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 B0760C433EF for ; Fri, 26 Nov 2021 07:04:58 +0000 (UTC) Received: from localhost ([::1]:34036 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mqVI1-0005nT-FH for qemu-devel@archiver.kernel.org; Fri, 26 Nov 2021 02:04:57 -0500 Received: from eggs.gnu.org ([209.51.188.92]:56110) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mqVH1-00058l-20 for qemu-devel@nongnu.org; Fri, 26 Nov 2021 02:03:55 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:22247) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mqVGx-0001Wj-Gu for qemu-devel@nongnu.org; Fri, 26 Nov 2021 02:03:53 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1637910230; 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; bh=00QKBZEjXLC39T4MU86KnwMehT2dQkhH4//03VpbCYM=; b=hLnChQVk/VhA+pC5zobXjuz9/Bnsc8820/nko7cr65d3AlnNT52Ov5CQ48AQUVaRbDnupL BwaqzuGBU9D98qlmNOhq5TeVegCikuel2icnTXhyIivZv+OSoVJETuIuhicVD2m8Ma4hmN SWIXbwPwXpeJtsp2t+B73KtW6iv74Sc= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-572-XexZy2AvM_-XEnSLBNtO6A-1; Fri, 26 Nov 2021 02:03:48 -0500 X-MC-Unique: XexZy2AvM_-XEnSLBNtO6A-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id F40EB81CCB4; Fri, 26 Nov 2021 07:03:45 +0000 (UTC) Received: from blackfin.pond.sub.org (ovpn-112-7.ams2.redhat.com [10.36.112.7]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 7AAD960C7F; Fri, 26 Nov 2021 07:03:44 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 2F36A11380A7; Fri, 26 Nov 2021 08:03:43 +0100 (CET) From: Markus Armbruster To: huangy81@chinatelecom.cn Subject: Re: [PATCH v6 3/3] cpus-common: implement dirty page limit on vCPU References: <91286fcfc24795385fe4df0d69a48c34f8eac942.1637857372.git.huangy81@chinatelecom.cn> Date: Fri, 26 Nov 2021 08:03:43 +0100 In-Reply-To: <91286fcfc24795385fe4df0d69a48c34f8eac942.1637857372.git.huangy81@chinatelecom.cn> (huangy's message of "Fri, 26 Nov 2021 00:27:52 +0800") Message-ID: <87tufzbdps.fsf@dusky.pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=armbru@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=170.10.133.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.702, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 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: , Cc: Juan Quintela , David Hildenbrand , Richard Henderson , qemu-devel , Peter Xu , "Dr. David Alan Gilbert" , Paolo Bonzini , Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" huangy81@chinatelecom.cn writes: > From: Hyman Huang(=E9=BB=84=E5=8B=87) > > Implement dirtyrate calculation periodically basing on > dirty-ring and throttle vCPU until it reachs the quota > dirty page rate given by user. > > Introduce qmp commands set-dirty-limit/cancel-dirty-limit to > set/cancel dirty page limit on vCPU. > > Signed-off-by: Hyman Huang(=E9=BB=84=E5=8B=87) > --- > cpus-common.c | 41 +++++++++++++++++++++++++++++++++++++++++ > include/hw/core/cpu.h | 9 +++++++++ > qapi/migration.json | 47 +++++++++++++++++++++++++++++++++++++++++++++= ++ > softmmu/vl.c | 1 + > 4 files changed, 98 insertions(+) > > diff --git a/cpus-common.c b/cpus-common.c > index 6e73d3e..3c156b3 100644 > --- a/cpus-common.c > +++ b/cpus-common.c > @@ -23,6 +23,11 @@ > #include "hw/core/cpu.h" > #include "sysemu/cpus.h" > #include "qemu/lockable.h" > +#include "sysemu/dirtylimit.h" > +#include "sysemu/cpu-throttle.h" > +#include "sysemu/kvm.h" > +#include "qapi/error.h" > +#include "qapi/qapi-commands-migration.h" > =20 > static QemuMutex qemu_cpu_list_lock; > static QemuCond exclusive_cond; > @@ -352,3 +357,39 @@ void process_queued_cpu_work(CPUState *cpu) > qemu_mutex_unlock(&cpu->work_mutex); > qemu_cond_broadcast(&qemu_work_cond); > } > + > +void qmp_set_dirty_limit(int64_t idx, > + uint64_t dirtyrate, > + Error **errp) > +{ > + if (!kvm_enabled() || !kvm_dirty_ring_enabled()) { > + error_setg(errp, "setting a dirty page limit requires support fr= om dirty ring"); Can we phrase the message in a way that gives the user a chance to guess what he needs to do to avoid it? Perhaps: "setting a dirty page limit requires KVM with accelerator property 'dirty-ring-size' set". > + return; > + } > + > + dirtylimit_calc(); > + dirtylimit_vcpu(idx, dirtyrate); > +} > + > +void qmp_cancel_dirty_limit(int64_t idx, > + Error **errp) > +{ Three cases: Case 1: enable is impossible, so nothing to do. Case 2: enable is possible and we actually enabled. Case 3: enable is possible, but we didn't. Nothing to do. > + if (!kvm_enabled() || !kvm_dirty_ring_enabled()) { > + error_setg(errp, "no need to cancel a dirty page limit as dirty = ring not enabled"); > + return; This is case 1. We error out. > + } > + > + if (unlikely(!dirtylimit_cancel_vcpu(idx))) { I don't think unlikely() matters here. > + dirtylimit_calc_quit(); > + } In case 2, dirtylimit_calc_quit() returns zero if this was the last limit, else non-zero. If the former, we request the thread to stop. In case 3, dirtylimit_calc_quit() returns zero, and we do nothing. Why is case 1 and error, but case 3 isn't? Both could silently do nothing, like case 3 does now. Both could error out, like case 1 does now. A possible common error message: "there is no dirty page limit to cancel". I'd be okay with consistently doing nothing, and with consistently erroring out. > +} > + > +void dirtylimit_setup(int max_cpus) > +{ > + if (!kvm_enabled() || !kvm_dirty_ring_enabled()) { > + return; > + } > + > + dirtylimit_calc_state_init(max_cpus); > + dirtylimit_state_init(max_cpus); > +} > diff --git a/include/hw/core/cpu.h b/include/hw/core/cpu.h > index e948e81..11df012 100644 > --- a/include/hw/core/cpu.h > +++ b/include/hw/core/cpu.h > @@ -881,6 +881,15 @@ void end_exclusive(void); > */ > void qemu_init_vcpu(CPUState *cpu); > =20 > +/** > + * dirtylimit_setup: > + * > + * Initializes the global state of dirtylimit calculation and > + * dirtylimit itself. This is prepared for vCPU dirtylimit which > + * could be triggered during vm lifecycle. > + */ > +void dirtylimit_setup(int max_cpus); > + > #define SSTEP_ENABLE 0x1 /* Enable simulated HW single stepping */ > #define SSTEP_NOIRQ 0x2 /* Do not use IRQ while single stepping */ > #define SSTEP_NOTIMER 0x4 /* Do not Timers while single stepping */ > diff --git a/qapi/migration.json b/qapi/migration.json > index bbfd48c..2b0fe19 100644 > --- a/qapi/migration.json > +++ b/qapi/migration.json > @@ -1850,6 +1850,53 @@ > { 'command': 'query-dirty-rate', 'returns': 'DirtyRateInfo' } > =20 > ## > +# @set-dirty-limit: > +# > +# Set the upper limit of dirty page rate for a vCPU. > +# > +# This command could be used to cap the vCPU memory load, which is also "Could be used" suggests there are other uses. I don't think there are. > +# refered as "dirty page rate". Users can use set-dirty-limit unconditio= nally, > +# but if one want to know which vCPU is in high memory load and which vC= PU "one wants" > +# should be limited, using calc-dirty-rate command with dirty-ring mode = maybe "may be" > +# an availiable method. Note that this command requires support from dir= ty "available". Consider using a spell checker. > +# ring, which means property "dirty-ring-size" of accelerator object "kv= m" > +# must be set. Please limit doc comment line length to approximately 70 characters for legibility. Here's my try: ## # @set-dirty-limit: # # Set the upper limit of dirty page rate for a virtual CPU. # # Requires KVM with accelerator property "dirty-ring-size" set. # A virtual CPU's dirty page rate is a measure of its memory load. # To observe dirty page rates, use @calc-dirty-rate. > +# > +# @cpu-index: vCPU index to set dirty page limit. I'd go with # @cpu-index: index of the virtual CPU. > +# > +# @dirty-rate: upper limit for the specified vCPU's dirty page rate (MB/= s) > +# > +# Since: 7.0 > +# > +# Example: > +# {"execute": "set-dirty-limit"} > +# "arguments": { "cpu-index": 0, > +# "dirty-rate": 200 } } > +# > +## > +{ 'command': 'set-dirty-limit', > + 'data': { 'cpu-index': 'int', 'dirty-rate': 'uint64' } } > + > +## > +# @cancel-dirty-limit: > +# > +# Cancel the dirty page limit for the vCPU which has been set with > +# set-dirty-limit command. Note that this command requires support from > +# dirty ring, same as the "set-dirty-limit" command. > +# > +# @cpu-index: vCPU index to cancel the dirty page limit > +# > +# Since: 7.0 > +# > +# Example: > +# {"execute": "cancel-dirty-limit"} > +# "arguments": { "cpu-index": 0 } } > +# > +## > +{ 'command': 'cancel-dirty-limit', > + 'data': { 'cpu-index': 'int' } } > + > +## > # @snapshot-save: > # > # Save a VM snapshot > diff --git a/softmmu/vl.c b/softmmu/vl.c > index 620a1f1..0f83ce3 100644 > --- a/softmmu/vl.c > +++ b/softmmu/vl.c > @@ -3777,5 +3777,6 @@ void qemu_init(int argc, char **argv, char **envp) > qemu_init_displays(); > accel_setup_post(current_machine); > os_setup_post(); > + dirtylimit_setup(current_machine->smp.max_cpus); > resume_mux_open(); > }