From: Peter Zijlstra <peterz@infradead.org>
To: "Liang, Kan" <kan.liang@linux.intel.com>
Cc: mingo@kernel.org, acme@redhat.com, linux-kernel@vger.kernel.org,
alexander.shishkin@linux.intel.com, jolsa@redhat.com,
eranian@google.com, namhyung@kernel.org, ak@linux.intel.com
Subject: Re: [PATCH 1/5] perf/x86/intel/uncore: Parse uncore discovery tables
Date: Tue, 16 Mar 2021 15:05:13 +0100 [thread overview]
Message-ID: <YFC7GeBzL70QX2fS@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <f6231c10-60b1-34ec-fb7e-103a6cd2dbcf@linux.intel.com>
On Tue, Mar 16, 2021 at 08:42:25AM -0400, Liang, Kan wrote:
>
>
> On 3/16/2021 7:43 AM, Peter Zijlstra wrote:
> > On Fri, Mar 12, 2021 at 08:34:34AM -0800, kan.liang@linux.intel.com wrote:
> > > From: Kan Liang <kan.liang@linux.intel.com>
> > >
> > > A self-describing mechanism for the uncore PerfMon hardware has been
> > > introduced with the latest Intel platforms. By reading through an MMIO
> > > page worth of information, perf can 'discover' all the standard uncore
> > > PerfMon registers in a machine.
> > >
> > > The discovery mechanism relies on BIOS's support. With a proper BIOS,
> > > a PCI device with the unique capability ID 0x23 can be found on each
> > > die. Perf can retrieve the information of all available uncore PerfMons
> > > from the device via MMIO. The information is composed of one global
> > > discovery table and several unit discovery tables.
> >
> > > If a BIOS doesn't support the 'discovery' mechanism, there is nothing
> > > changed.
> >
> > What if the BIOS got it wrong? Will the driver still get it correct if
> > it is a known platform?
>
> Yes, I will submit a platform specific patch to fix this case.
>
> >
> > Do we need a chicken flag to kill the discovery? uncore_no_discover?
> >
>
> Yes, I plan to introduce a .use_discovery_tables flag to indicate whether to
> use the discovery tables for the known platform.
>
> The below codes is part of the upcoming SPR uncore patches.
> The first SPR uncore patch will still rely on the BIOS discovery tables,
> because some uncore block information hasn't been published yet. We have to
> retrieve the information fro the tables. Once all the information is
> published, we can kill the discovery by removing the ".use_discovery_tables
> = true".
I was thinking of a module parameter, such that we can tell it to skip
discovery on module load time etc.
next prev parent reply other threads:[~2021-03-16 14:06 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-12 16:34 [PATCH 0/5] Uncore PMON discovery mechanism support kan.liang
2021-03-12 16:34 ` [PATCH 1/5] perf/x86/intel/uncore: Parse uncore discovery tables kan.liang
2021-03-16 11:40 ` Peter Zijlstra
2021-03-16 12:29 ` Liang, Kan
2021-03-16 11:43 ` Peter Zijlstra
2021-03-16 12:42 ` Liang, Kan
2021-03-16 14:05 ` Peter Zijlstra [this message]
2021-03-16 14:53 ` Liang, Kan
2021-03-12 16:34 ` [PATCH 2/5] perf/x86/intel/uncore: Generic support for the MSR type of uncore blocks kan.liang
2021-03-12 16:34 ` [PATCH 3/5] perf/x86/intel/uncore: Rename uncore_notifier to uncore_pci_sub_notifier kan.liang
2021-03-12 16:34 ` [PATCH 4/5] perf/x86/intel/uncore: Generic support for the PCI type of uncore blocks kan.liang
2021-03-12 16:34 ` [PATCH 5/5] perf/x86/intel/uncore: Generic support for the MMIO " kan.liang
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