From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753452AbbFIO2H (ORCPT ); Tue, 9 Jun 2015 10:28:07 -0400 Received: from mx1.redhat.com ([209.132.183.28]:49894 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751649AbbFIO2C (ORCPT ); Tue, 9 Jun 2015 10:28:02 -0400 From: Jeff Moyer To: Tejun Heo Cc: axboe@kernel.dk, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, vgoyal@redhat.com, avanzini.arianna@gmail.com Subject: Re: [PATCH 4.5/8] blkcg, cfq-iosched: use GFP_NOWAIT instead of GFP_ATOMIC for non-critical allocations References: <1433753973-23684-1-git-send-email-tj@kernel.org> <20150609042131.GN21465@mtj.duckdns.org> X-PGP-KeyID: 1F78E1B4 X-PGP-CertKey: F6FE 280D 8293 F72C 65FD 5A58 1FF8 A7CA 1F78 E1B4 X-PCLoadLetter: What the f**k does that mean? Date: Tue, 09 Jun 2015 10:27:59 -0400 In-Reply-To: <20150609042131.GN21465@mtj.duckdns.org> (Tejun Heo's message of "Tue, 9 Jun 2015 13:21:31 +0900") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Tejun Heo writes: > From b848495d2c987e960d1f7794966d82c05fcefc6d Mon Sep 17 00:00:00 2001 > From: Tejun Heo > Date: Tue, 9 Jun 2015 13:19:40 +0900 > > blkcg performs several allocations to track IOs per cgroup and enforce > resource control. Most of these allocations are performed lazily on > demand in the IO path and thus can't involve reclaim path. Currently, > these allocations use GFP_ATOMIC; however, blkcg can gracefully deal > with occassional failures of these allocations by punting IOs to the > root cgroup and there's no reason to reach into the emergency reserve. > > This patch replaces GFP_ATOMIC with GFP_NOWAIT for the following > allocations. > > * bdi_writeback_congested and blkcg_gq allocations in blkg_create(). > > * radix tree node allocations for blkcg->blkg_tree. > > * cfq_queue allocation on ioprio changes. > > Signed-off-by: Tejun Heo > Suggested-by: Jeff Moyer > Suggested-by: Vivek Goyal Thanks, Tejun! Reviewed-by: Jeff Moyer