From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS31976 209.132.180.0/23 X-Spam-Status: No, score=-4.0 required=3.0 tests=AWL,BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by dcvr.yhbt.net (Postfix) with ESMTP id A8D08211B5 for ; Tue, 22 Jan 2019 07:28:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727181AbfAVH2L (ORCPT ); Tue, 22 Jan 2019 02:28:11 -0500 Received: from cloud.peff.net ([104.130.231.41]:43610 "HELO cloud.peff.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1726423AbfAVH2L (ORCPT ); Tue, 22 Jan 2019 02:28:11 -0500 Received: (qmail 6567 invoked by uid 109); 22 Jan 2019 07:28:11 -0000 Received: from Unknown (HELO peff.net) (10.0.1.2) by cloud.peff.net (qpsmtpd/0.94) with SMTP; Tue, 22 Jan 2019 07:28:11 +0000 Authentication-Results: cloud.peff.net; auth=none Received: (qmail 3580 invoked by uid 111); 22 Jan 2019 07:28:14 -0000 Received: from sigill.intra.peff.net (HELO sigill.intra.peff.net) (10.0.0.7) by peff.net (qpsmtpd/0.94) with (ECDHE-RSA-AES256-GCM-SHA384 encrypted) SMTP; Tue, 22 Jan 2019 02:28:14 -0500 Authentication-Results: peff.net; auth=none Received: by sigill.intra.peff.net (sSMTP sendmail emulation); Tue, 22 Jan 2019 02:28:09 -0500 Date: Tue, 22 Jan 2019 02:28:09 -0500 From: Jeff King To: Duy Nguyen Cc: Patrick Hogg , Git Mailing List , Junio C Hamano , Johannes Schindelin , Elijah Newren Subject: Re: [PATCH v2] pack-objects: Use packing_data lock instead of read_mutex Message-ID: <20190122072809.GA28975@sigill.intra.peff.net> References: <20190119154337.6556-1-phogg@novamoon.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org On Mon, Jan 21, 2019 at 05:02:33PM +0700, Duy Nguyen wrote: > > As I mentioned in the prior thread I think that it will be simpler > > to simply use the existing lock in packing_data instead of moving > > read_mutex. I can go back to simply moving read_mutex to the > > packing_data struct if that that is preferable, though. > > In early iterations of these changes, I think we hit high contention > when sharing the mutex [1]. I don't know if we will hit the same > performance problem again with this patch. It would be great if Elijah > with his zillion core machine could test this out. Otherwise it may be > just safer to keep the two mutexes separate. > > [1] http://public-inbox.org/git/20180720052829.GA3852@sigill.intra.peff.net/ I haven't been following this thread closely, but I still have access to a 40-core machine if you'd like me to time anything. It sounds like _this_ patch is the more fine-grained one. Is the more coarse-grained one already written? -Peff