From patchwork Fri Dec 14 21:53:01 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Waiman Long X-Patchwork-Id: 10731701 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 41B0C13BF for ; Fri, 14 Dec 2018 21:53:22 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id E96F22D7E2 for ; Fri, 14 Dec 2018 21:53:21 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id DD36E2D800; Fri, 14 Dec 2018 21:53:21 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id CBFA32D7E2 for ; Fri, 14 Dec 2018 21:53:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731297AbeLNVxT (ORCPT ); Fri, 14 Dec 2018 16:53:19 -0500 Received: from mx1.redhat.com ([209.132.183.28]:56074 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731293AbeLNVxS (ORCPT ); Fri, 14 Dec 2018 16:53:18 -0500 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id D2AA583F63; Fri, 14 Dec 2018 21:53:17 +0000 (UTC) Received: from llong.com (dhcp-17-223.bos.redhat.com [10.18.17.223]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4AF7B5FCD0; Fri, 14 Dec 2018 21:53:12 +0000 (UTC) From: Waiman Long To: Alexander Viro , Jonathan Corbet , Andrew Morton Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-doc@vger.kernel.org, "Luis R. Rodriguez" , Kees Cook , Linus Torvalds , Jan Kara , "Paul E. McKenney" , Ingo Molnar , Miklos Szeredi , Matthew Wilcox , Larry Woodman , James Bottomley , "Wangkai (Kevin C)" , Michal Hocko , Waiman Long Subject: [RESEND PATCH v4 0/3] fs/dcache: Track # of negative dentries Date: Fri, 14 Dec 2018 16:53:01 -0500 Message-Id: <1544824384-17668-1-git-send-email-longman@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Fri, 14 Dec 2018 21:53:18 +0000 (UTC) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP v3->v4: - Drop patch 4 as it is just a minor optimization. - Add a cc:stable tag to patch 1. - Clean up some comments in patch 3. v2->v3: - With confirmation that the dummy array in dentry_stat structure was never a replacement of a previously used field, patch 3 is now reverted back to use one of dummy field as the negative dentry count instead of adding a new field. v1->v2: - Clarify what the new nr_dentry_negative per-cpu counter is tracking and open-code the increment and decrement as suggested by Dave Chinner. - Append the new nr_dentry_negative count as the 7th element of dentry-state instead of replacing one of the dummy entries. - Remove patch "fs/dcache: Make negative dentries easier to be reclaimed" for now as I need more time to think about what to do with it. - Add 2 more patches to address issues found while reviewing the dentry code. - Add another patch to change the conditional branch of nr_dentry_negative accounting to conditional move so as to reduce the performance impact of the accounting code. This patchset addresses 2 issues found in the dentry code and adds a new nr_dentry_negative per-cpu counter to track the total number of negative dentries in all the LRU lists. Patch 1 fixes a bug in the accounting of nr_dentry_unused in shrink_dcache_sb(). Patch 2 removes the ____cacheline_aligned_in_smp tag from super_block LRU lists. Patch 3 adds the new nr_dentry_negative per-cpu counter. Various filesystem related tests were run and no statistically significant changes in performance outside of the possible noise range was observed. Waiman Long (3): fs/dcache: Fix incorrect nr_dentry_unused accounting in shrink_dcache_sb() fs: Don't need to put list_lru into its own cacheline fs/dcache: Track & report number of negative dentries Documentation/sysctl/fs.txt | 26 ++++++++++++++++---------- fs/dcache.c | 38 +++++++++++++++++++++++++++++++++----- include/linux/dcache.h | 7 ++++--- include/linux/fs.h | 9 +++++---- 4 files changed, 58 insertions(+), 22 deletions(-)