Slow xterm response
cloos+pdx-xorg at jhcloos.com
Wed Dec 5 12:43:13 PST 2007
>>>>> "Bill" == Bill Moseley <moseley at hank.org> writes:
Bill> ... on my desktop I ssh into the laptop and start up a development
Bill> web application.
Bill> As soon as the laptop's screen goes blank my xterm sessions show
Bill> latency. If I hold down a key and repeat a letter it goes along in
Bill> fits and starts.
You wrote elsewhere in the thread that the blanking isn't caused by X
dpms but [I presume] by the laptop's firmware and/or kernel.
You also wrote that the MHz rating as exported in /proc/cpuinfo remains
constant, so the CPU's P state isn't changing. You may be, however,
seeing a problem with C states. If you're kernel is so configured,
/proc/acpi/processor/CPU0/performance will show the P states and
/proc/acpi/processor/CPU0/power the C states. Check whether those
change when the screen blanks.
Is there any change in the rate of interupts when the latency occurs?
Try triggering the latency while running vmstat(1) on the laptop.
There was a post in the last few days on linux-kernel showing a bug in
C state handling, where the poster's laptop would fall into a cycle of
continuously trying to switch to a lower-wattage C state just to be
immediately woken back up. You may be seeing something like that.
James Cloos <cloos at jhcloos.com> OpenPGP: 1024D/ED7DAEA6
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