From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qk1-f197.google.com (mail-qk1-f197.google.com [209.85.222.197]) by kanga.kvack.org (Postfix) with ESMTP id ED2A68E0001 for ; Wed, 12 Sep 2018 13:35:55 -0400 (EDT) Received: by mail-qk1-f197.google.com with SMTP id a70-v6so2259244qkb.16 for ; Wed, 12 Sep 2018 10:35:55 -0700 (PDT) Received: from mx1.redhat.com (mx3-rdu2.redhat.com. [66.187.233.73]) by mx.google.com with ESMTPS id z126-v6si1149333qkd.212.2018.09.12.10.35.54 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 12 Sep 2018 10:35:54 -0700 (PDT) From: Waiman Long Subject: [PATCH v4 0/3] fs/dcache: Track # of negative dentries Date: Wed, 12 Sep 2018 13:35:39 -0400 Message-Id: <1536773742-32687-1-git-send-email-longman@redhat.com> Sender: owner-linux-mm@kvack.org List-ID: 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 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(-) -- 1.8.3.1