From: Peter Zijlstra <peterz@infradead.org>
To: Jason Vas Dias <jason.vas.dias@gmail.com>
Cc: x86@kernel.org, LKML <linux-kernel@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>, andi <andi@firstfloor.org>
Subject: Re: [PATCH v4.16-rc4 2/2] x86/vdso: on Intel, VDSO should handle CLOCK_MONOTONIC_RAW
Date: Wed, 14 Mar 2018 14:12:37 +0100 [thread overview]
Message-ID: <20180314131237.GL4064@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <CALyZvKzbLi6K9DFwOXu7h--MdxWFv9A3==0xORuQ=KwtJx3ZrQ@mail.gmail.com>
On Wed, Mar 14, 2018 at 12:55:20PM +0000, Jason Vas Dias wrote:
> > While CPU_CLOCK is TSC based, there is no guarantee it has any
> > correlation to CLOCK_MONOTONIC_RAW (even if that is also TSC based).
> >
> > (although, I think I might have fixed that recently and it might just
> > work, but it's very much not guaranteed).
>
> Yes, I believe the CPU_CLOCK is effectively the converted TSC -
> it does appear to correlate well with the new CLOCK_MONOTONIC_RAW
> values from the patched VDSO.
It (now) runs at the same rate, but there is no guarantee for this, in
fact it didn't for a very long time.
Relying on this is broken.
next prev parent reply other threads:[~2018-03-14 13:12 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-12 7:01 [PATCH v4.16-rc4 2/2] x86/vdso: on Intel, VDSO should handle CLOCK_MONOTONIC_RAW Jason Vas Dias
2018-03-12 8:27 ` Peter Zijlstra
2018-03-13 23:45 ` Jason Vas Dias
2018-03-14 9:45 ` Peter Zijlstra
2018-03-14 12:55 ` Jason Vas Dias
2018-03-14 13:11 ` Peter Zijlstra
2018-03-14 13:12 ` Peter Zijlstra [this message]
2018-03-14 13:16 ` Peter Zijlstra
2018-03-14 13:29 ` Peter Zijlstra
-- strict thread matches above, loose matches on Subject: below --
2018-03-12 9:14 Jason Vas Dias
2018-03-12 17:41 ` kbuild test robot
2018-03-12 5:44 Jason Vas Dias
2018-03-12 5:33 Jason Vas Dias
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=20180314131237.GL4064@hirez.programming.kicks-ass.net \
--to=peterz@infradead.org \
--cc=andi@firstfloor.org \
--cc=jason.vas.dias@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.