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From: "Song Bao Hua (Barry Song)" <song.bao.hua@hisilicon.com>
To: Greg KH <gregkh@linuxfoundation.org>
Cc: "tim.c.chen@linux.intel.com" <tim.c.chen@linux.intel.com>,
	"catalin.marinas@arm.com" <catalin.marinas@arm.com>,
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	Jonathan Cameron <jonathan.cameron@huawei.com>,
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	"Zengtao (B)" <prime.zeng@hisilicon.com>,
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	"hpa@zytor.com" <hpa@zytor.com>
Subject: RE: [RFC PATCH v5 1/4] topology: Represent clusters of CPUs within a die
Date: Fri, 19 Mar 2021 06:57:08 +0000
Message-ID: <eb48302277f3436eb9899032e6b0bf1c@hisilicon.com> (raw)
In-Reply-To: <YFRGIedW1fUlnmi+@kroah.com>



> -----Original Message-----
> From: Greg KH [mailto:gregkh@linuxfoundation.org]
> Sent: Friday, March 19, 2021 7:35 PM
> To: Song Bao Hua (Barry Song) <song.bao.hua@hisilicon.com>
> Cc: tim.c.chen@linux.intel.com; catalin.marinas@arm.com; will@kernel.org;
> rjw@rjwysocki.net; vincent.guittot@linaro.org; bp@alien8.de;
> tglx@linutronix.de; mingo@redhat.com; lenb@kernel.org; peterz@infradead.org;
> dietmar.eggemann@arm.com; rostedt@goodmis.org; bsegall@google.com;
> mgorman@suse.de; msys.mizuma@gmail.com; valentin.schneider@arm.com; Jonathan
> Cameron <jonathan.cameron@huawei.com>; juri.lelli@redhat.com;
> mark.rutland@arm.com; sudeep.holla@arm.com; aubrey.li@linux.intel.com;
> linux-arm-kernel@lists.infradead.org; linux-kernel@vger.kernel.org;
> linux-acpi@vger.kernel.org; x86@kernel.org; xuwei (O) <xuwei5@huawei.com>;
> Zengtao (B) <prime.zeng@hisilicon.com>; guodong.xu@linaro.org; yangyicong
> <yangyicong@huawei.com>; Liguozhu (Kenneth) <liguozhu@hisilicon.com>;
> linuxarm@openeuler.org; hpa@zytor.com
> Subject: Re: [RFC PATCH v5 1/4] topology: Represent clusters of CPUs within
> a die
> 
> On Fri, Mar 19, 2021 at 05:16:15PM +1300, Barry Song wrote:
> > diff --git a/Documentation/admin-guide/cputopology.rst
> b/Documentation/admin-guide/cputopology.rst
> > index b90dafc..f9d3745 100644
> > --- a/Documentation/admin-guide/cputopology.rst
> > +++ b/Documentation/admin-guide/cputopology.rst
> > @@ -24,6 +24,12 @@ core_id:
> >  	identifier (rather than the kernel's).  The actual value is
> >  	architecture and platform dependent.
> >
> > +cluster_id:
> > +
> > +	the Cluster ID of cpuX.  Typically it is the hardware platform's
> > +	identifier (rather than the kernel's).  The actual value is
> > +	architecture and platform dependent.
> > +
> >  book_id:
> >
> >  	the book ID of cpuX. Typically it is the hardware platform's
> > @@ -56,6 +62,14 @@ package_cpus_list:
> >  	human-readable list of CPUs sharing the same physical_package_id.
> >  	(deprecated name: "core_siblings_list")
> >
> > +cluster_cpus:
> > +
> > +	internal kernel map of CPUs within the same cluster.
> > +
> > +cluster_cpus_list:
> > +
> > +	human-readable list of CPUs within the same cluster.
> > +
> >  die_cpus:
> >
> >  	internal kernel map of CPUs within the same die.
> 
> Why are these sysfs files in this file, and not in a Documentation/ABI/
> file which can be correctly parsed and shown to userspace?

Well. Those ABIs have been there for much a long time. It is like:

[root@ceph1 topology]# ls
core_id  core_siblings  core_siblings_list  physical_package_id thread_siblings  thread_siblings_list
[root@ceph1 topology]# pwd
/sys/devices/system/cpu/cpu100/topology
[root@ceph1 topology]# cat core_siblings_list
64-127
[root@ceph1 topology]#

> 
> Any chance you can fix that up here as well?

Yes. we will send a separate patch to address this, which won't
be in this patchset. This patchset will base on that one.

> 
> Also note that "list" is not something that goes in sysfs, sysfs is "one
> value per file", and a list is not "one value".  How do you prevent
> overflowing the buffer of the sysfs file if you have a "list"?
> 

At a glance, the list is using "-" rather than a real list
[root@ceph1 topology]# cat core_siblings_list
64-127

Anyway, I will take a look if it has any chance to overflow.

> thanks,
> 
> greg k-h

Thanks
Barry


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Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-19  4:16 [RFC PATCH v5 0/4] scheduler: expose the topology of clusters and add cluster scheduler Barry Song
2021-03-19  4:16 ` [RFC PATCH v5 1/4] topology: Represent clusters of CPUs within a die Barry Song
2021-03-19  6:35   ` Greg KH
2021-03-19  6:57     ` Song Bao Hua (Barry Song) [this message]
2021-03-19  9:36       ` Jonathan Cameron
2021-03-19 10:01         ` Greg KH
2021-04-20  3:30           ` Song Bao Hua (Barry Song)
2021-04-21  4:06           ` Song Bao Hua (Barry Song)
2021-03-19  4:16 ` [RFC PATCH v5 2/4] scheduler: add scheduler level for clusters Barry Song
2021-03-19  4:16 ` [RFC PATCH v5 3/4] scheduler: scan idle cpu in cluster before scanning the whole llc Barry Song
2021-03-19 21:39   ` Song Bao Hua (Barry Song)
2021-03-19  4:16 ` [RFC PATCH v5 4/4] scheduler: Add cluster scheduler level for x86 Barry Song
2021-03-23 22:50   ` Tim Chen
2021-03-23 23:21     ` Song Bao Hua (Barry Song)
2021-04-20 18:31       ` Tim Chen
2021-04-20 22:31         ` Song Bao Hua (Barry Song)
2021-03-31 10:07     ` Song Bao Hua (Barry Song)

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