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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D5DCCC10DC1 for ; Mon, 4 Dec 2023 18:16:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231965AbjLDSPz (ORCPT ); Mon, 4 Dec 2023 13:15:55 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60594 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231783AbjLDSPx (ORCPT ); Mon, 4 Dec 2023 13:15:53 -0500 Received: from out-183.mta1.migadu.com (out-183.mta1.migadu.com [95.215.58.183]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B3E0BCA for ; Mon, 4 Dec 2023 10:15:58 -0800 (PST) Date: Mon, 4 Dec 2023 13:15:53 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1701713756; 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: in-reply-to:in-reply-to:references:references; bh=xC4jCVvT+IFQ6qX/7Rd+v3ZG1sbqYN9jp27m45RKW54=; b=UInPrONmCV4wOdcNrtM+3QKuViLTgz3GTf2O+imE34q5jZJZWmag47hsLh1rGFQh7N2A06 qITVIBE9zgAidF9KNEnWUrz6bRgzRRoe3BTqo51XOnC76bY3uIRfgfkCLdOdLu2FtAAIVG r8ZFMCosxb6H6BFvH3WEvhQCnFDR3MI= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Kent Overstreet To: Michal Hocko Cc: Roman Gushchin , Qi Zheng , Muchun Song , Linux-MM , linux-kernel@vger.kernel.org, Andrew Morton , Dave Chinner Subject: Re: [PATCH 2/7] mm: shrinker: Add a .to_text() method for shrinkers Message-ID: <20231204181553.tyxeq7zy54cuc3o7@moria.home.lan> References: <20231128035345.5c7yc7jnautjpfoc@moria.home.lan> <20231129231147.7msiocerq7phxnyu@moria.home.lan> <20231201014745.b2ud4w3ymztdtctu@moria.home.lan> <20231201212506.skgzaoafi5zgi3pi@moria.home.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Dec 04, 2023 at 11:33:12AM +0100, Michal Hocko wrote: > On Fri 01-12-23 16:25:06, Kent Overstreet wrote: > > On Fri, Dec 01, 2023 at 11:04:23AM +0100, Michal Hocko wrote: > > > On Thu 30-11-23 20:47:45, Kent Overstreet wrote: > > > > On Thu, Nov 30, 2023 at 09:14:35AM +0100, Michal Hocko wrote: > > > [...] > > > > > All that being said, I am with you on the fact that the oom report in > > > > > its current form could see improvements. > > > > > > > > I'm glad we're finally in agreement on something! > > > > > > > > If you want to share your own ideas on what could be improved and what > > > > you find useful, maybe we could find some more common ground. > > > > > > One thing that I would consider an improvement is to have a way to > > > subscribe drivers with excessive memory consumption or those which are > > > struggling to dump their state. > > > > Remember the memory allocation profiling patchset? The one where you > > kept complaining about "maintenancy overhead"? > > Yes, I still maintain my opinion on that approach. I have never > questioned usefulness of the information. > > > We can plug that into the show_mem report too, and list the top 10 > > allocations by file and line number. > > > > > Maybe your proposal can be extended that way but the crucial point is to > > > not dump all sorts of random shrinkers' state and end up with unwieldy > > > reports. If, on the other hand, any particular shrinker struggles to > > > reclaim memory and it is sitting on a lot of memory it could be able to > > > flag itself to be involved in the dump. > > > > Great, since as was mentioned in the original commit message it's not > > "all sorts of random shrinkers", but top 10 by objects reported, what > > I've got here should make you happy. > > Can we do better and make that a shrinker decision rather than an > arbitrary top N selection? The thing is that shrinkers might even not > matter in many cases so their output would be just a balast. The number > of objects is not universaly great choice. As Dave mentioned metdata > might be pinning other objects. > > That being said, if you want to give more debugability power to > shrinkers then it makes more sense to allow them to opt-in for the oom > report rather than control which of them to involve from the oom > reporting code which doesn't have enough context on its own. If you've got an idea for a refinement, please submit your own patch and I'll look at incorporating it into the series.