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=-3.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 9419EC47254 for ; Tue, 5 May 2020 15:47:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 74C4F2078C for ; Tue, 5 May 2020 15:47:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b="G+Q7z7KL" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730421AbgEEPr1 (ORCPT ); Tue, 5 May 2020 11:47:27 -0400 Received: from smtp-fw-9101.amazon.com ([207.171.184.25]:63427 "EHLO smtp-fw-9101.amazon.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729406AbgEEPr1 (ORCPT ); Tue, 5 May 2020 11:47:27 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1588693647; x=1620229647; h=from:to:cc:subject:date:message-id:in-reply-to: mime-version; bh=qgL+UrIHPggA/cbMIcuZ6L6wlHkLvvYMOzgo5iwxhgg=; b=G+Q7z7KLHWVXnfTXL6vCm+I433aihc4qv6kJ4WtoMTKroRNfPk1h2ODX OF6z/eK/BT306TyXHZLwicMXlh1LxUV8H66LNNDTsbf9ehFMfjnYhlQjE jI8MAGvELZ+s45fCv7TLThd3hP0hjX2NmaUVQsLs2nttVoml0/fnqvhKa U=; IronPort-SDR: O166hFl/kUUCS2stThOFXVSw6unJMOC3/77W9R3kUjp/BSPJ10ib3NA17O1H6Lb1AtOuv/GJ+Y 1lR6gvyLhizA== X-IronPort-AV: E=Sophos;i="5.73,355,1583193600"; d="scan'208";a="33074496" Received: from sea32-co-svc-lb4-vlan3.sea.corp.amazon.com (HELO email-inbound-relay-1d-5dd976cd.us-east-1.amazon.com) ([10.47.23.38]) by smtp-border-fw-out-9101.sea19.amazon.com with ESMTP; 05 May 2020 15:47:24 +0000 Received: from EX13MTAUEA002.ant.amazon.com (iad55-ws-svc-p15-lb9-vlan3.iad.amazon.com [10.40.159.166]) by email-inbound-relay-1d-5dd976cd.us-east-1.amazon.com (Postfix) with ESMTPS id DA09DA225F; Tue, 5 May 2020 15:47:20 +0000 (UTC) Received: from EX13D31EUA001.ant.amazon.com (10.43.165.15) by EX13MTAUEA002.ant.amazon.com (10.43.61.77) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Tue, 5 May 2020 15:47:20 +0000 Received: from u886c93fd17d25d.ant.amazon.com (10.43.162.38) by EX13D31EUA001.ant.amazon.com (10.43.165.15) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Tue, 5 May 2020 15:47:12 +0000 From: SeongJae Park To: Eric Dumazet CC: SeongJae Park , Eric Dumazet , David Miller , Al Viro , "Jakub Kicinski" , Greg Kroah-Hartman , , netdev , LKML , SeongJae Park , , , Subject: Re: Re: [PATCH net v2 0/2] Revert the 'socket_alloc' life cycle change Date: Tue, 5 May 2020 17:46:44 +0200 Message-ID: <20200505154644.18997-1-sjpark@amazon.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: (raw) MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.43.162.38] X-ClientProxiedBy: EX13D18UWC003.ant.amazon.com (10.43.162.237) To EX13D31EUA001.ant.amazon.com (10.43.165.15) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Tue, 5 May 2020 08:20:50 -0700 Eric Dumazet wrote: > > > On 5/5/20 8:07 AM, SeongJae Park wrote: > > On Tue, 5 May 2020 07:53:39 -0700 Eric Dumazet wrote: > > > > >> Why do we have 10,000,000 objects around ? Could this be because of > >> some RCU problem ? > > > > Mainly because of a long RCU grace period, as you guess. I have no idea how > > the grace period became so long in this case. > > > > As my test machine was a virtual machine instance, I guess RCU readers > > preemption[1] like problem might affected this. > > > > [1] https://www.usenix.org/system/files/conference/atc17/atc17-prasad.pdf > > > >> > >> Once Al patches reverted, do you have 10,000,000 sock_alloc around ? > > > > Yes, both the old kernel that prior to Al's patches and the recent kernel > > reverting the Al's patches didn't reproduce the problem. > > > > I repeat my question : Do you have 10,000,000 (smaller) objects kept in slab caches ? > > TCP sockets use the (very complex, error prone) SLAB_TYPESAFE_BY_RCU, but not the struct socket_wq > object that was allocated in sock_alloc_inode() before Al patches. > > These objects should be visible in kmalloc-64 kmem cache. Not exactly the 10,000,000, as it is only the possible highest number, but I was able to observe clear exponential increase of the number of the objects using slabtop. Before the start of the problematic workload, the number of objects of 'kmalloc-64' was 5760, but I was able to observe the number increase to 1,136,576. OBJS ACTIVE USE OBJ SIZE SLABS OBJ/SLAB CACHE SIZE NAME before: 5760 5088 88% 0.06K 90 64 360K kmalloc-64 after: 1136576 1136576 100% 0.06K 17759 64 71036K kmalloc-64 Thanks, SeongJae Park