From: "wangyanan (Y)" <email@example.com> To: "Andrew Jones" <firstname.lastname@example.org>, "Daniel P. Berrangé" <email@example.com> Cc: Barry Song <firstname.lastname@example.org>, Peter Maydell <email@example.com>, "Michael S . Tsirkin" <firstname.lastname@example.org>, email@example.com, firstname.lastname@example.org, email@example.com, Shannon Zhao <firstname.lastname@example.org>, email@example.com, Alistair Francis <firstname.lastname@example.org>, email@example.com, Paolo Bonzini <firstname.lastname@example.org>, email@example.com, Igor Mammedov <firstname.lastname@example.org>, email@example.com, David Gibson <firstname.lastname@example.org> Subject: Re: [RFC PATCH v4 0/7] hw/arm/virt: Introduce cpu topology support Date: Tue, 22 Jun 2021 20:31:22 +0800 [thread overview] Message-ID: <email@example.com> (raw) In-Reply-To: <20210622114634.crjqusw6x6oj4j6v@gator> On 2021/6/22 19:46, Andrew Jones wrote: > On Tue, Jun 22, 2021 at 11:18:09AM +0100, Daniel P. Berrangé wrote: >> On Tue, Jun 22, 2021 at 05:34:06PM +0800, Yanan Wang wrote: >>> Hi, >>> >>> This is v4 of the series  that I posted to introduce support for >>> generating cpu topology descriptions to guest. Comments are welcome! >>> >>> Description: >>> Once the view of an accurate virtual cpu topology is provided to guest, >>> with a well-designed vCPU pinning to the pCPU we may get a huge benefit, >>> e.g., the scheduling performance improvement. See Dario Faggioli's >>> research and the related performance tests in  for reference. So here >>> we go, this patch series introduces cpu topology support for ARM platform. >>> >>> In this series, instead of quietly enforcing the support for the latest >>> machine type, a new parameter "expose=on|off" in -smp command line is >>> introduced to leave QEMU users a choice to decide whether to enable the >>> feature or not. This will allow the feature to work on different machine >>> types and also ideally compat with already in-use -smp command lines. >>> Also we make much stricter requirement for the topology configuration >>> with "expose=on". >> Seeing this 'expose=on' parameter feels to me like we're adding a >> "make-it-work=yes" parameter. IMHO this is just something that should >> be done by default for the current machine type version and beyond. >> I don't see the need for a parameter to turnthis on, especially since >> it is being made architecture specific. >> > I agree. > > Yanan, we never discussed an "expose" parameter in the previous versions > of this series. We discussed a "strict" parameter though, which would > allow existing command lines to "work" using assumptions of what the user > meant and strict=on users to get what they mean or an error saying that > they asked for something that won't work or would require unreasonable > assumptions. Why was this changed to an "expose" parameter? Yes, we indeed discuss a new "strict" parameter but not a "expose" in v2  of this series.  https://firstname.lastname@example.org/ And in the discussion, we hoped things would work like below with "strict" parameter: Users who want to describe cpu topology should provide cmdline like -smp strict=on,cpus=4,sockets=2,cores=2,threads=1 and in this case we require an more accurate -smp configuration and then generate the cpu topology description through ACPI/DT. While without a strict description, no cpu topology description would be generated, so they get nothing through ACPI/DT. It seems to me that the "strict" parameter actually serves as a knob to turn on/off the exposure of topology, and this is the reason I changed the name. Thanks, Yanan . > Thanks, > drew > > .
next prev parent reply other threads:[~2021-06-22 12:33 UTC|newest] Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-06-22 9:34 Yanan Wang 2021-06-22 9:34 ` [RFC PATCH v4 1/7] vl: Add expose=on|off option support in -smp command line Yanan Wang 2021-06-22 9:34 ` [RFC PATCH v4 2/7] hw/arm/virt: Add separate -smp parsing function for ARM machines Yanan Wang 2021-06-22 9:34 ` [RFC PATCH v4 3/7] machine: disallow -smp expose=on for non-ARM machines Yanan Wang 2021-06-22 9:34 ` [RFC PATCH v4 4/7] device_tree: Add qemu_fdt_add_path Yanan Wang 2021-06-22 9:34 ` [RFC PATCH v4 5/7] hw/arm/virt: Add cpu-map to device tree Yanan Wang 2021-06-22 9:34 ` [RFC PATCH v4 6/7] hw/acpi/aml-build: Add Processor hierarchy node structure Yanan Wang 2021-06-22 9:34 ` [RFC PATCH v4 7/7] hw/acpi/aml-build: Generate PPTT table Yanan Wang 2021-06-22 10:18 ` [RFC PATCH v4 0/7] hw/arm/virt: Introduce cpu topology support Daniel P. Berrangé 2021-06-22 11:46 ` Andrew Jones 2021-06-22 12:31 ` wangyanan (Y) [this message] 2021-06-22 12:41 ` Daniel P. Berrangé 2021-06-22 14:04 ` wangyanan (Y) 2021-06-22 14:10 ` Daniel P. Berrangé 2021-06-22 14:15 ` Peter Maydell 2021-06-22 14:28 ` Daniel P. Berrangé 2021-06-28 11:14 ` wangyanan (Y) 2021-06-28 11:31 ` Daniel P. Berrangé 2021-06-28 11:53 ` wangyanan (Y) 2021-06-22 14:29 ` Andrew Jones 2021-06-22 15:15 ` Daniel P. Berrangé 2021-06-22 15:40 ` Igor Mammedov 2021-06-22 17:08 ` Andrew Jones 2021-06-22 17:14 ` Daniel P. Berrangé 2021-06-22 17:29 ` Andrew Jones 2021-06-22 17:39 ` Daniel P. Berrangé 2021-06-28 8:43 ` wangyanan (Y) 2021-06-28 8:58 ` Andrew Jones 2021-06-28 10:48 ` wangyanan (Y) 2021-06-30 6:36 ` wangyanan (Y) 2021-06-30 8:30 ` Andrew Jones 2021-06-30 9:37 ` wangyanan (Y) 2021-06-30 11:56 ` Andrew Jones 2021-07-01 6:15 ` wangyanan (Y)
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