From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS31976 209.132.180.0/23 X-Spam-Status: No, score=-2.7 required=3.0 tests=AWL,BAYES_00,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,RCVD_IN_DNSWL_HI,RCVD_IN_SORBS_SPAM, RP_MATCHES_RCVD,T_DKIM_INVALID shortcircuit=no autolearn=no autolearn_force=no version=3.4.0 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by dcvr.yhbt.net (Postfix) with ESMTP id 253C620281 for ; Wed, 24 May 2017 04:45:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965953AbdEXEpl (ORCPT ); Wed, 24 May 2017 00:45:41 -0400 Received: from mail-pf0-f194.google.com ([209.85.192.194]:35743 "EHLO mail-pf0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1762012AbdEXEpe (ORCPT ); Wed, 24 May 2017 00:45:34 -0400 Received: by mail-pf0-f194.google.com with SMTP id u26so31552755pfd.2 for ; Tue, 23 May 2017 21:45:34 -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:content-transfer-encoding; bh=bdt3QkEA4OanJkCWI40yNnz6yF4OBaZC8YjSUUOi9qM=; b=UYqA2yZPyDnwn1Y5pJcp1giUUf/ICFD+AgBw/4kWNXZJNPxTA4yqfZB/HF7Nkdwxdl IqpYerwrM/Zb8RJbIomrpJd0fO0KMWzyaRJRd1FYSlzVfp9mjNLS9jtPZxlXbmKLFzuJ WkHFRfQ2ZELaeZMFDVZlkQ4jHU2aRZ/lxFwnvGQcCSCTdGidSBJpJIa0wjRXNA3xbPKY hKE4zaL/1n6KiUWR7GlO/vONsqPHsZs0XC7jjhBl07mf/WzBDpz3fCIAJEo/NY8qggEP cxOVTp2hhCDp15uJ+elMkNBTyu430N0G/JaaBp4PThhJp5xBCq/AnaU05IZRa3xMyBmc ep8A== 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 :content-transfer-encoding; bh=bdt3QkEA4OanJkCWI40yNnz6yF4OBaZC8YjSUUOi9qM=; b=aBf1PXYbYBqmA4TEM0bf2JGoFXvgKMHj64ILyJB6l40dZGoeYI+10IH8BGS50zggBT gknZUgzEB0dqpylf28gx41+p6mbYNWj3miRe59eyeSZhh95AzFiV9zL7jg3RiMlmd/oI dD53B6mUvZMJ5u62/q5MtoXjpujQbnWHgJfvH9gzpxlx5P6c3Xra+WyyXdoXq2DEBkux 4AMBD8ldM8gdlLo4zp0UNxjlUCV/utNVCJMaw2w54gBHkR2w+DRfOWSDvj14nXPLWR70 H85nhF55wBvWdKmxyfKdNgdnlOzHkzJJKhoYt9qjckx7DjCJvLvYOqZb9O8fx6UhOcdy TD7A== X-Gm-Message-State: AODbwcDO59xaT/mSUfO5yxYWnFNh6s2PIo1aDc2U3G+fMWt+6Dk8hvn9 OY03iRQxvMRqcQ== X-Received: by 10.98.155.154 with SMTP id e26mr36480460pfk.24.1495601134278; Tue, 23 May 2017 21:45:34 -0700 (PDT) Received: from localhost ([2620:0:1000:8622:167:7063:293b:a24d]) by smtp.gmail.com with ESMTPSA id b65sm4572528pfl.48.2017.05.23.21.45.33 (version=TLS1_2 cipher=AES128-SHA bits=128/128); Tue, 23 May 2017 21:45:33 -0700 (PDT) From: Junio C Hamano To: =?utf-8?B?w4Z2YXIgQXJuZmrDtnLDsA==?= Bjarmason Cc: git@vger.kernel.org, Jeff King , Jeffrey Walton , =?utf-8?Q?Micha=C5=82?= Kiedrowicz , J Smith , Victor Leschuk , =?utf-8?B?Tmd1eeG7hW4gVGjDoWkgTmfhu41j?= Duy , Fredrik Kuivinen , Brandon Williams , Stefan Beller , Johannes Schindelin , Simon Ruderich Subject: Re: [PATCH v2 2/7] grep: skip pthreads overhead when using one thread References: <20170523192453.14172-1-avarab@gmail.com> <20170523192453.14172-3-avarab@gmail.com> Date: Wed, 24 May 2017 13:45:32 +0900 In-Reply-To: <20170523192453.14172-3-avarab@gmail.com> (=?utf-8?B?IsOGdmFy?= =?utf-8?B?IEFybmZqw7Zyw7A=?= Bjarmason"'s message of "Tue, 23 May 2017 19:24:48 +0000") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Ævar Arnfjörð Bjarmason writes: > Skip the administrative overhead of using pthreads when only using one > thread. Instead take the non-threaded path which would be taken under > NO_PTHREADS. > > The threading support was initially added in commit > 5b594f457a ("Threaded grep", 2010-01-25) with a hardcoded compile-time > number of 8 threads. Later the number of threads was made configurable > in commit 89f09dd34e ("grep: add --threads= option and > grep.threads configuration", 2015-12-15). > > That change did not add any special handling for --threads=1. Now we > take a slightly faster path by skipping thread handling entirely when > 1 thread is requested. OK, this is what Peff and you were discussing in the earlier round, having the controller do the work himself, instead of sitting and waiting for a sole worker to finish the work. Looks good. Thanks. > > Signed-off-by: Ævar Arnfjörð Bjarmason > --- > builtin/grep.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/builtin/grep.c b/builtin/grep.c > index 12e62fcbf3..bd008cb100 100644 > --- a/builtin/grep.c > +++ b/builtin/grep.c > @@ -1238,6 +1238,8 @@ int cmd_grep(int argc, const char **argv, const char *prefix) > num_threads = GREP_NUM_THREADS_DEFAULT; > else if (num_threads < 0) > die(_("invalid number of threads specified (%d)"), num_threads); > + if (num_threads == 1) > + num_threads = 0; > #else > if (num_threads) > warning(_("no threads support, ignoring --threads"));