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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, 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 2F3C2C33C8C for ; Tue, 7 Jan 2020 14:27:58 +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 EF351222D9 for ; Tue, 7 Jan 2020 14:27:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="JMKi012S" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EF351222D9 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]:49776 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ioppt-0006u7-4m for qemu-devel@archiver.kernel.org; Tue, 07 Jan 2020 09:27:57 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:37531) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iopoU-0005Jd-DQ for qemu-devel@nongnu.org; Tue, 07 Jan 2020 09:26:33 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iopoS-0004j8-Fl for qemu-devel@nongnu.org; Tue, 07 Jan 2020 09:26:29 -0500 Received: from us-smtp-2.mimecast.com ([207.211.31.81]:44549 helo=us-smtp-delivery-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iopoP-0004g5-Td for qemu-devel@nongnu.org; Tue, 07 Jan 2020 09:26:28 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1578407183; h=from:from:reply-to: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; bh=VVV/ibB7PnpiklHu6m3mhkl7dn6XgtXp6kCDjzOkSiE=; b=JMKi012SPPQdtFGwzElHsljCpU+HDQW347wfS9FCRhITMk2lJfI8xhUgp5dBhLwfXs2qTN EqPAub3umisJGlq41qxMCSVvknaGfAfQWaFpsSr4WQ3hhn11sgQHgdifqRBXkJHK6HlcBw adrmV+68IgIXnj2rCGAiU4PEvc5K0JA= 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-263-LOMhTOSbNUuUZPd2NV86hQ-1; Tue, 07 Jan 2020 09:26:22 -0500 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 0CAA6800D53; Tue, 7 Jan 2020 14:26:21 +0000 (UTC) Received: from redhat.com (ovpn-112-61.ams2.redhat.com [10.36.112.61]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 98EE17BFFA; Tue, 7 Jan 2020 14:26:12 +0000 (UTC) Date: Tue, 7 Jan 2020 14:26:09 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Thomas Huth Subject: Re: Priority of -accel (was: [PATCH] tests/qemu-iotests: Update tests to recent desugarized -accel option) Message-ID: <20200107142609.GB3368802@redhat.com> 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> MIME-Version: 1.0 In-Reply-To: <3241dff4-6223-404f-55d4-846991763046@redhat.com> User-Agent: Mutt/1.12.1 (2019-06-15) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-MC-Unique: LOMhTOSbNUuUZPd2NV86hQ-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 207.211.31.81 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: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: Kevin Wolf , qemu-block@nongnu.org, Markus Armbruster , Wainer dos Santos Moschetta , qemu-devel@nongnu.org, Paolo Bonzini , Max Reitz , Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Tue, Jan 07, 2020 at 03:14:52PM +0100, Thomas Huth wrote: > 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... > >=20 > > 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. > >=20 > > How about taking a completely different approach, inspired by the > > -cpu arg and implement: > >=20 > > -machine accel=3Dbest >=20 > 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?). > > What about "-accel any" or "-accel fastest" or something similar? If there are many HW virt accelerators on a host, "fastest" might not be what we optimize for - we might prefer the more feature complete one even if theoeretically slower. I suggested "best" as it intentionally somewhat vague about what particular criteria it optimizes for. I would document it as "best: attempt to use a hardware virt accelerator for this platform. Falls back to emulation if none is available for use." Utimately though this is just bikeshedding & I don't care much about the specific name choice, just the general concept. Regards, Daniel --=20 |: https://berrange.com -o- https://www.flickr.com/photos/dberrange= :| |: https://libvirt.org -o- https://fstop138.berrange.com= :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange= :|