From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS31976 209.132.180.0/23 X-Spam-Status: No, score=-3.7 required=3.0 tests=AWL,BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI shortcircuit=no autolearn=ham autolearn_force=no version=3.4.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by dcvr.yhbt.net (Postfix) with ESMTP id 013C91F453 for ; Mon, 29 Oct 2018 00:48:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725967AbeJ2JeZ (ORCPT ); Mon, 29 Oct 2018 05:34:25 -0400 Received: from mail-wr1-f68.google.com ([209.85.221.68]:41485 "EHLO mail-wr1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725879AbeJ2JeZ (ORCPT ); Mon, 29 Oct 2018 05:34:25 -0400 Received: by mail-wr1-f68.google.com with SMTP id x12-v6so6813048wrw.8 for ; Sun, 28 Oct 2018 17:48:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:from:to:cc:subject:references:date:in-reply-to:message-id :user-agent:mime-version; bh=OQG50LGTCQwP8whhr3M7KLnJCDNm1nl4yoEes0U3tjc=; b=Cm26zk+/LtziUxZ5Nu/fGKCCOvK+NqZbwSgXb0yfftV6PtK1PmxeCqU0aZ6FAeCzlY 75IyJK01YN6rZjwKtgbcPmajMty9zMPQ9EuSCmXPSfIgmFIuA+lnWHyHfaahYSHM1wQG 2iLborKMJGg7IaHdRV/sTgPjAvIJsOea4CMYjMIgEN3rjgBX6JtWQfTvBhbprQRLvKrf 18NmjCScNnh/R+RG2bLxbL0Y5apNRow6uvt404gSx8WbjkjJCmW5c6917q2MhLeKOJOp oeV6ttlVUC1tlJHwYPpM4auP4tmo7h9Gc4hfkfQqUICrQ9zXykNQAYNMqT2rP7z0J1aT k5xQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:from:to:cc:subject:references:date :in-reply-to:message-id:user-agent:mime-version; bh=OQG50LGTCQwP8whhr3M7KLnJCDNm1nl4yoEes0U3tjc=; b=bwnI08hEVL81cbMal1g3Km5H6NeNo7hQrcb7Dcu5iN9nF4+zdWbrfX5ku3DicpJ2sn ThMDV1HWLhWz4enDgy4XKjr6nFwU5zoVgyp74gR4WhpAQ4JN/9mOXntE+MjMWZi8Y19E 7rs9l3hIQb1mObf8MDwqrsIxduBhKg1OHn1qZl0auJG2nS749VEXThqqfUyJfBUDUtNZ Ne9TSUt43MyW4Tn2m1wDAYumPmwCKmkDp/hwN9jMVBpkvCwk+Eo+DZaow69nlnVblszg 1tSs18KgREoZE81/LxyWs7caWP4pqZlGLgZpNVWqonwTx9JahPrAMAaGUX4LHCT4BiNJ vWIQ== X-Gm-Message-State: AGRZ1gKnBZHfT0bnfM7byZDJmq6XteGb9tY/S2/JUDH/YcFyI+WEw5Z2 qMRnKeCN2rzrUCgwLBDq7uo= X-Google-Smtp-Source: AJdET5dmdtQrGZadZosuqZCjfXssaYBkhyTbAXDijf/gKmXRVwJKp94qKP1ze6ujLZhm/Po3TjbRtQ== X-Received: by 2002:adf:80a3:: with SMTP id 32-v6mr13428066wrl.231.1540774085229; Sun, 28 Oct 2018 17:48:05 -0700 (PDT) Received: from localhost (168.50.187.35.bc.googleusercontent.com. [35.187.50.168]) by smtp.gmail.com with ESMTPSA id k18-v6sm10325119wrp.65.2018.10.28.17.48.03 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Sun, 28 Oct 2018 17:48:03 -0700 (PDT) From: Junio C Hamano To: Jeff King Cc: =?utf-8?B?w4Z2YXIgQXJuZmrDtnLDsA==?= Bjarmason , "Jansen\, Geert" , "git\@vger.kernel.org" , Christian Couder Subject: Re: [RFC PATCH] index-pack: improve performance on NFS References: <87o9bgl9yl.fsf@evledraar.gmail.com> <20181027093300.GA23974@sigill.intra.peff.net> Date: Mon, 29 Oct 2018 09:48:02 +0900 In-Reply-To: <20181027093300.GA23974@sigill.intra.peff.net> (Jeff King's message of "Sat, 27 Oct 2018 05:33:01 -0400") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Jeff King writes: > Of course any cache raises questions of cache invalidation, but I think > we've already dealt with that for this case. When we use > OBJECT_INFO_QUICK, that is a sign that we want to make this kind of > accuracy/speed tradeoff (which does a similar caching thing with > packfiles). > > So putting that all together, could we have something like: I think this conceptually is a vast improvement relative to ".cloning" optimization. Obviously this does not have the huge downside of the other approach that turns the collision detection completely off. A real question is how much performance gain, relative to ".cloning" thing, this approach gives us. If it gives us 80% or more of the gain compared to doing no checking, I'd say we have a clear winner. > That's mostly untested, but it might be enough to run some timing tests > with. I think if we want to pursue this, we'd want to address the bits I > mentioned in the comments, and look at unifying this with the loose > cache from cc817ca3ef (which if I had remembered we added, probably > would have saved some time writing the above ;) ). Yup.