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=-8.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, T_DKIMWL_WL_MED,URIBL_BLOCKED,USER_IN_DEF_DKIM_WL 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 B03B4C6778A for ; Tue, 3 Jul 2018 15:46:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 676752084A for ; Tue, 3 Jul 2018 15:46:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="kkhrFO7+" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 676752084A Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.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 S933168AbeGCPqn (ORCPT ); Tue, 3 Jul 2018 11:46:43 -0400 Received: from mail-wr0-f195.google.com ([209.85.128.195]:34235 "EHLO mail-wr0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932392AbeGCPqm (ORCPT ); Tue, 3 Jul 2018 11:46:42 -0400 Received: by mail-wr0-f195.google.com with SMTP id a12-v6so2483452wro.1 for ; Tue, 03 Jul 2018 08:46:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=NYtgD7zn9yg2dQjcXD0huLkS89N8S4LNFPb6cSqrwrs=; b=kkhrFO7+0ElNuSFm+gKeEOwA6RI6U8NEnpTPfKyi4ItyFDOnp1wGwVPXLCOWxvtU1w LP/YGqqko+ZD1vH6+gDsEcXYNPRVJ2j9d7tvXOOpRjqtV+jxQr+b+xyJx2BazBhUZhjR 34EAL4XlgkJ0v5/AmihMynDou50ds+0Y6RtREEyFZSTCareGO0vyTW7h20hDCLbWy6K7 Q7+OCLM0hNMKhn3Rc1e0wQhOjex4SJXPNOu9w3ZZiFrsHK2oQJihT24FkHlzgk+DHuGE kUfgdqxF9sMP9fO5C6AnjS5qxum5M3IlB7/QxIl4971KbiHiA4/5O8E+PF2pxNrMEeC5 dN9Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=NYtgD7zn9yg2dQjcXD0huLkS89N8S4LNFPb6cSqrwrs=; b=VajFsQG9p1h4U36EQKQjP4Dgi+CgqQntUaE2x0et1NVLO9caJEINROI/mKUYjj0X4F PUmPT8kk5NlhJxDsVF4SJ5Vdv9+SyLHFFy4V9Wqc+QSJTiK0CmTpmnQeJfMPoCRZlseZ vWCxtp+vmJXHDQamnNhtooJZpIKi4DBTeSHXUYRXoDE6c2MB8KOldvIg8UTVlNjIoFG6 5jzBpXCyW2sNU3uF7AMhDRCcp5NItVk8x/PQDYXMUpg6xC80y23ulxUmBup67I9wlVI+ vrKsF/jeIGfRijNJvuf8Swd9keocikKIyHEgY/d/u4OA6TzcuUB5ZurMT5FLZCt7CFjY fyOA== X-Gm-Message-State: APt69E2255lvyv7kOATQlYAaO4iQT1r1VyF0bWNr2szk6eS5t3XQKuv+ SROPxq7QS2GKcf/HFbmx10TLBlMe1SDItb447J2sFA== X-Google-Smtp-Source: AAOMgpcW1qus/WFrDYBRbKrJKILpupUfUHWNMIKFj8/UTed/7I6b3dJmiQjskvcS7L5+FKplra0cY8ajP5Fmkj8t2jk= X-Received: by 2002:adf:b3d4:: with SMTP id x20-v6mr23572404wrd.272.1530632800511; Tue, 03 Jul 2018 08:46:40 -0700 (PDT) MIME-Version: 1.0 References: <153063036670.1818.16010062622751502.stgit@localhost.localdomain> <153063054586.1818.6041047871606697364.stgit@localhost.localdomain> <20180703152723.GB21590@bombadil.infradead.org> In-Reply-To: <20180703152723.GB21590@bombadil.infradead.org> From: Shakeel Butt Date: Tue, 3 Jul 2018 08:46:28 -0700 Message-ID: Subject: Re: [PATCH v8 03/17] mm: Assign id to every memcg-aware shrinker To: Matthew Wilcox Cc: Kirill Tkhai , Vladimir Davydov , Alexander Viro , Johannes Weiner , Michal Hocko , Thomas Gleixner , Philippe Ombredanne , stummala@codeaurora.org, gregkh@linuxfoundation.org, Stephen Rothwell , Roman Gushchin , mka@chromium.org, Tetsuo Handa , Chris Wilson , longman@redhat.com, Minchan Kim , Huang Ying , Mel Gorman , jbacik@fb.com, Guenter Roeck , LKML , Linux MM , lirongqing@baidu.com, Andrey Ryabinin , Andrew Morton Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 3, 2018 at 8:27 AM Matthew Wilcox wrote: > > On Tue, Jul 03, 2018 at 06:09:05PM +0300, Kirill Tkhai wrote: > > +++ b/mm/vmscan.c > > @@ -169,6 +169,49 @@ unsigned long vm_total_pages; > > static LIST_HEAD(shrinker_list); > > static DECLARE_RWSEM(shrinker_rwsem); > > > > +#ifdef CONFIG_MEMCG_KMEM > > +static DEFINE_IDR(shrinker_idr); > > +static int shrinker_nr_max; > > So ... we've now got a list_head (shrinker_list) which contains all of > the shrinkers, plus a shrinker_idr which contains the memcg-aware shrinkers? > > Why not replace the shrinker_list with the shrinker_idr? It's only used > twice in vmscan.c: > > void register_shrinker_prepared(struct shrinker *shrinker) > { > down_write(&shrinker_rwsem); > list_add_tail(&shrinker->list, &shrinker_list); > up_write(&shrinker_rwsem); > } > > list_for_each_entry(shrinker, &shrinker_list, list) { > ... > > The first is simply idr_alloc() and the second is > > idr_for_each_entry(&shrinker_idr, shrinker, id) { > > I understand there's a difference between allocating the shrinker's ID and > adding it to the list. You can do this by calling idr_alloc with NULL > as the pointer, and then using idr_replace() when you want to add the > shrinker to the list. idr_for_each_entry() skips over NULL entries. > > This will actually reduce the size of each shrinker and be more > cache-efficient when calling the shrinkers. I think we can also get > rid of the shrinker_rwsem eventually, but let's leave it for now. Can you explain how you envision shrinker_rwsem can be removed? I am very much interested in doing that. thanks, Shakeel