From: Thomas Gleixner <tglx@linutronix.de>
To: Adrian Hunter <adrian.hunter@intel.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
Andy Lutomirski <luto@amacapital.net>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andi Kleen <ak@linux.intel.com>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Len Brown <lenb@kernel.org>
Subject: Re: [PATCH RFC] x86, tsc: Allow for high latency in quick_pit_calibrate()
Date: Tue, 2 Jun 2015 21:33:25 +0200 (CEST) [thread overview]
Message-ID: <alpine.DEB.2.11.1506022130330.20347@nanos> (raw)
In-Reply-To: <1432194944-29087-1-git-send-email-adrian.hunter@intel.com>
On Thu, 21 May 2015, Adrian Hunter wrote:
> If it takes longer than 12us to read the PIT counter lsb/msb,
> then the error margin will never fall below 500ppm within 50ms,
> and Fast TSC calibration will always fail.
So finally the legacy PIT emulation takes longer than the 30 years old
hardware implementation. Progress!
> This patch detects when that will happen and switches to using
> a slightly different algorithm that takes advantage of the PIT's
> latch comand.
Is there really no smarter way to figure out the TSC frequency on
modern systems?
Thanks,
tglx
next prev parent reply other threads:[~2015-06-02 19:33 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-21 7:55 Adrian Hunter
2015-06-01 7:57 ` Adrian Hunter
2015-06-02 13:58 ` Thomas Gleixner
2015-06-02 19:33 ` Thomas Gleixner [this message]
2015-06-02 19:41 ` Andy Lutomirski
2015-06-02 19:43 ` Andi Kleen
2015-06-02 19:58 ` Thomas Gleixner
2015-06-02 20:03 ` Andy Lutomirski
2015-06-02 20:20 ` Andi Kleen
2015-06-02 21:03 ` Thomas Gleixner
2015-06-02 23:38 ` Andi Kleen
2015-06-03 0:21 ` Andy Lutomirski
2015-06-03 0:39 ` Andi Kleen
2015-06-03 0:58 ` Andy Lutomirski
2015-06-03 3:30 ` Andi Kleen
2015-06-03 8:13 ` Adrian Hunter
2015-06-03 13:45 ` Linus Torvalds
2015-06-04 11:28 ` Adrian Hunter
2015-06-03 16:23 ` Thomas Gleixner
2015-06-22 11:21 ` Adrian Hunter
2015-06-22 13:14 ` Thomas Gleixner
2015-07-06 6:48 ` Adrian Hunter
2015-07-06 7:42 ` Thomas Gleixner
2015-06-22 14:12 ` George Spelvin
2015-07-06 7:42 ` [tip:x86/urgent] x86/tsc: Let high latency PIT fail fast " tip-bot for Adrian Hunter
2015-06-03 4:20 ` [PATCH RFC] x86, tsc: Allow for high latency " Linus Torvalds
2015-06-03 6:20 ` Ingo Molnar
2015-06-03 13:43 ` Linus Torvalds
2015-06-03 16:47 ` Thomas Gleixner
2015-06-03 17:04 ` Linus Torvalds
2015-06-03 17:50 ` H. Peter Anvin
2015-06-04 12:32 ` Ingo Molnar
2015-06-03 17:06 ` Ingo Molnar
2015-06-03 6:27 George Spelvin
2015-06-03 18:29 ` George Spelvin
2015-06-03 18:48 ` H. Peter Anvin
2015-06-03 19:07 ` George Spelvin
2015-06-04 16:38 ` George Spelvin
2015-06-04 16:52 ` Linus Torvalds
2015-06-04 17:54 ` George Spelvin
2015-06-04 18:07 ` Linus Torvalds
2015-06-05 5:52 ` George Spelvin
2015-06-05 6:16 ` Ingo Molnar
2015-06-05 5:58 ` Ingo Molnar
2015-06-05 8:24 ` George Spelvin
2015-06-05 8:31 ` Ingo Molnar
2015-06-05 20:17 ` George Spelvin
2015-06-06 21:50 ` George Spelvin
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