From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 2512414900B; Fri, 26 Apr 2024 15:06:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714143996; cv=none; b=d/1L6GdNNiYfIL04KhO3rZOHCsLKyGUIupmVBgc9SGmyvgJ87S28RYcagO4H/pbS6JiobrgdhjM4fTQtc1ElS/aBK3yQRvEcYM8mne9PBvdub3E47/FfW0ccTcLMbl4nWgN0a5xT0zwXKMkDH+ZW47qXPtCmHhmzDmqB1jmr+J4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714143996; c=relaxed/simple; bh=LNCspRv71TcIP3ZbJ/TMAX90WJJx42Sm7l811YLKB4s=; h=Message-ID:Date:MIME-Version:Subject:To:References:Cc:From: In-Reply-To:Content-Type; b=hUE1+WyENVgS8He6/f2htAGr+Gxdq9PFsQtKGycvi0R0YP8k/GhtzaDqCYA+M/IkXNOoYr00riEyY4eacb4kq9Q3JfsTcvDZFACD25csJMWyrLEQPL0vsXWrH+Izja4784/2OwrarmBfkohjFcQVeh1WVJ449ez8PejqtqOxuLU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 460FD1007; Fri, 26 Apr 2024 08:07:02 -0700 (PDT) Received: from [192.168.1.216] (usa-sjc-mx-foss1.foss.arm.com [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id C09AC3F73F; Fri, 26 Apr 2024 08:06:31 -0700 (PDT) Message-ID: <3e54fea7-2a37-4774-8a6a-85f75cc4a9ea@arm.com> Date: Fri, 26 Apr 2024 16:06:29 +0100 Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1] perf tests: Run tests in parallel by default To: Ian Rogers References: <20240301174711.2646944-1-irogers@google.com> Content-Language: en-US Cc: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Adrian Hunter , Kan Liang , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org From: James Clark In-Reply-To: <20240301174711.2646944-1-irogers@google.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 01/03/2024 17:47, Ian Rogers wrote: > Switch from running tests sequentially to running in parallel by > default. Change the opt-in '-p' or '--parallel' flag to '-S' or > '--sequential'. > > On an 8 core tigerlake an address sanitizer run time changes from: > 326.54user 622.73system 6:59.91elapsed 226%CPU > to: > 973.02user 583.98system 3:01.17elapsed 859%CPU > > So over twice as fast, saving 4 minutes. > Apologies for not replying earlier before this was applied. But IMO this isn't a good default. Tests that use things like exclusive PMUs (Coresight for example) can never pass when run in parallel. For CI it's arguable whether you'd want to trade stability for speed. And for interactive sessions there was already the --parallel option which was easy to add and have it in your bash history. Now we've changed the default, any CI will need to be updated to add --sequential if it wants all the tests to pass. Maybe we could do some hack and gate it on interactive vs non interactive sessions, but that might be getting too clever. (Or a "don't run in parallel" flag on certain tests) Thanks James