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 X-Spam-Level: X-Spam-Status: No, score=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 0B850C00523 for ; Wed, 8 Jan 2020 11:02:27 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id C1E55206DA for ; Wed, 8 Jan 2020 11:02:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="HZd62MwP" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C1E55206DA Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:41962 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ip96Y-0002DA-0P for qemu-devel@archiver.kernel.org; Wed, 08 Jan 2020 06:02:26 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:35552) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ip93D-0007RO-Gj for qemu-devel@nongnu.org; Wed, 08 Jan 2020 05:59:00 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ip93C-00037O-B8 for qemu-devel@nongnu.org; Wed, 08 Jan 2020 05:58:59 -0500 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:24257 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1ip93C-000377-88 for qemu-devel@nongnu.org; Wed, 08 Jan 2020 05:58:58 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1578481137; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:openpgp:openpgp; bh=kqLzPHnOBz0GvDYzxg1Y0gsqDEBWC/JehSDzf5oZ3+8=; b=HZd62MwPUtP3ChqfXgin5fCJolTQ42lv53K9A0YAlc9M+uuecPCp2niAzlPxcnDLasXqD3 X2pzxs81c28rElUhNIo57GLHrFtibcXLNjYOtjMh1QV/Rucsm3qzYFe2GZF57ufT9yhLlt 6B9GrBZgda3+RnCTe40twOiSuY3h0o8= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-163-pLEatL-hMMq6KMJr1PYfbw-1; Wed, 08 Jan 2020 05:58:57 -0500 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id E20C410054E3; Wed, 8 Jan 2020 10:58:55 +0000 (UTC) Received: from thuth.remote.csb (ovpn-117-114.ams2.redhat.com [10.36.117.114]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 2BB43649C1; Wed, 8 Jan 2020 10:58:48 +0000 (UTC) Subject: Re: Priority of -accel (was: [PATCH] tests/qemu-iotests: Update tests to recent desugarized -accel option) To: =?UTF-8?Q?Alex_Benn=c3=a9e?= , qemu-devel@nongnu.org References: <20200106130951.29873-1-philmd@redhat.com> <12334054-4ae7-e580-9727-2d322bfa2bda@redhat.com> <58eb34db-7d32-8b0e-d9ef-98648209486b@redhat.com> <656169fc-1abe-b521-20a3-e7041739b914@redhat.com> <20200107125451.GL3368802@redhat.com> <3241dff4-6223-404f-55d4-846991763046@redhat.com> <87d0bujkpe.fsf@linaro.org> From: Thomas Huth Openpgp: preference=signencrypt Message-ID: Date: Wed, 8 Jan 2020 11:58:47 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <87d0bujkpe.fsf@linaro.org> Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-MC-Unique: pLEatL-hMMq6KMJr1PYfbw-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 207.211.31.120 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , =?UTF-8?Q?Daniel_P=2e_Berrang=c3=a9?= , qemu-block@nongnu.org, Markus Armbruster , Wainer dos Santos Moschetta , Max Reitz , Paolo Bonzini , =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 08/01/2020 11.39, Alex Benn=C3=A9e wrote: >=20 > Thomas Huth writes: >=20 >> On 07/01/2020 13.54, Daniel P. Berrang=C3=A9 wrote: >>> On Tue, Jan 07, 2020 at 01:23:18PM +0100, Paolo Bonzini wrote: >>>> On 07/01/20 13:18, Thomas Huth wrote: >>>>> I don't think we need a separate priority parameter here. But IMHO it= 's >>>>> really rather common practice to prioritize the last option. So whil= e >>>>> it might be more "self-explanatory" to a CLI newbie if the first >>>>> occurrence got the highest priority, it might be rather confusing >>>>> instead for a CLI veteran...? >>>> >>>> Prioritising the last certainly makes sense for a choose-one-only >>>> option, but I'm not sure it's the same for a choose-best option. Afte= r >>>> all it was -machine accel=3Dkvm:tcg, not -machine accel=3Dtcg:kvm... >>> >>> IIUC, the main use case for specifying multiple accelerators is >>> so that lazy invokations can ask for a hardware virt, but then get >>> fallback to TCG if not available. For things that should be platform >>> portabile, there's more than just kvm to consider though, as we have >>> many accelerators. Listing all possible accelerators is kind of >>> crazy though no matter what the syntax is. >>> >>> How about taking a completely different approach, inspired by the >>> -cpu arg and implement: >>> >>> -machine accel=3Dbest >> >> Something like that sounds like the best solution to me, but I'd maybe >> rather not call it "best", since the definition of "best" might depend >> on your use-case (e.g. do you want to use a CPU close to the host or >> something different which might be better emulated by TCG?). >=20 > Indeed - you may well want to do TCG on Aarch64 if you want to test new > instructions. >=20 >> >> What about "-accel any" or "-accel fastest" or something similar? >=20 > "any" is just ambiguous, "fastest" is just begging for me to find a > micro-benchmark that TCG outperforms on ;-) >=20 > "-accel default" could be considered to have vibes of Do The Right > Thing (tm) and could in time actually become so! "-accel default" sounds like the default behavior that you'd also get if you don't use this option at all ... what about "-accel auto" to say that QEMU should pick an accelerator automatically? Thomas