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Biederman) To: Junxiao Bi Cc: Matthew Wilcox , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Matthew Wilcox , Srinivas Eeda , "joe.jin\@oracle.com" , Wengang Wang References: <54091fc0-ca46-2186-97a8-d1f3c4f3877b@oracle.com> <20200618233958.GV8681@bombadil.infradead.org> <877dw3apn8.fsf@x220.int.ebiederm.org> <2cf6af59-e86b-f6cc-06d3-84309425bd1d@oracle.com> <87bllf87ve.fsf_-_@x220.int.ebiederm.org> Date: Fri, 19 Jun 2020 12:24:41 -0500 In-Reply-To: (Junxiao Bi's message of "Fri, 19 Jun 2020 08:56:21 -0700") Message-ID: <87k1036k9y.fsf@x220.int.ebiederm.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-XM-SPF: eid=1jmKp1-0004bC-7P;;;mid=<87k1036k9y.fsf@x220.int.ebiederm.org>;;;hst=in02.mta.xmission.com;;;ip=68.227.160.95;;;frm=ebiederm@xmission.com;;;spf=neutral X-XM-AID: U2FsdGVkX18t/kZAHYChf4fQBy2tfa9zm0fEa/HZ2QQ= X-SA-Exim-Connect-IP: 68.227.160.95 X-SA-Exim-Mail-From: ebiederm@xmission.com X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on sa08.xmission.com X-Spam-Level: X-Spam-Status: No, score=-3.3 required=8.0 tests=ALL_TRUSTED,BAYES_00, DCC_CHECK_NEGATIVE,T_TM2_M_HEADER_IN_MSG,XMSubLong autolearn=disabled version=3.4.2 X-Spam-Report: * -1.0 ALL_TRUSTED Passed through trusted hosts only via SMTP * -3.0 BAYES_00 BODY: Bayes spam probability is 0 to 1% * [score: 0.0096] * 0.7 XMSubLong Long Subject * 0.0 T_TM2_M_HEADER_IN_MSG BODY: No description available. * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa08 0; Body=1 Fuz1=1 Fuz2=1] X-Spam-DCC: ; sa08 0; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: ;Junxiao Bi X-Spam-Relay-Country: X-Spam-Timing: total 540 ms - load_scoreonly_sql: 0.06 (0.0%), signal_user_changed: 13 (2.5%), b_tie_ro: 12 (2.1%), parse: 1.08 (0.2%), extract_message_metadata: 3.9 (0.7%), get_uri_detail_list: 0.92 (0.2%), tests_pri_-1000: 4.0 (0.7%), tests_pri_-950: 1.55 (0.3%), tests_pri_-900: 1.29 (0.2%), tests_pri_-90: 123 (22.8%), check_bayes: 121 (22.3%), b_tokenize: 3.8 (0.7%), b_tok_get_all: 5 (1.0%), b_comp_prob: 1.50 (0.3%), b_tok_touch_all: 105 (19.5%), b_finish: 1.53 (0.3%), tests_pri_0: 373 (69.1%), check_dkim_signature: 0.84 (0.2%), check_dkim_adsp: 2.8 (0.5%), poll_dns_idle: 1.21 (0.2%), tests_pri_10: 2.2 (0.4%), tests_pri_500: 7 (1.2%), rewrite_mail: 0.00 (0.0%) Subject: Re: [PATCH] proc: Avoid a thundering herd of threads freeing proc dentries X-Spam-Flag: No X-SA-Exim-Version: 4.2.1 (built Thu, 05 May 2016 13:38:54 -0600) X-SA-Exim-Scanned: Yes (on in02.mta.xmission.com) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Junxiao Bi writes: > Hi Eric, > > The patch didn't improve lock contention. Which raises the question where is the lock contention coming from. Especially with my first variant. Only the last thread to be reaped would free up anything in the cache. Can you comment out the call to proc_flush_pid entirely? That will rule out the proc_flush_pid in d_invalidate entirely. The only candidate I can think of d_invalidate aka (proc_flush_pid) vs ps. Eric