linux-kernel - RE: [PATCH V2 0/2] measure SMI cost (user)

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Message-ID: <37D7C6CF3E00A74B8858931C1DB2F0775370F863@SHSMSX103.ccr.corp.intel.com>
Date:   Tue, 20 Jun 2017 13:43:56 +0000
From:   "Liang, Kan" <kan.liang@...el.com>
To:     "Jiri Olsa (jolsa@...nel.org)" <jolsa@...nel.org>,
        "'Arnaldo Carvalho de Melo'" <acme@...nel.org>
CC:     'Jiri Olsa' <jolsa@...hat.com>,
        'Peter Zijlstra' <peterz@...radead.org>,
        'Thomas Gleixner' <tglx@...utronix.de>,
        'Ingo Molnar' <mingo@...nel.org>,
        "'linux-kernel@...r.kernel.org'" <linux-kernel@...r.kernel.org>,
        "'Stephane Eranian'" <eranian@...gle.com>,
        'Jiri Olsa' <jolsa@...nel.org>,
        "'elliott@....com'" <elliott@....com>,
        'Andi Kleen' <andi@...stfloor.org>
Subject: RE: [PATCH V2 0/2] measure SMI cost (user)

Hi Arnaldo and Jirka,

Ping.
Any comments for the patch?

Thanks,
Kan 

> Subject: RE: [PATCH V2 0/2] measure SMI cost (user)
> 
> Hi Jirka,
> 
> Have you got a chance to try the code?
> Are you OK with the patch?
> 
> Thanks,
> Kan
> 
> >
> > Em Fri, Jun 02, 2017 at 03:45:11PM +0000, Liang, Kan escreveu:
> > > > > On Mon, May 29, 2017 at 02:52:39PM +0200, Peter Zijlstra wrote:
> > > > > > On Mon, May 29, 2017 at 02:46:37PM +0200, Jiri Olsa wrote:
> > > > > > > for some reason I can't get single SMI count generated, is
> > > > > > > there a setup/bench that would provoke that?
> >
> > > > > > Not having SMIs is a good thing ;-) Not sure we can tickle
> > > > > > them in a reliable way.
> >
> > > > > yea I saw some counts last time, now just zero so I was
> > > > > wondering if it's working
> >
> > > > We have internal test case which can generate SMI, but I cannot
> > > > publish the test case. Sorry about that.
> >
> > > APM_CNT (0xB2) could be used to trigger SMI#.
> >
> > Here if I run the following 'perf stat' command and press the mute
> > button (the one sharing F1 in a thinkpad t450s it triggers SMIs,
> > toggle it in quick sucession and it generates more, etc:
> >
> > [root@...et ~]# perf stat -I 1000 -e msr/smi/
> > #           time             counts unit events
> >      1.000103173                  0      msr/smi/
> >      2.000278816                  4      msr/smi/
> >      3.000472630                  4      msr/smi/
> >      4.000743916                  0      msr/smi/
> >      5.001369358                  4      msr/smi/
> >      6.001668033                  0      msr/smi/
> >      7.001852603                  4      msr/smi/
> >      8.002108269                 12      msr/smi/
> >      9.002367312                  0      msr/smi/
> > ^C     9.961897866                  0      msr/smi/
> >
> > [root@...et ~]#
> >
> > - Arnaldo
> >
> > > It's documented in PCH datasheet.
> > > https://www.intel.com/content/dam/www/public/us/en/
> > > documents/datasheets/9-series-chipset-pch-datasheet.pdf
> > >
> > > APM_CNT-Advanced Power Management Control Port Register I/O
> Address:
> > > B2h
> > > Attribute: R/W
> > > Default Value: 00h
> > > Size: 8 bits
> > > Lockable: No
> > > Usage: Legacy Only
> > > Power Well: Core
> > > Bit Description
> > > 7:0 Used to pass an APM command between the OS and the SMI handler.
> > > Writes to this port not only store data in the APMC register, but
> > > also generates an SMI# when the APMC_EN bit is set.
> > >
> > > You can write a byte to port 0xB2 to trigger an SMI#
> > >
> > > Thanks,
> > > Kan