From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on archive.lwn.net X-Spam-Level: X-Spam-Status: No, score=-5.8 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=ham autolearn_force=no version=3.4.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by archive.lwn.net (Postfix) with ESMTP id 6D9297D048 for ; Fri, 6 Jul 2018 22:28:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753707AbeGFW20 (ORCPT ); Fri, 6 Jul 2018 18:28:26 -0400 Received: from zeniv.linux.org.uk ([195.92.253.2]:54244 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753596AbeGFW20 (ORCPT ); Fri, 6 Jul 2018 18:28:26 -0400 Received: from viro by ZenIV.linux.org.uk with local (Exim 4.87 #1 (Red Hat Linux)) id 1fbZD4-00082f-NW; Fri, 06 Jul 2018 22:28:14 +0000 Date: Fri, 6 Jul 2018 23:28:14 +0100 From: Al Viro To: Waiman Long Cc: Jonathan Corbet , "Luis R. Rodriguez" , Kees Cook , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-doc@vger.kernel.org, Linus Torvalds , Jan Kara , "Paul E. McKenney" , Andrew Morton , Ingo Molnar , Miklos Szeredi , Matthew Wilcox , Larry Woodman , James Bottomley , "Wangkai (Kevin C)" Subject: Re: [PATCH v6 0/7] fs/dcache: Track & limit # of negative dentries Message-ID: <20180706222814.GE30522@ZenIV.linux.org.uk> References: <1530905572-817-1-git-send-email-longman@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1530905572-817-1-git-send-email-longman@redhat.com> User-Agent: Mutt/1.9.1 (2017-09-22) Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On Fri, Jul 06, 2018 at 03:32:45PM -0400, Waiman Long wrote: > With a 4.18 based kernel, the positive & negative dentries lookup rates > (lookups per second) after initial boot on a 2-socket 24-core 48-thread > 64GB memory system with and without the patch were as follows: ` > > Metric w/o patch neg_dentry_pc=0 neg_dentry_pc=1 > ------ --------- --------------- --------------- > Positive dentry lookup 584299 586749 582670 > Negative dentry lookup 1422204 1439994 1438440 > Negative dentry creation 643535 652194 641841 > > For the lookup rate, there isn't any signifcant difference with or > without the patch or with a zero or non-zero value of neg_dentry_pc. Sigh... What I *still* don't see (after all the iterations of the patchset) is any performance data on workloads that would be likely to feel the impact. Anything that seriously hits INCLUDE_PATH, for starters... -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html