From: Sandipan Das <sandipan.das@amd.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org,
x86@kernel.org, peterz@infradead.org, mingo@redhat.com,
acme@kernel.org, mark.rutland@arm.com,
alexander.shishkin@linux.intel.com, jolsa@kernel.org,
namhyung@kernel.org, irogers@google.com, adrian.hunter@intel.com,
bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com,
eranian@google.com, ananth.narayan@amd.com,
ravi.bangoria@amd.com, santosh.shukla@amd.com
Subject: Re: [PATCH 3/6] x86/cpuid: Add smp helper
Date: Wed, 19 Jul 2023 17:29:55 +0530 [thread overview]
Message-ID: <3273e3fa-52a7-ab23-b64f-217cc410915f@amd.com> (raw)
In-Reply-To: <87mszsw25c.ffs@tglx>
On 7/19/2023 5:20 PM, Thomas Gleixner wrote:
> On Wed, Jul 19 2023 at 09:29, Thomas Gleixner wrote:
>> On Wed, Jul 19 2023 at 12:25, Sandipan Das wrote:
>>> Depending on which CPU the CPUID instruction is executed, some leaves
>>> can report different values. There are cases where it may be required
>>> to know all possible values.
>>> Add a new helper that executes CPUID on a particular CPU and returns
>>> the EAX, EBX, ECX and EDX values.
>>
>> NAK.
>>
>> This madness has to stop. The correct thing is to parse the information
>> in CPUID at the point where the CPU comes online and store it for easy
>> consumption.
>>
>> I'm in the process of reworking the CPUID and topology evaluation and
>> that's where these things need to be stored. I'm still fighting some
>> nightmares with the already existing mess.
>>
>> Look at the mess people created over time here:
>>
>> https://lore.kernel.org/lkml/20230717223049.327865981@linutronix.de
>>
>> No need to add more insanities to it. IOW, this has to wait for a week
>> or two until I settled the remaining issues.
>
> Actually you can do that today already. Either make it part of the CPUID
> evaluation or use the perf hotplug callback mechanism which is invoked
> early on the upcoming CPU and read that CPUID leaf.
>
Thanks for the suggestions. I'll start with the hotplug callback mechanism.
- Sandipan
next prev parent reply other threads:[~2023-07-19 12:00 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-19 6:55 [PATCH 0/6] perf/x86/amd: Add memory controller events Sandipan Das
2023-07-19 6:55 ` [PATCH 1/6] perf/x86/amd/uncore: Refactor uncore management Sandipan Das
2023-07-19 6:55 ` [PATCH 2/6] perf/x86/amd/uncore: Use rdmsr if rdpmc is unavailable Sandipan Das
2023-07-19 6:55 ` [PATCH 3/6] x86/cpuid: Add smp helper Sandipan Das
2023-07-19 7:28 ` Peter Zijlstra
2023-07-19 7:37 ` Sandipan Das
2023-07-19 7:29 ` Thomas Gleixner
2023-07-19 7:35 ` Sandipan Das
2023-07-19 11:50 ` Thomas Gleixner
2023-07-19 11:59 ` Sandipan Das [this message]
2023-07-19 6:55 ` [PATCH 4/6] perf/x86/amd/uncore: Add group exclusivity Sandipan Das
2023-07-19 6:55 ` [PATCH 5/6] perf/x86/amd/uncore: Add memory controller support Sandipan Das
2023-07-19 6:55 ` [PATCH 6/6] perf vendor events amd: Add Zen 4 memory controller events Sandipan Das
2023-07-19 16:12 ` Ian Rogers
2023-07-20 5:23 ` Sandipan Das
2023-07-20 15:50 ` Ian Rogers
2023-07-21 5:15 ` Sandipan Das
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=3273e3fa-52a7-ab23-b64f-217cc410915f@amd.com \
--to=sandipan.das@amd.com \
--cc=acme@kernel.org \
--cc=adrian.hunter@intel.com \
--cc=alexander.shishkin@linux.intel.com \
--cc=ananth.narayan@amd.com \
--cc=bp@alien8.de \
--cc=dave.hansen@linux.intel.com \
--cc=eranian@google.com \
--cc=hpa@zytor.com \
--cc=irogers@google.com \
--cc=jolsa@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-perf-users@vger.kernel.org \
--cc=mark.rutland@arm.com \
--cc=mingo@redhat.com \
--cc=namhyung@kernel.org \
--cc=peterz@infradead.org \
--cc=ravi.bangoria@amd.com \
--cc=santosh.shukla@amd.com \
--cc=tglx@linutronix.de \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).