From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 09F1DC4332F for ; Mon, 14 Nov 2022 22:50:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237722AbiKNWus (ORCPT ); Mon, 14 Nov 2022 17:50:48 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44644 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237543AbiKNWuq (ORCPT ); Mon, 14 Nov 2022 17:50:46 -0500 Received: from mail-il1-x12f.google.com (mail-il1-x12f.google.com [IPv6:2607:f8b0:4864:20::12f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AC90C17068 for ; Mon, 14 Nov 2022 14:50:45 -0800 (PST) Received: by mail-il1-x12f.google.com with SMTP id m15so6536265ilq.2 for ; Mon, 14 Nov 2022 14:50:45 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ttaylorr-com.20210112.gappssmtp.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=J8CEQalS+5RvNyEGdYR1fzZ/XdS0NQjy/42E4OjfwiI=; b=pKZByidSgcb48s13yRLhVRyYpWAh/t/5E06Euu7oI3lNIDpvfspD13VchNKpa2CEQE zUwRG49cj+tp3SW3v2QRPDyen595Sl3WIMZpFfm5/iQyUf2uuL6FpN9PJDCj3H5ovfCe aMpGdqfzgPBJqZ3t4IVw7vPlByAEUMx0K8HRnA2MP9ngW8IKDCoBe1dgceCPsBYZOdk6 byxdNitGWCJO51iEyLIepcLCfktr1O3ItsOv6mglL1EVTLQgZoKEuFpqmk+YjRMgBdVc qZ4pSZ1x3asCXAeJBpwfIsSWYXynSK8I0yIAQ6PTW+q5jOM5k/na+aA7H0+hvCSsY3Hc U3NQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=J8CEQalS+5RvNyEGdYR1fzZ/XdS0NQjy/42E4OjfwiI=; b=8HZqC00yDDK8ECIQOwSSAGqtP5G02nDMduh93F/osCpPGE0Hw7mTMiuoj0+XtvTze3 D8Fkpx6MbNSCTdbMcqKzCNEL4ip6VBlEdzPUX4OqMuTkRZjpp2SonD2iDmw2kEZIQe5N Jz2ytb3jkco/iAy33exJl63ha81csBp6SqcRFAFtCgoaHJ5YMApbjgDcxjdgQdUkR7l7 xdeNo2We7STLA2QouiduFSucN5E0eFAsvs0HrPiDNGY7tqXCwd8015Fxv2DiEUHQWnZX 4FHl0AYpu4F0S9GKTz6P+0JSfBUCGEWf1zryvJg3MsrDfr52mzdKC0olQ4jr4V8tQTYu Kofg== X-Gm-Message-State: ANoB5pkZ+6h0zfWo1mItEZTQe8UTOx9skhoc2xis6L9VY7NW5usJwZZF baRVHcGMipuv1zrA+ypftGKFLw== X-Google-Smtp-Source: AA0mqf5ZZ/iqqg9ZkztD2egehU8WTCtkq4UV+rDrcMKyKWE8X3NyD5McA0btbDgegtLq1L6xmxcaCg== X-Received: by 2002:a92:c108:0:b0:300:ee15:9973 with SMTP id p8-20020a92c108000000b00300ee159973mr7334497ile.234.1668466245051; Mon, 14 Nov 2022 14:50:45 -0800 (PST) Received: from localhost (104-178-186-189.lightspeed.milwwi.sbcglobal.net. [104.178.186.189]) by smtp.gmail.com with ESMTPSA id u18-20020a92d1d2000000b00300b6effa1dsm4311133ilg.31.2022.11.14.14.50.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 14 Nov 2022 14:50:44 -0800 (PST) Date: Mon, 14 Nov 2022 17:50:43 -0500 From: Taylor Blau To: Jeff King Cc: Taylor Blau , Teng Long , avarab@gmail.com, derrickstolee@github.com, git@vger.kernel.org, gitster@pobox.com, tenglong.tl@alibaba-inc.com Subject: Re: [PATCH v3 1/2] pack-bitmap.c: remove unnecessary "open_pack_index()" calls Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org On Mon, Nov 14, 2022 at 05:31:18PM -0500, Jeff King wrote: > Yeah, I agree that 1k is a lot more compelling. The big impractical > thing I think is that if the bitmapped pack is older (and it usually > is), then we'd often open all the other packs anyway: > > - if the start of the traversal is in the bitmapped pack, then we > fruitlessly open each of the others looking for the object (since > the bitmapped one will come last in the reverse-chronological > sorting) > > - if it isn't in the bitmapped pack, then we'll end up opening all > those other packs anyway to fill out the bitmap (since by definition > it can't be included in the on-disk bitmaps) > > So I'd be surprised if it ever mattered in the real world. Though again, > I think the new code is less surprising in general, and could matter if > we changed other things (e.g., if we prioritized lookups in a pack with > a .bitmap). I completely agree. It's definitely worth doing purely based on the principle of least-surprise. But the potential performance improvements are just gravy on top ;-). Thanks, Taylor