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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 4F842C27C4F for ; Tue, 18 Jun 2024 09:54:17 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1sJVXO-0003Wa-OD; Tue, 18 Jun 2024 05:54:02 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sJVXM-0003VX-Uc for qemu-devel@nongnu.org; Tue, 18 Jun 2024 05:54:00 -0400 Received: from mail-wm1-x32b.google.com ([2a00:1450:4864:20::32b]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1sJVXK-0007dX-Pu for qemu-devel@nongnu.org; Tue, 18 Jun 2024 05:54:00 -0400 Received: by mail-wm1-x32b.google.com with SMTP id 5b1f17b1804b1-42121d27861so41680865e9.0 for ; Tue, 18 Jun 2024 02:53:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1718704437; x=1719309237; darn=nongnu.org; h=content-transfer-encoding:mime-version:message-id:date:references :in-reply-to:subject:cc:to:from:from:to:cc:subject:date:message-id :reply-to; bh=gXF1PJ4Uha8/rBYPYkTY+qderDnntrtGPsFK0GwQRRc=; b=V6KgReMwjke9+DjRLlmLXgHgfUAPPUuZUS3eIlgxf534oJ98I1iT7Nbu7LvF/gRkcc v33o16FJZJHJSQ0JMtSylfZsTWNjiGDmrTv/t35ngMePeou5UL9RO9B/XchYi12iL2yF isHx7pvhsxn1COq+I8hXLbzO+1GknZM+kSykX+BOJdqc/Q5/SqN/mjH7nsMic/Z78qlU utodDbzjGVwkqHmqzFXgyzQaY5I/q7UguzMKlAkOkiUrJNMAcY/AiD16+ivx9Qw6EtnZ IuEWUK2Unn7FW+dqny/pgkEbAOUn1QgrXOIPthkbDclGB/15msvLHX5phtrmkYOSRn1j cJ2w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1718704437; x=1719309237; h=content-transfer-encoding:mime-version:message-id:date:references :in-reply-to:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=gXF1PJ4Uha8/rBYPYkTY+qderDnntrtGPsFK0GwQRRc=; b=wEttmDUNosYcHw1alUFYIr0oD0X9XFVPYSNo/LHTfElz8kRNshB0rzQ86feOGQlVGx awXLFYLGCS/0EVNZNarFjYQX4sx1V5WNcQdiyl7y1xpmYIASdHQuJcJEeWk1XwmnBu7G 2pHhzCgESEQSrQxODBDhs7PMy3fvC/rxxUJCnTMe5tOBolVJ78kO2S0pJd3kFJ1xLkjg gtQxq3jELBMJE9hN1mLjGC7nHcrrYlnZCwR7+3T+buUaO6PBXw80NPj3sJKctcmgnXRm lJ4j7EcpOqQICqf8PqN/Dj/K/ouTY4rbrStnsDFaHwLvSSTYaCduqQrSTiMdCjvd8/eu Vv1w== X-Forwarded-Encrypted: i=1; AJvYcCXq+w9Y7px26ln+xiGP0bOuD5nzmeBnB8DLHJ8P4ehMuGdNXpOPfPb7EgdmoEDRn/4qUeQHLVovn0q2Ij7oQs6qYqN4vXI= X-Gm-Message-State: AOJu0YwNkdfvpNmFBWlVct4tB2bgRCL5serQmJJ6Kr6PjV1ElYjULtCp Y158e+9yHTDav62ml9Ag05CzjoEZ6ReiUCuGc4qbcChgrS0vqghQCTpzhhatg4A= X-Google-Smtp-Source: AGHT+IFhlF3hgJqwNC1kT5uuSbB14ovBJTJLMfQeME31lq2xN12DFaRayAEeSgz/ORSGrVl6+zvRkA== X-Received: by 2002:a05:600c:4448:b0:421:819c:5d6b with SMTP id 5b1f17b1804b1-423048262c3mr89662145e9.23.1718704436656; Tue, 18 Jun 2024 02:53:56 -0700 (PDT) Received: from draig.lan ([85.9.250.243]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-36075104b74sm13696342f8f.107.2024.06.18.02.53.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 18 Jun 2024 02:53:56 -0700 (PDT) Received: from draig (localhost [IPv6:::1]) by draig.lan (Postfix) with ESMTP id 87BFA5F8AC; Tue, 18 Jun 2024 10:53:55 +0100 (BST) From: =?utf-8?Q?Alex_Benn=C3=A9e?= To: Pierrick Bouvier Cc: "Dr. David Alan Gilbert" , qemu-devel@nongnu.org, David Hildenbrand , Ilya Leoshkevich , Daniel Henrique Barboza , Marcelo Tosatti , Paolo Bonzini , Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= , Mark Burton , qemu-s390x@nongnu.org, Peter Maydell , kvm@vger.kernel.org, Laurent Vivier , Halil Pasic , Christian Borntraeger , Alexandre Iooss , qemu-arm@nongnu.org, Alexander Graf , Nicholas Piggin , Marco Liebel , Thomas Huth , Roman Bolshakov , qemu-ppc@nongnu.org, Mahmoud Mandour , Cameron Esfahani , Jamie Iles , Richard Henderson Subject: Re: [PATCH 9/9] contrib/plugins: add ips plugin example for cost modeling In-Reply-To: <4e5fded0-d1a9-4494-a66d-6488ce1bcb33@linaro.org> (Pierrick Bouvier's message of "Mon, 17 Jun 2024 15:29:56 -0700") References: <20240612153508.1532940-1-alex.bennee@linaro.org> <20240612153508.1532940-10-alex.bennee@linaro.org> <777e1b13-9a4f-4c32-9ff7-9cedf7417695@linaro.org> <616df287-a167-4a05-8f08-70a78a544929@linaro.org> <4e5fded0-d1a9-4494-a66d-6488ce1bcb33@linaro.org> Date: Tue, 18 Jun 2024 10:53:55 +0100 Message-ID: <874j9qefv0.fsf@draig.linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=2a00:1450:4864:20::32b; envelope-from=alex.bennee@linaro.org; helo=mail-wm1-x32b.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Pierrick Bouvier writes: > On 6/17/24 13:56, Dr. David Alan Gilbert wrote: >> * Pierrick Bouvier (pierrick.bouvier@linaro.org) wrote: >>> On 6/14/24 15:00, Dr. David Alan Gilbert wrote: >>>> * Pierrick Bouvier (pierrick.bouvier@linaro.org) wrote: >>>>> Hi Dave, >>>>> >>>>> On 6/12/24 14:02, Dr. David Alan Gilbert wrote: >>>>>> * Alex Benn=C3=A9e (alex.bennee@linaro.org) wrote: >>>>>>> From: Pierrick Bouvier >>>>>>> >>>>>>> This plugin uses the new time control interface to make decisions >>>>>>> about the state of time during the emulation. The algorithm is >>>>>>> currently very simple. The user specifies an ips rate which applies >>>>>>> per core. If the core runs ahead of its allocated execution time the >>>>>>> plugin sleeps for a bit to let real time catch up. Either way time = is >>>>>>> updated for the emulation as a function of total executed instructi= ons >>>>>>> with some adjustments for cores that idle. >>>>>> >>>>>> A few random thoughts: >>>>>> a) Are there any definitions of what a plugin that controls time >>>>>> should do with a live migration? >>>>> >>>>> It's not something that was considered as part of this work. >>>> >>>> That's OK, the only thing is we need to stop anyone from hitting probl= ems >>>> when they don't realise it's not been addressed. >>>> One way might be to add a migration blocker; see include/migration/blo= cker.h >>>> then you might print something like 'Migration not available due to pl= ugin ....' >>>> >>> >>> So basically, we could make a call to migrate_add_blocker(), when someo= ne >>> request time_control through plugin API? >>> >>> IMHO, it's something that should be part of plugin API (if any plugin c= alls >>> qemu_plugin_request_time_control()), instead of the plugin code itself.= This >>> way, any plugin getting time control automatically blocks any potential >>> migration. >> Note my question asked for a 'any definitions of what a plugin ..' - >> so >> you could define it that way, another one is to think that in the future >> you may allow it and the plugin somehow interacts with migration not to >> change time at certain migration phases. >>=20 > > I would be in favor to forbid usage for now in this context. I'm not > sure why people would play with migration and plugins generally at > this time (there might be experiments or use cases I'm not aware of), > so a simple barrier preventing that seems ok. > > This plugin is part of an experiment where we implement a qemu feature > (icount=3Dauto in this case) by using plugins. If it turns into a > successful usage and this plugin becomes popular, we can always lift > the limitation later. > > @Alex, would you like to add this now (icount=3Dauto is still not > removed from qemu), or wait for integration, and add this as another > patch? I think we follow the deprecation process so once integrated we post a deprecation notice in: https://qemu.readthedocs.io/en/master/about/deprecated.html and then remove it after a couple of releases. --=20 Alex Benn=C3=A9e Virtualisation Tech Lead @ Linaro