linux-kernel - Re: [PATCH 2/2] tools/power/x86/intel-speed-select: Display core count for bucket

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Message-ID: <c6e4cedc4886fd689b3ff1df413ce62aa52cc544.camel@linux.intel.com>
Date:   Sun, 08 Sep 2019 07:43:14 -0700
From:   Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Andy Shevchenko <andriy.shevchenko@...el.com>,
        Prarit Bhargava <prarit@...hat.com>,
        David Arcari <darcari@...hat.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Platform Driver <platform-driver-x86@...r.kernel.org>
Subject: Re: [PATCH 2/2] tools/power/x86/intel-speed-select: Display core
 count for bucket

On Sat, 2019-09-07 at 21:18 +0300, Andy Shevchenko wrote:
> On Fri, Sep 6, 2019 at 10:47 PM Srinivas Pandruvada
> <srinivas.pandruvada@...ux.intel.com> wrote:
> > 
> > On Fri, 2019-09-06 at 07:50 -0700, Srinivas Pandruvada wrote:
> > > On Fri, 2019-09-06 at 16:46 +0300, Andy Shevchenko wrote:
> > > > On Fri, Sep 06, 2019 at 05:39:54AM -0400, Prarit Bhargava
> > > > wrote:
> > > > > On 9/5/19 7:37 PM, Srinivas Pandruvada wrote:
> > > > > > Read the bucket and core count relationship via MSR and
> > > > > > display
> > > > > > when displaying turbo ratio limits.
> > > > > > +       ret = isst_send_msr_command(cpu, 0x1ae, 0,
> > > > > > buckets_info);
> > > > > 
> > > > > ^^^ you can get rid of the magic number 0x1ae by doing (sorry
> > > > > for
> > > > > the cut-and-paste)
> > > > > 
> > > > > diff --git a/tools/power/x86/intel-speed-select/Makefile
> > > > > b/tools/power/x86/intel
> > > > > index 12c6939dca2a..087d802ad844 100644
> > > > > --- a/tools/power/x86/intel-speed-select/Makefile
> > > > > +++ b/tools/power/x86/intel-speed-select/Makefile
> > > > > @@ -15,6 +15,8 @@ endif
> > > > >  MAKEFLAGS += -r
> > > > > 
> > > > >  override CFLAGS += -O2 -Wall -g -D_GNU_SOURCE
> > > > > -I$(OUTPUT)include
> > > > > +override CFLAGS += -I../../../include
> > > > > +override CFLAGS +=
> > > > > -DMSRHEADER='"../../../../arch/x86/include/asm/msr-index.h"'
> > > 
> > > No, we can't use msr_index.
> > 
> > This comment was meant for use of /dev/cpu/X/msr not msr_index.
> > I didn't want to bring in dependency on msr-index.h for couple of 2
> > MSRs and the names in msr-index.h doesn't really reflect the actual
> > processing, they are doing. For example MSR_TURBO_RATIO_LIMIT1 for
> > 0x1ae. The definition of 0x1AE is different on cpu model 0x55 and
> > beyond.
> > 
> > > 
> 
> It seems not applicable on top of tools patch series I had applied
> before.
I have rebased on the top of your review branch and resent.

Thanks,
Srinivas

> 
> > > > 
> > > > I guess it can be done in more neat way.
> > > > 
> > > > > As I've been looking at this code I have been wondering why
> > > > > didn't
> > > > > you just use
> > > > > the standard /dev/cpu/X/msr interface that other x86 power
> > > > > utilities (turbostat,
> > > > > x86_energy_perf_policy) use?  Implementing msr_read() is
> > > > > trivial
> > > > > (warning
> > > > > untested and uncompiled code)
> > > 
> > > No. We can't. The MSR interface is disabled on several
> > > distribution
> > > and
> > > platforms with secured boot. So some special MSRs are only
> > > allowed
> > > via
> > > this IOCTL interface.
> > > 
> > > Thanks,
> > > Srinivas
> > > 
> > > 
> > > > 
> > > > Actually good point!
> > > > 
> 
>