From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: John Stultz <john.stultz@linaro.org>
Cc: Matt Sealey <matt@genesi-usa.com>, Arnd Bergmann <arnd@arndb.de>,
Linux ARM Kernel ML <linux-arm-kernel@lists.infradead.org>,
LKML <linux-kernel@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>
Subject: Re: One of these things (CONFIG_HZ) is not like the others..
Date: Mon, 21 Jan 2013 22:49:00 +0000 [thread overview]
Message-ID: <20130121224900.GB23505@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <50FDC2DD.7090406@linaro.org>
On Mon, Jan 21, 2013 at 02:36:13PM -0800, John Stultz wrote:
> Well, Russell brought up a case that doesn't handle this. If a system
> *can't* do HZ=100, but can do HZ=200.
>
> Though there are hacks, of course, that might get around this (skip
> every other interrupt at 200HZ).
Note: in the early days of EBSA110 support, yes, we did that, so that
we could have HZ=100 everywhere. _However_ it sufficiently peturbed
NTP that it basically was unable to slew the clock in any sane manner.
I never got to the bottom of why that was, and when USER_HZ was
decoupled from the kernel HZ, it allowed the problem to be fixed, and
the kernel code to become a _lot_ cleaner.
next prev parent reply other threads:[~2013-01-21 22:49 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-21 20:01 One of these things (CONFIG_HZ) is not like the others Matt Sealey
2013-01-21 20:41 ` Arnd Bergmann
2013-01-21 21:00 ` John Stultz
2013-01-21 21:12 ` Russell King - ARM Linux
2013-01-21 22:18 ` John Stultz
2013-01-21 22:44 ` Russell King - ARM Linux
2013-01-22 8:27 ` Arnd Bergmann
2013-01-21 22:20 ` Matt Sealey
2013-01-21 22:42 ` Russell King - ARM Linux
2013-01-21 23:23 ` Matt Sealey
2013-01-21 23:49 ` Russell King - ARM Linux
2013-01-22 0:09 ` Matt Sealey
2013-01-22 0:26 ` Matt Sealey
2013-01-21 21:14 ` Matt Sealey
2013-01-21 22:36 ` John Stultz
2013-01-21 22:49 ` Russell King - ARM Linux [this message]
2013-01-21 22:54 ` Matt Sealey
2013-01-21 23:13 ` Russell King - ARM Linux
2013-01-21 23:30 ` Matt Sealey
2013-01-22 0:02 ` Russell King - ARM Linux
2013-01-22 0:38 ` John Stultz
2013-01-22 0:51 ` John Stultz
2013-01-22 1:06 ` Matt Sealey
2013-01-22 1:18 ` Russell King - ARM Linux
2013-01-22 1:56 ` Matt Sealey
2013-01-22 1:31 ` John Stultz
2013-01-22 2:10 ` Matt Sealey
2013-01-31 21:31 ` Thomas Gleixner
2013-01-21 21:02 ` Matt Sealey
2013-01-21 22:30 ` Arnd Bergmann
2013-01-21 22:45 ` Russell King - ARM Linux
2013-01-21 23:01 ` Matt Sealey
2013-01-21 21:03 ` Russell King - ARM Linux
2013-01-21 23:23 ` Tony Lindgren
2013-01-22 6:23 ` Santosh Shilimkar
2013-01-22 9:31 ` Arnd Bergmann
2013-01-22 10:14 ` Santosh Shilimkar
2013-01-22 14:51 ` Russell King - ARM Linux
2013-01-22 15:05 ` Santosh Shilimkar
2013-01-28 6:08 ` Santosh Shilimkar
2013-01-29 0:01 ` John Stultz
2013-01-29 6:43 ` Santosh Shilimkar
2013-01-29 10:06 ` Russell King - ARM Linux
2013-01-29 18:43 ` John Stultz
2013-01-22 17:31 ` Arnd Bergmann
2013-01-22 18:59 ` John Stultz
2013-01-22 21:52 ` Tony Lindgren
2013-01-23 5:18 ` Santosh Shilimkar
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