From: Dave Jones <davej@redhat.com>
To: Tim Chen <tim.c.chen@linux.intel.com>
Cc: George Spelvin <linux@horizon.com>,
herbert@gondor.apana.org.au, james.guilford@intel.com,
JBeulich@suse.com, linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH] crypto: crc32c-pclmul - Use pmovzxdq to shrink K_table
Date: Thu, 29 May 2014 21:16:36 -0400 [thread overview]
Message-ID: <20140530011636.GA31694@redhat.com> (raw)
In-Reply-To: <1401412036.2970.459.camel@schen9-DESK>
On Thu, May 29, 2014 at 06:07:16PM -0700, Tim Chen wrote:
> On Thu, 2014-05-29 at 19:54 -0400, George Spelvin wrote:
> > Sorry for the delay; my Ivy Bridge test machine isn't in my
> > office and getting to the console to tweak the BIOS is a
> > bit of a bother.
> >
> > Anyway, i7-4930K, turbo boost & hyperthreading disabled,
> > $ cat /sys/devices/system/cpu/cpu?/cpufreq/scaling_governor
> > performance
> > performance
> > performance
> > performance
> > performance
> > performance
> >
> > Oddly, though, CPU speed still seems to be fluctuating:
> > $ grep MHz /proc/cpuinfo
> > cpu MHz : 1255.875
> > cpu MHz : 3168.375
> > cpu MHz : 3062.125
> > cpu MHz : 1468.375
> > cpu MHz : 1309.000
> > cpu MHz : 2212.125
> > $ grep MHz /proc/cpuinfo
> > cpu MHz : 1255.875
> > cpu MHz : 2690.250
> > cpu MHz : 1255.875
> > cpu MHz : 2530.875
> > cpu MHz : 2212.125
> > cpu MHz : 1521.500
>
> This is odd. On my Ivy Bridge system the CPU speed from /proc/cpuinfo
> is at max freq once I set the performance governor.
> The numbers above almost look like
> the cpu frequency is fluctuating and an average is taken.
> What version of the kernel are you running? Is
> CONFIG_CPU_FREQ_GOV_PERFORMANCE compiled in?
>
> Does /sys/devices/system/cpu/cpu?/cpufreq/scaling_cur_freq
> also changes?
>
> Can you check what are the available governors in your system
> and available frequencies?
>
> cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors
> cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies
>
> If userspace governor is available, you can try set the governor
> to userspace, then pin frequency to 3400 MHz (assuming that's your
> max) with command like:
intel_pstate overrides any governor choice you make through sysfs.
Dave
next prev parent reply other threads:[~2014-05-30 1:17 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-28 14:40 [RFC PATCH] crypto: crc32c-pclmul - Use pmovzxdq to shrink K_table George Spelvin
2014-05-28 15:32 ` George Spelvin
2014-05-28 22:15 ` [PATCH v2] crypto: crc32c-pclmul - Shrink K_table to 32-bit words George Spelvin
2014-05-28 23:02 ` Tim Chen
2014-05-28 23:55 ` George Spelvin
2014-05-29 3:26 ` George Spelvin
2014-05-29 16:33 ` Tim Chen
2014-05-28 20:47 ` [RFC PATCH] crypto: crc32c-pclmul - Use pmovzxdq to shrink K_table Jan Beulich
2014-05-28 21:47 ` George Spelvin
2014-05-29 6:44 ` Jan Beulich
2014-05-28 22:32 ` Tim Chen
2014-05-28 23:01 ` George Spelvin
2014-05-28 23:28 ` Tim Chen
2014-05-29 23:54 ` George Spelvin
2014-05-30 1:07 ` Tim Chen
2014-05-30 1:16 ` Dave Jones [this message]
2014-05-30 17:56 ` Tim Chen
2014-05-30 18:45 ` Dirk Brandewie
2014-05-30 19:32 ` Tim Chen
2014-05-30 19:38 ` Dirk Brandewie
2014-05-30 20:07 ` Tim Chen
2014-05-30 20:15 ` Dirk Brandewie
2014-05-30 1:37 ` George Spelvin
2014-05-30 5:25 ` George Spelvin
2014-05-30 16:10 ` Tim Chen
2014-05-30 16:52 ` George Spelvin
2014-05-30 17:01 ` Tim Chen
2014-06-07 3:08 ` [PATCH v3] crypto: crc32c-pclmul - Shrink K_table to 32-bit words George Spelvin
2014-06-20 18:42 ` Herbert Xu
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