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=-7.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 E4D26C433EF for ; Mon, 20 Sep 2021 14:12:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C7EB26112D for ; Mon, 20 Sep 2021 14:12:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234594AbhITONe (ORCPT ); Mon, 20 Sep 2021 10:13:34 -0400 Received: from smtp-out1.suse.de ([195.135.220.28]:57632 "EHLO smtp-out1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230175AbhITONb (ORCPT ); Mon, 20 Sep 2021 10:13:31 -0400 Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out1.suse.de (Postfix) with ESMTP id 3E77F21E7C; Mon, 20 Sep 2021 14:12:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1632147124; h=from:from:reply-to:reply-to:date:date:message-id:message-id:to:to: cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=7YZycW7OK1xqPCqQ0PYTJxyKG0/lg8miVizE0TtV33s=; b=nFG8Lwf9RHij/Hz5MLtk5b2dhULRS3DnSnRo6B0ABmwFh8POog9oEpE0zaXjtlL6i0UyLx DaV4jhCTh8Yk6X/A6TZaX0xiClYI2COB5CEmCn1J7kA+3YgaDzJDAkZvjpY1Xb/V6s0BAG beN+uvXFsT+aSVCTvAJQH6QrkwiDzqw= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1632147124; h=from:from:reply-to:reply-to:date:date:message-id:message-id:to:to: cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=7YZycW7OK1xqPCqQ0PYTJxyKG0/lg8miVizE0TtV33s=; b=GXP2WHPbdYhcobfrUQXqE+v5htzJez2gLQ3UhwsIfmeeqW5/8NXg/+DBVe7PjIkQbFUNDw q4/Kp17W/Iw8r9CQ== Received: from ds.suse.cz (ds.suse.cz [10.100.12.205]) by relay2.suse.de (Postfix) with ESMTP id D161DA3B96; Mon, 20 Sep 2021 14:12:03 +0000 (UTC) Received: by ds.suse.cz (Postfix, from userid 10065) id 3E029DA7FB; Mon, 20 Sep 2021 16:11:52 +0200 (CEST) Date: Mon, 20 Sep 2021 16:11:52 +0200 From: David Sterba To: Mel Gorman Cc: Matthew Wilcox , Linux-MM , NeilBrown , Theodore Ts'o , Andreas Dilger , "Darrick J . Wong" , Michal Hocko , Dave Chinner , Rik van Riel , Vlastimil Babka , Johannes Weiner , Jonathan Corbet , Linux-fsdevel , LKML Subject: Re: [RFC PATCH 0/5] Remove dependency on congestion_wait in mm/ Message-ID: <20210920141152.GM9286@twin.jikos.cz> Reply-To: dsterba@suse.cz Mail-Followup-To: dsterba@suse.cz, Mel Gorman , Matthew Wilcox , Linux-MM , NeilBrown , Theodore Ts'o , Andreas Dilger , "Darrick J . Wong" , Michal Hocko , Dave Chinner , Rik van Riel , Vlastimil Babka , Johannes Weiner , Jonathan Corbet , Linux-fsdevel , LKML References: <20210920085436.20939-1-mgorman@techsingularity.net> <20210920125058.GI3959@techsingularity.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210920125058.GI3959@techsingularity.net> User-Agent: Mutt/1.5.23.1-rc1 (2014-03-12) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Sep 20, 2021 at 01:50:58PM +0100, Mel Gorman wrote: > On Mon, Sep 20, 2021 at 12:42:44PM +0100, Matthew Wilcox wrote: > > On Mon, Sep 20, 2021 at 09:54:31AM +0100, Mel Gorman wrote: > > > This has been lightly tested only and the testing was useless as the > > > relevant code was not executed. The workload configurations I had that > > > used to trigger these corner cases no longer work (yey?) and I'll need > > > to implement a new synthetic workload. If someone is aware of a realistic > > > workload that forces reclaim activity to the point where reclaim stalls > > > then kindly share the details. > > > > The stereeotypical "stalling on I/O" problem is to plug in one of the > > crap USB drives you were given at a trade show and simply > > dd if=/dev/zero of=/dev/sdb > > sync > > > > The test machines are 1500KM away so plugging in a USB stick but worst > comes to the worst, I could test it on a laptop. There's a device mapper target dm-delay [1] that as it says delays the reads and writes, so you could try to emulate the slow USB that way. [1] https://www.kernel.org/doc/html/latest/admin-guide/device-mapper/delay.html