From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 59676 invoked by alias); 27 Mar 2017 16:09:44 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Received: (qmail 59663 invoked by uid 89); 27 Mar 2017 16:09:43 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.9 required=5.0 tests=BAYES_00,RP_MATCHES_RCVD,SPF_HELO_PASS autolearn=ham version=3.3.2 spammy=throughput, Hx-languages-length:1299 X-HELO: mx1.redhat.com DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com BBD0864A78 Authentication-Results: ext-mx02.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx02.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=longman@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com BBD0864A78 Subject: Re: [PATCH v2] rwlock: Fix explicit hand-over. To: Torvald Riegel , Florian Weimer References: <1490471341.26906.366.camel@redhat.com> <87inmxkt67.fsf@mid.deneb.enyo.de> <1490482860.26906.391.camel@redhat.com> Cc: GLIBC Devel , Carlos O'Donell From: Waiman Long Message-ID: Date: Mon, 27 Mar 2017 16:09:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.7.0 MIME-Version: 1.0 In-Reply-To: <1490482860.26906.391.camel@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-SW-Source: 2017-03/txt/msg00636.txt.bz2 On 03/25/2017 07:01 PM, Torvald Riegel wrote: > On Sat, 2017-03-25 at 21:17 +0100, Florian Weimer wrote: >> * Torvald Riegel: >> >>> + bool registered_while_in_write_phase =3D false; >>> if (__glibc_likely ((r & PTHREAD_RWLOCK_WRPHASE) =3D=3D 0)) >>> return 0; >>> + else >>> + registered_while_in_write_phase =3D true; >> Sorry, this doesn't look quite right. Isn't >> registered_while_in_write_phase always true? > Attached is a v2 patch. It's the same logic, but bigger. Most of this > increase is due to reformatting, but I also adapted some of the > comments. > I get two failures, but I guess these are either due to the bad internet > connectivity I currently have, or something at the resolver. > FAIL: resolv/mtrace-tst-leaks > FAIL: resolv/tst-leaks > > I have verified that the v2 patch did fix the hang that I saw with my microbenchmark. I also observed an increase in performance in the new rwlock code compared with the old one before the major rewrite. On a 4-socket 40-core 80-thread system, 80 parallel locking threads had an average per-thread throughput of 32,584 ops/s. The old rwlock code had a throughput of 13,411 only. So there is a more than 1.4X increase in performance. Tested-by: Waiman Long Cheers, Longman