linux-kernel - Re: Commit fcb6a15c2e7e (intel_pstate: Take core C0 time into account for core busy calculation) sucks rocks

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Date:	Wed, 19 Feb 2014 16:35:37 -0800
From:	Greg KH <gregkh@...uxfoundation.org>
To:	Dirk Brandewie <dirk.brandewie@...il.com>
Cc:	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	cpufreq@...r.kernel.org, linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: Commit fcb6a15c2e7e (intel_pstate: Take core C0 time into
 account for core busy calculation) sucks rocks

On Wed, Feb 19, 2014 at 04:03:40PM -0800, Dirk Brandewie wrote:
> On 02/19/2014 02:47 PM, Greg KH wrote:
> >Hi Dirk,
> >
> >I've been having some huge slowdowns on my box building kernels, and I
> >took the time to bisect it down to commit
> >fcb6a15c2e7e76d493e6f91ea889ab40e1c643a4 (intel_pstate: Take core C0
> >time into account for core busy calculation).  With that patch reverted
> >on Linus's current tree, my build speeds are back up to the normal rate.
> >
> >The difference is huge, 2 minutes to do a kernel build with that patch
> >reverted, 8-10 minutes with it applied!  With all of the stable kernel
> >builds and other trees, this is a huge problem for my workload (all I do
> >is kernel builds it seems...)
> >
> >I see some patches you marked as "fixes" that you sent to Rafael, do you
> >want me to test any of those?  How am I the only one seeing this
> >problem, do you need my cpu information or anything else?
> 
> Can you give me a description of you build system?  CPU, number of sockets,

The last processor in /proc/cpuinfo:

processor       : 7
vendor_id       : GenuineIntel
cpu family      : 6
model           : 60
model name      : Intel(R) Core(TM) i7-4770K CPU @ 3.50GHz
stepping        : 3
microcode       : 0x9
cpu MHz         : 3556.464
cache size      : 8192 KB
physical id     : 0
siblings        : 8
core id         : 3
cpu cores       : 4
apicid          : 7
initial apicid  : 7
fpu             : yes
fpu_exception   : yes
cpuid level     : 13
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf eagerfpu pni pclmulqdq dtes64 monitor ds_cpl vmx est tm2 ssse3 fma cx16 xtpr pdcm pcid sse4_1 sse4_2 movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm ida arat epb xsaveopt pln pts dtherm tpr_shadow vnmi flexpriority ept vpid fsgsbase tsc_adjust bmi1 avx2 smep bmi2 erms invpcid
bogomips        : 7000.78
clflush size    : 64
cache_alignment : 64
address sizes   : 39 bits physical, 48 bits virtual

> building from/to local media.  Any special setup I should use here for my test?

I build on a SSD-like disk (flash media on PCI Express slot), so I
should have almost no i/o time.

I build with 'make -j16'

> If you have time having the output of turbostat for a build with and
> without would be very useful.

 $ ./turbostat
 turbostat: no /dev/cpu/0/msr
 Try "# modprobe msr": No such file or directory

Bah, I'll rebuild with msr and get you that info...

thanks,

greg k-h
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