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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 92E16C433F5 for ; Wed, 27 Apr 2022 15:22:25 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id C60F86B0072; Wed, 27 Apr 2022 11:22:24 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id C10096B0073; Wed, 27 Apr 2022 11:22:24 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id AD8216B0074; Wed, 27 Apr 2022 11:22:24 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.hostedemail.com [64.99.140.25]) by kanga.kvack.org (Postfix) with ESMTP id A00086B0072 for ; Wed, 27 Apr 2022 11:22:24 -0400 (EDT) Received: from smtpin14.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 6F689289CF for ; Wed, 27 Apr 2022 15:22:24 +0000 (UTC) X-FDA: 79403025408.14.5423841 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by imf03.hostedemail.com (Postfix) with ESMTP id 565E02004B for ; Wed, 27 Apr 2022 15:22:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1651072943; 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=LNAyzMhGrm56//UE4/ZGodPQJ3CS7zahQHt/zd8A0Jg=; b=eP05sX7y9cbxKQwLtx0MaCatkOW90kEWkj8dCRNYn0fjYYOnH4elppW64hvbYewr5fGkoS 0J70YIPt/p/UiAweOqEEm3yq3bKbm/6+HFHhT6/Y8rPqeLKhGJCvD1A443VEAxgf7x1f63 L+yS9YTh40oHQqpsl+PSMZsx1TRXSTQ= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-245-N_FnrifQOxWIGho6WLXR_g-1; Wed, 27 Apr 2022 11:22:19 -0400 X-MC-Unique: N_FnrifQOxWIGho6WLXR_g-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 6C24280418C; Wed, 27 Apr 2022 15:22:19 +0000 (UTC) Received: from fuller.cnet (ovpn-112-2.gru2.redhat.com [10.97.112.2]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 1B5A21468F21; Wed, 27 Apr 2022 15:22:19 +0000 (UTC) Received: by fuller.cnet (Postfix, from userid 1000) id E7726416F574; Wed, 27 Apr 2022 12:21:47 -0300 (-03) Date: Wed, 27 Apr 2022 12:21:47 -0300 From: Marcelo Tosatti To: Nicolas Saenz Julienne Cc: Minchan Kim , Mel Gorman , Vlastimil Babka , Michal Hocko , LKML , Linux-MM Subject: Re: [RFC PATCH 0/6] Drain remote per-cpu directly Message-ID: References: <20220420095906.27349-1-mgorman@techsingularity.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Scanned-By: MIMEDefang 2.85 on 10.11.54.7 X-Rspamd-Queue-Id: 565E02004B X-Stat-Signature: ewsjf58xsz7m34ut54w95mimnrkf8mmo Authentication-Results: imf03.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=eP05sX7y; dmarc=pass (policy=none) header.from=redhat.com; spf=none (imf03.hostedemail.com: domain of mtosatti@redhat.com has no SPF policy when checking 170.10.129.124) smtp.mailfrom=mtosatti@redhat.com X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1651072940-928872 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 Tue, Apr 26, 2022 at 01:06:12PM +0200, Nicolas Saenz Julienne wrote: > On Mon, 2022-04-25 at 15:58 -0700, Minchan Kim wrote: > > On Wed, Apr 20, 2022 at 10:59:00AM +0100, Mel Gorman wrote: > > > This series has the same intent as Nicolas' series "mm/page_alloc: Remote > > > per-cpu lists drain support" -- avoid interference of a high priority > > > task due to a workqueue item draining per-cpu page lists. While many > > > workloads can tolerate a brief interruption, it may be cause a real-time > > > task runnning on a NOHZ_FULL CPU to miss a deadline and at minimum, > > > the draining in non-deterministic. > > > > Yeah, the non-deterministic is a problem. I saw the kworker-based draining > > takes 100+ms(up to 300ms observed) sometimes in alloc_contig_range if CPUs > > are heavily loaded. > > > > I am not sure Nicolas already observed. it's not only problem of > > per_cpu_pages but it is also lru_pvecs (pagevec) draining. > > Do we need to introduce similar(allow remote drainning with spin_lock) > > solution for pagevec? > > Yes, I'm aware of the lru problem. I'll start working on it too once we're done > with the page allocator (and if no-one beats me to it). That said, I don't know > if we can apply the exact same approach, the devil is in the details. :) I think one necessary step for that (adding spinlock to protect per-CPU lru_pvecs) would be to find a suitable testcase. Mel, do you have anything in mind ? > > -- > Nicolás Sáenz > >