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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 2E44CC4321D for ; Wed, 22 Aug 2018 13:03:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C9D9820C0F for ; Wed, 22 Aug 2018 13:03:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C9D9820C0F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=applied-asynchrony.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728665AbeHVQ1w (ORCPT ); Wed, 22 Aug 2018 12:27:52 -0400 Received: from mail02.iobjects.de ([188.40.134.68]:33432 "EHLO mail02.iobjects.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728012AbeHVQ1v (ORCPT ); Wed, 22 Aug 2018 12:27:51 -0400 X-Greylist: delayed 526 seconds by postgrey-1.27 at vger.kernel.org; Wed, 22 Aug 2018 12:27:50 EDT Received: from tux.wizards.de (p3EE2F932.dip0.t-ipconnect.de [62.226.249.50]) by mail02.iobjects.de (Postfix) with ESMTPSA id 0461941678B7; Wed, 22 Aug 2018 14:54:16 +0200 (CEST) Received: from [192.168.100.223] (ragnarok.applied-asynchrony.com [192.168.100.223]) by tux.wizards.de (Postfix) with ESMTP id 8831FF015F9; Wed, 22 Aug 2018 14:54:15 +0200 (CEST) Subject: Re: [PATCH] blk-wbt: Avoid lock contention and thundering herd issue in wbt_wait To: Jens Axboe , Anchal Agarwal Cc: fllinden@amazon.com, sblbir@amazon.com, msw@amazon.com, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org References: <6bab69c9-b787-b12f-7738-72e05bf74444@kernel.dk> <72f90be2-0b63-d3a0-e953-da9232f44d5b@kernel.dk> <761bb0ab416649b8bf3bac1706124456@EX13D13UWB002.ant.amazon.com> <7f6c399d-bda1-0bbf-4ea1-07fc510ed1eb@kernel.dk> <3498fbfb-e9f3-7606-1fc3-904a0e61ff57@kernel.dk> <168d80ac73a44a6f9242c47c164778fc@EX13D13UWB002.ant.amazon.com> <20180820224241.GA72523@8c8590bceeee.ant.amazon.com> <70e2063a-53fa-2475-eed9-07db277c8c0d@kernel.dk> <20180822040126.GA18736@kaos-source-ops-60001.pdx1.amazon.com> <76ecb022-f167-67eb-8801-111fc209bbaa@kernel.dk> From: =?UTF-8?Q?Holger_Hoffst=c3=a4tte?= Organization: Applied Asynchrony, Inc. Message-ID: <834649ab-62d6-bc7f-ec60-6c1654ea3f26@applied-asynchrony.com> Date: Wed, 22 Aug 2018 14:54:15 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <76ecb022-f167-67eb-8801-111fc209bbaa@kernel.dk> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/22/18 06:10, Jens Axboe wrote: > [...] > If you have time, please look at the 3 patches I posted earlier today. > Those are for mainline, so should be OK :-) I'm just playing along at home but with those 3 I get repeatable hangs & writeback not starting at all, but curiously *only* on my btrfs device; for inexplicable reasons some other devices with ext4/xfs flush properly. Yes, that surprised me too, but it's repeatable. Now this may or may not have something to do with some of my in-testing patches for btrfs itself, but if I remove those 3 wbt fixes, everything is golden again. Not eager to repeat since it hangs sync & requires a hard reboot.. :( Just thought you'd like to know. -h