From: David Laight <David.Laight@ACULAB.COM>
To: "x86@kernel.org" <x86@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Running an Ivy Bridge cpu at fixed frequency
Date: Wed, 4 Dec 2019 17:01:32 +0000 [thread overview]
Message-ID: <8eeee0695c664305ba6a56bce42a995f@AcuMS.aculab.com> (raw)
Is there any way to persuade the intel_pstate driver to make an Ivy bridge (i7-3770)
cpu run at a fixed frequency?
It is really difficult to compare code execution times when the cpu clock speed
keeps changing.
I thought I'd managed by setting the 'scaling_max_freq' to 1.7GHz, but even that
doesn't seem to be working now.
It would also be nice to run a little faster than that - but without it 'randomly'
going to 'turbo' frequencies (which it is doing even after I've set no_turbo to 1).
An alternative would be a variable frequency TSC - might give more consistent values.
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next reply other threads:[~2019-12-04 17:01 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-04 17:01 David Laight [this message]
2019-12-04 17:57 ` Andy Lutomirski
2019-12-05 9:45 ` Peter Zijlstra
2019-12-05 15:53 ` David Laight
2019-12-05 17:51 ` Andy Lutomirski
2019-12-06 10:15 ` Peter Zijlstra
2019-12-06 13:06 ` David Laight
2019-12-06 14:47 ` Alexey Klimov
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