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[213.175.37.10]) by smtp.gmail.com with ESMTPSA id h12-20020a05620a400c00b006b949afa980sm1229407qko.56.2022.11.11.02.54.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 11 Nov 2022 02:54:46 -0800 (PST) Date: Fri, 11 Nov 2022 11:54:43 +0100 From: Igor Mammedov To: Gavin Shan Cc: Markus Armbruster , Zhenyu Zhang , qemu-devel@nongnu.org, philmd@linaro.org, shan.gavin@gmail.com, eric.auger@redhat.com, lijin@redhat.com Subject: Re: [PATCH v3] qapi/qom: Memory backend property prealloc-threads doc fix Message-ID: <20221111115443.30eec762@imammedo.users.ipa.redhat.com> In-Reply-To: <98a4d569-b81e-b3e3-f011-82ef19eeb5df@redhat.com> References: <20221111030541.191186-1-zhenyzha@redhat.com> <87bkpedm2z.fsf@pond.sub.org> <20221111101310.47bdced9@imammedo.users.ipa.redhat.com> <98a4d569-b81e-b3e3-f011-82ef19eeb5df@redhat.com> X-Mailer: Claws Mail 4.1.0 (GTK 3.24.34; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=imammedo@redhat.com; helo=us-smtp-delivery-124.mimecast.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, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, 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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Fri, 11 Nov 2022 17:34:04 +0800 Gavin Shan wrote: > On 11/11/22 5:13 PM, Igor Mammedov wrote: > > On Fri, 11 Nov 2022 07:47:16 +0100 > > Markus Armbruster wrote: > >> Gavin Shan writes: > >>> On 11/11/22 11:05 AM, Zhenyu Zhang wrote: > >>>> Commit ffac16fab3 "hostmem: introduce "prealloc-threads" property" > >>>> (v5.0.0) changed the default number of threads from number of CPUs > >>>> to 1. This was deemed a regression, and fixed in commit f8d426a685 > >>>> "hostmem: default the amount of prealloc-threads to smp-cpus". > >>>> Except the documentation remained unchanged. Update it now. > >>>> Signed-off-by: Zhenyu Zhang > >>>> --- > >>>> v3: Covers historical descriptions (Markus) > >>>> v2: The property is changed to smp-cpus since 5.0 (Phild) > >>>> --- > >>>> qapi/qom.json | 2 +- > >>>> 1 file changed, 1 insertion(+), 1 deletion(-) > >>>> > >>> > >>> With the following comments addressed: > >>> > >>> Reviewed-by: Gavin Shan > >>> > >>> --- > >>> > >>> Please consider amending the commit log to something like below. > >>> > >>> The default "prealloc-threads" value is set to 1 when the property is > >>> added by commit ffac16fab33b ("hostmem: introduce "prealloc-threads" > >>> property") in v5.0.0. The default value is conflicting with the sugar > >>> property as the value provided by the sugar property is number of CPUs. > >> > >> What is the sugar property? Can you explain the conflict in a bit more > >> detail? > > > > my guess is that Gavin means mem_prealloc compat glue in qemu_process_sugar_options() > > > > property value should be set according to following order > > default -> compat -> explicit value > > so I don't see any conflict here. > > > > PS: > > if it we up to me, default would have stayed 1, > > and prealloc-threads fixup to vCPUs number would happen in vl.c > > similar to what is done in qemu_process_sugar_options(), > > keeping backend clean of external dependencies. > > > > Yes, it's the sugar property I was talking about. I'm not sure if > we have a more popular name for this property: compat property or > sugar property. > > When 'mem-prealloc=on' and 'prealloc-threads=xxx' aren't provided, > the value is 1 before commit f8d426a6852c is applied. It's not > inconsistent with 'mem-prealloc=on'. It's the conflict I was talking > about and it's fixed by commit f8d426a6852c default was not supposed to be consistent with legacy mem-prealloc and sugar property takes care of mem-prealloc=on case. so commit message in its current form looks fine to me. > >> > >>> The conflict has been fixed by commit f8d426a6852c ("hostmem: default > >>> the amount of prealloc-threads to smp-cpus"). However, 'qapi/qom.json' > >>> was missed to be updated accordingly in the commit. > >>> > >>> Update 'qapi/qom.json' to reflect the change in commit f8d426a6852c. > >>> > >>> Signed-off-by: Zhenyu Zhang > >>> > >>> When a specific commit is mentioned in the commit log, we usually have > >>> fixed format like below. > >>> > >>> commit ffac16fab33b ("hostmem: introduce "prealloc-threads" property") > >>> commit f8d426a6852c ("hostmem: default the amount of prealloc-threads to smp-cpus") > >> > >> This is certainly a common format, but the other one is also in use. > >> > >>>> diff --git a/qapi/qom.json b/qapi/qom.json > >>>> index 30e76653ad..dfd89bc6d4 100644 > >>>> --- a/qapi/qom.json > >>>> +++ b/qapi/qom.json > >>>> @@ -576,7 +576,7 @@ > >>>> # > >>>> # @prealloc: if true, preallocate memory (default: false) > >>>> # > >>>> -# @prealloc-threads: number of CPU threads to use for prealloc (default: 1) > >>>> +# @prealloc-threads: number of CPU threads to use for prealloc (default: number of CPUs) (since 5.0) > >>>> # > >>>> # @prealloc-context: thread context to use for creation of preallocation threads > >>>> # (default: none) (since 7.2) > >>>> > >>> > >>> The line seems exceeding 80 characters. It'd better to limit each line in 75 characters. > >>> So you probably need: > >>> > >>> # @prealloc-threads: number of CPU threads to use for prealloc (default: number of CPUs) > >>> # (since 5.0) > >> > >> Still exceeds :) > >> > >> I suggested > >> > >> # @prealloc-threads: number of CPU threads to use for prealloc > >> # (default: number of CPUs) (since 5.0) > >> > > > > Markus's suggestion works :) > > Thanks, > Gavin > >