From patchwork Mon Aug 2 09:38:10 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Patrick Steinhardt X-Patchwork-Id: 12413643 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EB208C4338F for ; Mon, 2 Aug 2021 09:38:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D044361057 for ; Mon, 2 Aug 2021 09:38:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233128AbhHBJi1 (ORCPT ); Mon, 2 Aug 2021 05:38:27 -0400 Received: from wout2-smtp.messagingengine.com ([64.147.123.25]:52779 "EHLO wout2-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232871AbhHBJiX (ORCPT ); Mon, 2 Aug 2021 05:38:23 -0400 Received: from compute6.internal (compute6.nyi.internal [10.202.2.46]) by mailout.west.internal (Postfix) with ESMTP id 1EE02320082A; Mon, 2 Aug 2021 05:38:14 -0400 (EDT) Received: from mailfrontend1 ([10.202.2.162]) by compute6.internal (MEProxy); Mon, 02 Aug 2021 05:38:14 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=pks.im; h=date :from:to:cc:subject:message-id:references:mime-version :content-type:in-reply-to; s=fm1; bh=GZHlia91WZIVolUD7vLI/abMu+h Hfie34ywewvxJ9bA=; b=hkNtxVNWNaz5SvigUTZGluKROknAN8Ek+JErZdcxyou gqn5yvWmfMQanLtFLDrGKw3U8QhG3wwZb7b2gZLNp1U6fbOFIDljZz3aVeqi7MGI IhsBazaZ038fy0sZBSvHdVeoihWVPK5K/Eu59vUIsV5WddIRlPE5hYdhysX9iyeI 0WEHuchAbsuALXFaYNZC56Ta/64WtHXgCoRni2QSLMpUxrSB7WMxw9w6sH+88DL6 o6LL5/J6VJj2fJ8mvzBMxEO3CvvsZ22xEmE7zlnU/tya4oLWnU0VyFz+N5AlxuG6 0fLVSPZg2kwAQTbP8gPeX2yxqUbwsWm18m5eTdGBSgA== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to:x-me-proxy :x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s=fm3; bh=GZHlia 91WZIVolUD7vLI/abMu+hHfie34ywewvxJ9bA=; b=upvdhaDQHQCbeiRqx8wM0T HnRmTHU7VVQykfB1dpXj/LKFejUmN3ep1Sk4W3zxtOn7QmHY+4VeBnE2k6kxe68f rWJYfIO/nGAx4+JdQk5B4Z1Xo3W/h1fP3Ymc9qwyREaRWgWDxc4jFRqC4l0ikb4H np7sX8FIeEjr7uQeDwYcE+71A0yPdqMLa++6Fqsw5ndzUbtsgCL0VRBZ223Ipgnl PGJM+lpreDGZxH1iXAJ7pFQL1eNYVWp9CBmqkN0VysaCpBN7VfKm5hgTGtmoWSZL L4vO0DLunP7azc//nQFNwpiSistU6zV5cxUYPu5zTdJuG4PI+wsfVBIpuaCPlugA == X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedvtddriedvgddugecutefuodetggdotefrodftvf curfhrohhfihhlvgemucfhrghsthforghilhdpqfgfvfdpuffrtefokffrpgfnqfghnecu uegrihhlohhuthemuceftddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmdenuc fjughrpeffhffvuffkfhggtggujgesghdtreertddtjeenucfhrhhomheprfgrthhrihgt khcuufhtvghinhhhrghrughtuceophhssehpkhhsrdhimheqnecuggftrfgrthhtvghrnh ephefgjeeuveejteduhefgffefffdvjeefjeeivdekfffgkeeugfehveetueefleeknecu vehluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehmrghilhhfrhhomhepphhssehpkh hsrdhimh X-ME-Proxy: Received: by mail.messagingengine.com (Postfix) with ESMTPA; Mon, 2 Aug 2021 05:38:12 -0400 (EDT) Received: from localhost (ncase [10.192.0.11]) by vm-mail.pks.im (OpenSMTPD) with ESMTPSA id d2bad18a (TLSv1.3:TLS_AES_256_GCM_SHA384:256:NO); Mon, 2 Aug 2021 09:38:12 +0000 (UTC) Date: Mon, 2 Aug 2021 11:38:10 +0200 From: Patrick Steinhardt To: git@vger.kernel.org Cc: Jeff King , Felipe Contreras , SZEDER =?iso-8859-1?q?G=E1bor?= , Chris Torek , =?iso-8859-1?q?=C6var_Arnfj=F6r=F0?= Bjarmason , Junio C Hamano , Taylor Blau Subject: [PATCH v3 3/4] revision: avoid loading object headers multiple times Message-ID: References: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org When loading references, we try to optimize loading of commits by using the commit graph. To do so, we first need to determine whether the object actually is a commit or not, which is why we always execute `oid_object_info()` first. Like this, we'll unpack the object header of each object first. This pattern can be quite inefficient in case many references point to the same commit: if the object didn't end up in the cached objects, then we'll repeatedly unpack the same object header, even if we've already seen the object before. Optimize this pattern by using `lookup_unknown_object()` first in order to determine whether we've seen the object before. If so, then we don't need to re-parse the header but can directly use its object information and thus gain a modest performance improvement. Executed in a real-world repository with around 2.2 million references: Benchmark #1: HEAD~: rev-list --unsorted-input --objects --quiet --not --all --not $newrev Time (mean ± σ): 4.771 s ± 0.238 s [User: 4.440 s, System: 0.330 s] Range (min … max): 4.539 s … 5.219 s 10 runs Benchmark #2: HEAD: rev-list --unsorted-input --objects --quiet --not --all --not $newrev Time (mean ± σ): 4.454 s ± 0.037 s [User: 4.122 s, System: 0.332 s] Range (min … max): 4.375 s … 4.496 s 10 runs Summary 'HEAD: rev-list --unsorted-input --objects --quiet --not --all --not $newrev' ran 1.07 ± 0.05 times faster than 'HEAD~: rev-list --unsorted-input --objects --quiet --not --all --not $newrev' The downside is that `lookup_unknown_object()` is forced to always allocate an object such that it's big enough to host all object types' structs and thus we may waste memory here. This tradeoff is probably worth it though considering the following struct sizes: - commit: 72 bytes - tree: 56 bytes - blob: 40 bytes - tag: 64 bytes Assuming that in almost all repositories, most references will point to either a tag or a commit, we'd have a modest increase in memory consumption of about 12.5% here. Signed-off-by: Patrick Steinhardt --- revision.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/revision.c b/revision.c index f06a5d63a3..671b6d6513 100644 --- a/revision.c +++ b/revision.c @@ -359,14 +359,22 @@ static struct object *get_reference(struct rev_info *revs, const char *name, const struct object_id *oid, unsigned int flags) { - struct object *object; + struct object *object = lookup_unknown_object(revs->repo, oid); + + if (object->type == OBJ_NONE) { + int type = oid_object_info(revs->repo, oid, NULL); + if (type < 0 || !object_as_type(object, type, 1)) { + object = NULL; + goto out; + } + } /* * If the repository has commit graphs, repo_parse_commit() avoids * reading the object buffer, so use it whenever possible. */ - if (oid_object_info(revs->repo, oid, NULL) == OBJ_COMMIT) { - struct commit *c = lookup_commit(revs->repo, oid); + if (object->type == OBJ_COMMIT) { + struct commit *c = (struct commit *) object; if (!repo_parse_commit(revs->repo, c)) object = (struct object *) c; else @@ -375,6 +383,7 @@ static struct object *get_reference(struct rev_info *revs, const char *name, object = parse_object(revs->repo, oid); } +out: if (!object) { if (revs->ignore_missing) return object;