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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 B3CC6C43603 for ; Wed, 3 Mar 2021 19:28:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 80D9664ED0 for ; Wed, 3 Mar 2021 19:28:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1579608AbhCCSbk (ORCPT ); Wed, 3 Mar 2021 13:31:40 -0500 Received: from mga18.intel.com ([134.134.136.126]:38123 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237191AbhCCQcg (ORCPT ); Wed, 3 Mar 2021 11:32:36 -0500 IronPort-SDR: Tu6Ha1ASxdEbpU8QwFuSFx2LJJO3vXyeBZU+fWvsYHWnwzlSQRJQ+rz0naQBcVph8Q+ZDJG0Ew Vcvk81uI/zOA== X-IronPort-AV: E=McAfee;i="6000,8403,9912"; a="174868592" X-IronPort-AV: E=Sophos;i="5.81,220,1610438400"; d="scan'208";a="174868592" Received: from orsmga006.jf.intel.com ([10.7.209.51]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Mar 2021 08:31:43 -0800 IronPort-SDR: J1UeOUl5u6xfU8M0uMOUSh4yNCzAjMWgs2o/esffwgKbM8LsqKZwkguO6s1cM/rWwsm1BqPQj3 TOsq5mfKhLTA== X-IronPort-AV: E=Sophos;i="5.81,220,1610438400"; d="scan'208";a="369442522" Received: from tsaijane-mobl.amr.corp.intel.com (HELO intel.com) ([10.252.136.84]) by orsmga006-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Mar 2021 08:31:42 -0800 Date: Wed, 3 Mar 2021 08:31:41 -0800 From: Ben Widawsky To: Michal Hocko Cc: Feng Tang , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , Andrew Morton , Andrea Arcangeli , David Rientjes , Mel Gorman , Mike Kravetz , Randy Dunlap , Vlastimil Babka , "Hansen, Dave" , Andi leen , "Williams, Dan J" Subject: Re: [PATCH v3 RFC 14/14] mm: speedup page alloc for MPOL_PREFERRED_MANY by adding a NO_SLOWPATH gfp bit Message-ID: <20210303163141.v5wu2sfo2zj2qqsw@intel.com> Mail-Followup-To: Michal Hocko , Feng Tang , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , Andrew Morton , Andrea Arcangeli , David Rientjes , Mel Gorman , Mike Kravetz , Randy Dunlap , Vlastimil Babka , "Hansen, Dave" , Andi leen , "Williams, Dan J" References: <1614766858-90344-1-git-send-email-feng.tang@intel.com> <1614766858-90344-15-git-send-email-feng.tang@intel.com> <20210303120717.GA16736@shbuild999.sh.intel.com> <20210303121833.GB16736@shbuild999.sh.intel.com> <20210303131832.GB78458@shbuild999.sh.intel.com> <20210303134644.GC78458@shbuild999.sh.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 21-03-03 14:59:35, Michal Hocko wrote: > On Wed 03-03-21 21:46:44, Feng Tang wrote: > > On Wed, Mar 03, 2021 at 09:18:32PM +0800, Tang, Feng wrote: > > > On Wed, Mar 03, 2021 at 01:32:11PM +0100, Michal Hocko wrote: > > > > On Wed 03-03-21 20:18:33, Feng Tang wrote: > [...] > > > > > One thing I tried which can fix the slowness is: > > > > > > > > > > + gfp_mask &= ~(__GFP_DIRECT_RECLAIM | __GFP_KSWAPD_RECLAIM); > > > > > > > > > > which explicitly clears the 2 kinds of reclaim. And I thought it's too > > > > > hacky and didn't mention it in the commit log. > > > > > > > > Clearing __GFP_DIRECT_RECLAIM would be the right way to achieve > > > > GFP_NOWAIT semantic. Why would you want to exclude kswapd as well? > > > > > > When I tried gfp_mask &= ~__GFP_DIRECT_RECLAIM, the slowness couldn't > > > be fixed. > > > > I just double checked by rerun the test, 'gfp_mask &= ~__GFP_DIRECT_RECLAIM' > > can also accelerate the allocation much! though is still a little slower than > > this patch. Seems I've messed some of the tries, and sorry for the confusion! > > > > Could this be used as the solution? or the adding another fallback_nodemask way? > > but the latter will change the current API quite a bit. > > I haven't got to the whole series yet. The real question is whether the > first attempt to enforce the preferred mask is a general win. I would > argue that it resembles the existing single node preferred memory policy > because that one doesn't push heavily on the preferred node either. So > dropping just the direct reclaim mode makes some sense to me. > > IIRC this is something I was recommending in an early proposal of the > feature. My assumption [FWIW] is that the usecases we've outlined for multi-preferred would want more heavy pushing on the preference mask. However, maybe the uapi could dictate how hard to try/not try.