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From: Peter Xu <peterx@redhat.com>
To: Nicolas Saenz Julienne <nsaenzju@redhat.com>
Cc: linux-rt-users@vger.kernel.org, williams@redhat.com, jkacur@redhat.com
Subject: Re: [PATCH 1/3] oslat: rename cpu_mhz/cpu_hz to timer_mhz/cpu_hz
Date: Wed, 8 Sep 2021 10:40:41 -0400	[thread overview]
Message-ID: <YTjLaZez4azBeYLI@t490s> (raw)
In-Reply-To: <20210908100209.118609-1-nsaenzju@redhat.com>

Hello, Nicolas,

On Wed, Sep 08, 2021 at 12:02:07PM +0200, Nicolas Saenz Julienne wrote:
> 'cpu_mhz' in oslat actually represents the frequency at which the high
> frequency timer we measure with ticks. There is no need for it to match
> the CPU frequency, nor will do on all supported architectures. So rename
> it to 'timer_mhz' in order to better match reality.

But right now "cpu_mhz" is indeed the cpu frequency per mhz, isn't it?  As I
believe that's how "time stamp counter" defined on x86. :)

I don't know what's the corresponding register for aarch64 to read the
processor clock cycles out, I did a quick google and it tells me PMCCNTR, but
I've no solid idea.  Or do you mean for some reason we can't read that info out
from aarch64?

Thanks,

-- 
Peter Xu


  parent reply	other threads:[~2021-09-08 14:40 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-08 10:02 [PATCH 1/3] oslat: rename cpu_mhz/cpu_hz to timer_mhz/cpu_hz Nicolas Saenz Julienne
2021-09-08 10:02 ` [PATCH 2/3] oslat: Add aarch64 support Nicolas Saenz Julienne
2021-09-08 18:09   ` Peter Xu
2021-09-09 10:10     ` nsaenzju
2021-09-09 18:03       ` Peter Xu
2021-09-10 12:19         ` nsaenzju
2021-09-10 13:33           ` Peter Xu
2021-09-10 14:27             ` nsaenzju
2021-09-10 17:00               ` Peter Xu
2021-09-08 10:02 ` [PATCH 3/3] oslat: Allow for arch specific timer frequency measurements Nicolas Saenz Julienne
2021-09-08 18:16   ` Peter Xu
2021-09-09 10:29     ` nsaenzju
2021-09-09 18:04       ` Peter Xu
2021-09-08 14:40 ` Peter Xu [this message]
2021-09-08 16:30   ` [PATCH 1/3] oslat: rename cpu_mhz/cpu_hz to timer_mhz/cpu_hz nsaenzju
2021-09-08 17:51     ` Peter Xu
2021-09-09  9:41       ` nsaenzju
2021-09-09 18:05         ` Peter Xu

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