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: AS53758 23.128.96.0/24 X-Spam-Status: No, score=-3.9 required=3.0 tests=AWL,BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI, SPF_HELO_PASS,SPF_PASS shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by dcvr.yhbt.net (Postfix) with ESMTP id A1B121F8C8 for ; Sat, 11 Sep 2021 17:03:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232149AbhIKREe (ORCPT ); Sat, 11 Sep 2021 13:04:34 -0400 Received: from cloud.peff.net ([104.130.231.41]:45076 "EHLO cloud.peff.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231765AbhIKREc (ORCPT ); Sat, 11 Sep 2021 13:04:32 -0400 Received: (qmail 12770 invoked by uid 109); 11 Sep 2021 17:03:18 -0000 Received: from Unknown (HELO peff.net) (10.0.1.2) by cloud.peff.net (qpsmtpd/0.94) with ESMTP; Sat, 11 Sep 2021 17:03:18 +0000 Authentication-Results: cloud.peff.net; auth=none Received: (qmail 22324 invoked by uid 111); 11 Sep 2021 17:03:18 -0000 Received: from coredump.intra.peff.net (HELO sigill.intra.peff.net) (10.0.0.2) by peff.net (qpsmtpd/0.94) with (TLS_AES_256_GCM_SHA384 encrypted) ESMTPS; Sat, 11 Sep 2021 13:03:18 -0400 Authentication-Results: peff.net; auth=none Date: Sat, 11 Sep 2021 13:03:17 -0400 From: Jeff King To: =?utf-8?B?UmVuw6k=?= Scharfe Cc: Git List , Junio C Hamano Subject: Re: [PATCH 3/3] packfile: use oidset for bad objects Message-ID: References: <4a702bfe-afd0-669a-c893-0262289c24b8@web.de> <14d48124-d8bb-aa34-aad0-4203d699e17e@web.de> <3d637be1-f89f-414c-19ef-65c3943457e9@web.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <3d637be1-f89f-414c-19ef-65c3943457e9@web.de> Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org On Sat, Sep 11, 2021 at 06:08:38PM +0200, René Scharfe wrote: > >> + nth_midxed_object_oid(&oid, m, pos); > >> + if (oidset_contains(&p->bad_objects, &oid)) > >> + return 0; > > > > Calling nth_midxed_object_oid() implies a memcpy() under the hood. In > > the old code, we'd skip that in the common case that we had no corrupt > > objects, but now we'll pay the cost regardless. memcpy() isn't _that_ > > expensive, but I'd expect this to be a relatively hot code path. > > > > Is it worth sticking all of this inside: > > > > if (oidset_size(&p->bad_objects)) > > > > ? > > Hard to say. It would certainly match the old code more closely. Is a > function call cheaper than copying 32 bytes? Depends on the CPU and > whether the hash is cached, I guess. And cached it probably is, because > the caller did a binary search for it.. You already have a function call for nth_midxed_object_oid(), so checking oidset_size() would be a strict improvement. > We can pass on the original oid to avoid the nth_midxed_object_oid() > call, but inlining the whole thing might even be nicer. Yeah, it occurs to me that oidset_size() would be a good candidate for inlining, if that's what you mean. -Peff