcuJCmFQ8WF4IqNlYta0SpjjDTABJu3i4ug77Iux62v8IKs5wQX2FQJh7lWMHSv cigKnyS2jdzVDVLkWFPGc3MB2SYiNYVCk6zOjI4G1xs8+Oyr+1xzl9IiX/Y18A92zyaDYN sa9AcneI/MI8Aaspm13rI05Z/tEVUJ0= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-378-HjTE_xT0PXuakUoiGj67-g-1; Wed, 23 Oct 2019 09:46:34 -0400 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 2DF81800D49; Wed, 23 Oct 2019 13:46:32 +0000 (UTC) Received: from optiplex-lnx (ovpn-112-50.rdu2.redhat.com [10.10.112.50]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 245C319C77; Wed, 23 Oct 2019 13:46:24 +0000 (UTC) Date: Wed, 23 Oct 2019 09:46:22 -0400 From: Rafael Aquini To: Vlastimil Babka Cc: Michal Hocko , Andrew Morton , Mel Gorman , Waiman Long , Johannes Weiner , Roman Gushchin , Konstantin Khlebnikov , Jann Horn , Song Liu , Greg Kroah-Hartman , linux-mm@kvack.org, LKML , Michal Hocko Subject: Re: [RFC PATCH 2/2] mm, vmstat: reduce zone->lock holding time by /proc/pagetypeinfo Message-ID: <20191023134622.GA22601@optiplex-lnx> References: <20191023095607.GE3016@techsingularity.net> <20191023102737.32274-1-mhocko@kernel.org> <20191023102737.32274-3-mhocko@kernel.org> <30211965-8ad0-416d-0fe1-113270bd1ea8@suse.cz> MIME-Version: 1.0 In-Reply-To: <30211965-8ad0-416d-0fe1-113270bd1ea8@suse.cz> User-Agent: Mutt/1.12.1 (2019-06-15) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-MC-Unique: HjTE_xT0PXuakUoiGj67-g-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline 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 Wed, Oct 23, 2019 at 03:32:05PM +0200, Vlastimil Babka wrote: > On 10/23/19 12:27 PM, Michal Hocko wrote: > > From: Michal Hocko > >=20 > > pagetypeinfo_showfree_print is called by zone->lock held in irq mode. > > This is not really nice because it blocks both any interrupts on that > > cpu and the page allocator. On large machines this might even trigger > > the hard lockup detector. > >=20 > > Considering the pagetypeinfo is a debugging tool we do not really need > > exact numbers here. The primary reason to look at the outuput is to see > > how pageblocks are spread among different migratetypes therefore puttin= g > > a bound on the number of pages on the free_list sounds like a reasonabl= e > > tradeoff. > >=20 > > The new output will simply tell > > [...] > > Node 6, zone Normal, type Movable >100000 >100000 >100000 >10= 0000 41019 31560 23996 10054 3229 983 648 > >=20 > > instead of > > Node 6, zone Normal, type Movable 399568 294127 221558 102119= 41019 31560 23996 10054 3229 983 648 > >=20 > > The limit has been chosen arbitrary and it is a subject of a future > > change should there be a need for that. > >=20 > > Suggested-by: Andrew Morton > > Signed-off-by: Michal Hocko >=20 > Hmm dunno, I would rather e.g. hide the file behind some config or boot > option than do this. Or move it to /sys/kernel/debug ? > You beat me to it. I was going to suggest moving it to debug, as well. =20 > > --- > > mm/vmstat.c | 19 ++++++++++++++++++- > > 1 file changed, 18 insertions(+), 1 deletion(-) > >=20 > > diff --git a/mm/vmstat.c b/mm/vmstat.c > > index 4e885ecd44d1..762034fc3b83 100644 > > --- a/mm/vmstat.c > > +++ b/mm/vmstat.c > > @@ -1386,8 +1386,25 @@ static void pagetypeinfo_showfree_print(struct s= eq_file *m, > > =20 > > =09=09=09area =3D &(zone->free_area[order]); > > =20 > > -=09=09=09list_for_each(curr, &area->free_list[mtype]) > > +=09=09=09list_for_each(curr, &area->free_list[mtype]) { > > =09=09=09=09freecount++; > > +=09=09=09=09/* > > +=09=09=09=09 * Cap the free_list iteration because it might > > +=09=09=09=09 * be really large and we are under a spinlock > > +=09=09=09=09 * so a long time spent here could trigger a > > +=09=09=09=09 * hard lockup detector. Anyway this is a > > +=09=09=09=09 * debugging tool so knowing there is a handful > > +=09=09=09=09 * of pages in this order should be more than > > +=09=09=09=09 * sufficient > > +=09=09=09=09 */ > > +=09=09=09=09if (freecount > 100000) { > > +=09=09=09=09=09seq_printf(m, ">%6lu ", freecount); > > +=09=09=09=09=09spin_unlock_irq(&zone->lock); > > +=09=09=09=09=09cond_resched(); > > +=09=09=09=09=09spin_lock_irq(&zone->lock); > > +=09=09=09=09=09continue; > > +=09=09=09=09} > > +=09=09=09} > > =09=09=09seq_printf(m, "%6lu ", freecount); > > =09=09} > > =09=09seq_putc(m, '\n'); > >=20 >=20