5.4-prerelease - hanging under load

Nate Lawson nate at root.org
Sun Apr 3 21:44:03 PDT 2005

Greg 'groggy' Lehey wrote:
> On Sunday,  3 April 2005 at 14:45:40 -0700, Nate Lawson wrote:
>>Christian Brueffer wrote:
>>>On Sun, Apr 03, 2005 at 12:07:14PM -0400, Pierre-Luc Drouin wrote:
>>>>Christian Brueffer wrote:
>>>>>On Sat, Apr 02, 2005 at 09:16:48PM -0500, Pierre-Luc Drouin wrote:
>>>>>>Since I upgraded from 5.3-stable to 5.4-prerelease, I've noticed that
>>>>>>my computer is hanging badly under load. I've a P4 2.53 GHz without
>>>>>>hyperthreading (no SMP). I use the same kernel configurations than
>>>>>>before. Now when I compile a port for example, the mouse pointer hangs
>>>>>>in Fluxbox and Mozilla takes forever (meaning ~5 sec) to refresh the
>>>>>>screen. Even vi hangs. I do not see any warning/error message. Is it a
>>>>>>known problem with 5.4?
>>>>>I have experienced something similar, putting the following into rc.conf
>>>>>worked for me:
>>>>Yes, this seams to fix it. I didn't know that I had a laptop? :)
>>>Good to hear.
>>>Nate, this regression was introduced during the cpufreq and friends MFC.
>>>Is switching the performance_cpu_freq default to HIGH the way to go for
>>As you can see from etc/defaults/rc.conf on both -current and RELENG_5,
>>we don't currently change the frequency at all:
>>performance_cpu_freq="NONE"             # Online CPU frequency
>>economy_cpu_freq="NONE"                 # Offline CPU frequency
>>However, it sounds like his system's BIOS is booting up with a low
>>acpi_throttle setting (probably the lowest one, 12.5% on many systems)
>>and so he is seeing very slow performance.  (Only the acpi_throttle
>>cpufreq driver has been MFCd for the 5.4 release and the others will
>>follow the release.)  Initially, I thought it was safest not to even
>>touch the frequency but it looks like it is necessary for some systems
>>to always force it high by default.
> I'm experiencing similar issues.  How can I confirm that this is the
> case without rebooting the machine (which would be inconvenient)?  Is
> there some sysctl that tells me?  I've taken a look, but I don't see
> anything obvious.

sysctl dev.cpu and look at the current frequency setting.  If low, then 
your system is affected and will be fixed soon when I mfc.  If not, 
perhaps you have an interrupt storm (vmstat -i)


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