Slow xterm response

[Bill Moseley]

On Wed, Dec 05, 2007 at 08:43:13PM +0000, James Cloos wrote:
> >>>>> "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.

Well, I'm not so sure.  There's dpms which disables the display but
there's also the standard screen blanking that happens at 10 minutes.
I just assumed that was X clearing the screen (the LCD backlight is
still on).

That's when the latency starts.  Then if I force the display off after
the screen is blanked  the latency goes away.

If I change the timeout to 5 minutes then the latency starts at 5
minutes.  So, it seems to be triggered by blanking.

What I find odd is if the screen is *not* blanked then I have to run
"dpms force off" twice.  The first time *start* the latency.

Odd.

BTW -- yes the laptop is plugged in.


> 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.

/proc/acpi/processor/CPU0/performance: No such file or directory


> Is there any change in the rate of interupts when the latency occurs?
> Try triggering the latency while running vmstat(1) on the laptop.

I see no change in vmstat when the latency starts.

Well, maybe a little.  This starts off with latency showing and then I
ran xset dpms force off about where I added the line break.  Dose not
seem significant.


moseley at tiger:~$ vmstat 1
procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu----
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa
 0  0      0 1749552  14044 176404    0    0    23     8   69   49  0  0 99  1
 0  0      0 1749536  14044 176404    0    0     0     0   38   38  0  0 100  0
 0  0      0 1749544  14060 176400    0    0     0   260   61  110  0  0 100  0
 0  0      0 1749544  14060 176404    0    0     0     0   35   38  0  0 100  0
 0  0      0 1749544  14060 176404    0    0     0     0   78  126  0  0 100  0
 0  0      0 1749536  14060 176404    0    0     0     0   46   62  0  0 100  0
 0  0      0 1749544  14060 176404    0    0     0     0   58  101  0  0 100  0
 1  0      0 1749544  14060 176404    0    0     0     0   30   31  0  0 100  0
 0  0      0 1749544  14060 176404    0    0     0     0   61  102  0  0 100  0
 2  0      0 1749544  14060 176404    0    0     0     0   35   37  0  0 100  0

 0  0      0 1749620  14068 176396    0    0     0    16  151  369  1  0 99  0
 0  0      0 1749660  14068 176404    0    0     0     0  125   35  0  0 100  0
 0  0      0 1749660  14068 176404    0    0     0     0  157  103  0  0 100  0
 0  0      0 1749668  14068 176404    0    0     0     0  128   41  0  0 100  0
 0  0      0 1749668  14068 176404    0    0     0     0  156   97  0  0 100  0
 0  0      0 1749668  14068 176404    0    0     0     0  131   38  0  0 100  0
 0  0      0 1749668  14084 176404    0    0     0   196  158  114  0  0 100  0
 0  0      0 1749668  14084 176404    0    0     0     0  132   39  0  0 100  0
 0  0      0 1749668  14084 176404    0    0     0     0  157  107  0  0 100  0
 0  0      0 1749668  14084 176404    0    0     0     0  138   39  0  0 100  0
 0  0      0 1749668  14084 176404    0    0     0     0  159   99  0  0 100  0
 0  0      0 1749668  14084 176404    0    0     0     0  130   38  0  0 100  0
 1  0      0 1749668  14084 176404    0    0     0     0  158   99  0  0 100  0
 0  0      0 1749668  14084 176404    0    0     0     0  130   42  0  0 100  0
 0  0      0 1749668  14084 176404    0    0     0     0  165  111  0  0 100  0
 0  0      0 1749660  14084 176404    0    0     0     0  135   37  0  0 100  0





-- 
Bill Moseley
moseley at hank.org