Slow xterm response

Bill Moseley moseley at hank.org
Wed Dec 5 19:40:43 PST 2007


On Thu, Dec 06, 2007 at 02:26:47AM +0000, James Cloos wrote:

Ok, I don't think this is related to X, now.  Although X may provide a
solution.

I assumed it was X because it always happens when the screen blanks
either at the gdm login screen or when logged into my window manager.

But, I just did the obvious and removed gdm and rebooted.
I ssh'ed in and I *am* seeing the latency.  I don't see the latency
on the laptop (console).

So, now I'm really baffled.  Seems running X maybe *disables*
something that gets re-enabled when the screen is blanked???

Sure enough: if I "startx" the latency in the ssh terminal goes away.
Exiting X and it comes back.

I ran strace on both the bash and sshd processes on the laptop but
nothing interesting there.

I think I need a drink.




> What is under /sys/devices/system/cpu/?  There might be useful info
> there, too.

See below.


> Bill> Well, maybe a little.
> 
> That listing shows about an extra hundred or so INTs per second.
> 
> Periodic cat(1)s of /proc/interupts will show what is generating those
> extras.

I'm not seeing anything very significant.  Odd that all the interrupts
are on CPU0.  I've been running this over and over and nothing jumps
out when the latency starts.

moseley at tiger:~$ cat /proc/interrupts 
           CPU0       CPU1       
  0:     248647          1   IO-APIC-edge      timer
  1:         10          0   IO-APIC-edge      i8042
  8:          7          0   IO-APIC-edge      rtc
  9:       6655          0   IO-APIC-fasteoi   acpi
 12:       7492          0   IO-APIC-edge      i8042
 14:     103254          0   IO-APIC-edge      libata
 15:          0          0   IO-APIC-edge      libata
 16:     490320          0   IO-APIC-fasteoi   uhci_hcd:usb1, ahci, yenta, eth0, fglrx
 21:     101767          0   IO-APIC-fasteoi   uhci_hcd:usb2, wifi0, HDA Intel
 22:          0          0   IO-APIC-fasteoi   uhci_hcd:usb3
 23:         56          0   IO-APIC-fasteoi   uhci_hcd:usb4, ehci_hcd:usb5
NMI:          0          0 
LOC:       6174      72575 
ERR:          0
MIS:          0

With latency:

moseley at tiger:~$ cat /proc/interrupts 
           CPU0       CPU1       
  0:     249063          1   IO-APIC-edge      timer
  1:         10          0   IO-APIC-edge      i8042
  8:          7          0   IO-APIC-edge      rtc
  9:       6655          0   IO-APIC-fasteoi   acpi
 12:       7492          0   IO-APIC-edge      i8042
 14:     103342          0   IO-APIC-edge      libata
 15:          0          0   IO-APIC-edge      libata
 16:     490872          0   IO-APIC-fasteoi   uhci_hcd:usb1, ahci, yenta, eth0, fglrx
 21:     101898          0   IO-APIC-fasteoi   uhci_hcd:usb2, wifi0, HDA Intel
 22:          0          0   IO-APIC-fasteoi   uhci_hcd:usb3
 23:         56          0   IO-APIC-fasteoi   uhci_hcd:usb4, ehci_hcd:usb5
NMI:          0          0 
LOC:       6264      72746 
ERR:          0
MIS:          0

moseley at tiger:~$ find /sys/devices/system/cpu/
/sys/devices/system/cpu/
/sys/devices/system/cpu/cpu1
/sys/devices/system/cpu/cpu1/cpufreq
/sys/devices/system/cpu/cpu1/topology
/sys/devices/system/cpu/cpu1/topology/core_siblings
/sys/devices/system/cpu/cpu1/topology/thread_siblings
/sys/devices/system/cpu/cpu1/topology/core_id
/sys/devices/system/cpu/cpu1/topology/physical_package_id
/sys/devices/system/cpu/cpu1/cache
/sys/devices/system/cpu/cpu1/cache/index2
/sys/devices/system/cpu/cpu1/cache/index2/shared_cpu_map
/sys/devices/system/cpu/cpu1/cache/index2/size
/sys/devices/system/cpu/cpu1/cache/index2/number_of_sets
/sys/devices/system/cpu/cpu1/cache/index2/ways_of_associativity
/sys/devices/system/cpu/cpu1/cache/index2/physical_line_partition
/sys/devices/system/cpu/cpu1/cache/index2/coherency_line_size
/sys/devices/system/cpu/cpu1/cache/index2/level
/sys/devices/system/cpu/cpu1/cache/index2/type
/sys/devices/system/cpu/cpu1/cache/index1
/sys/devices/system/cpu/cpu1/cache/index1/shared_cpu_map
/sys/devices/system/cpu/cpu1/cache/index1/size
/sys/devices/system/cpu/cpu1/cache/index1/number_of_sets
/sys/devices/system/cpu/cpu1/cache/index1/ways_of_associativity
/sys/devices/system/cpu/cpu1/cache/index1/physical_line_partition
/sys/devices/system/cpu/cpu1/cache/index1/coherency_line_size
/sys/devices/system/cpu/cpu1/cache/index1/level
/sys/devices/system/cpu/cpu1/cache/index1/type
/sys/devices/system/cpu/cpu1/cache/index0
/sys/devices/system/cpu/cpu1/cache/index0/shared_cpu_map
/sys/devices/system/cpu/cpu1/cache/index0/size
/sys/devices/system/cpu/cpu1/cache/index0/number_of_sets
/sys/devices/system/cpu/cpu1/cache/index0/ways_of_associativity
/sys/devices/system/cpu/cpu1/cache/index0/physical_line_partition
/sys/devices/system/cpu/cpu1/cache/index0/coherency_line_size
/sys/devices/system/cpu/cpu1/cache/index0/level
/sys/devices/system/cpu/cpu1/cache/index0/type
/sys/devices/system/cpu/cpu1/crash_notes
/sys/devices/system/cpu/cpu1/online
/sys/devices/system/cpu/cpu0
/sys/devices/system/cpu/cpu0/cpufreq
/sys/devices/system/cpu/cpu0/cpufreq/ondemand
/sys/devices/system/cpu/cpu0/cpufreq/ondemand/powersave_bias
/sys/devices/system/cpu/cpu0/cpufreq/ondemand/ignore_nice_load
/sys/devices/system/cpu/cpu0/cpufreq/ondemand/up_threshold
/sys/devices/system/cpu/cpu0/cpufreq/ondemand/sampling_rate
/sys/devices/system/cpu/cpu0/cpufreq/ondemand/sampling_rate_min
/sys/devices/system/cpu/cpu0/cpufreq/ondemand/sampling_rate_max
/sys/devices/system/cpu/cpu0/cpufreq/stats
/sys/devices/system/cpu/cpu0/cpufreq/stats/trans_table
/sys/devices/system/cpu/cpu0/cpufreq/stats/time_in_state
/sys/devices/system/cpu/cpu0/cpufreq/stats/total_trans
/sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq
/sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_cur_freq
/sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies
/sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors
/sys/devices/system/cpu/cpu0/cpufreq/scaling_driver
/sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
/sys/devices/system/cpu/cpu0/cpufreq/affected_cpus
/sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq
/sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq
/sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq
/sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_min_freq
/sys/devices/system/cpu/cpu0/topology
/sys/devices/system/cpu/cpu0/topology/core_siblings
/sys/devices/system/cpu/cpu0/topology/thread_siblings
/sys/devices/system/cpu/cpu0/topology/core_id
/sys/devices/system/cpu/cpu0/topology/physical_package_id
/sys/devices/system/cpu/cpu0/cache
/sys/devices/system/cpu/cpu0/cache/index2
/sys/devices/system/cpu/cpu0/cache/index2/shared_cpu_map
/sys/devices/system/cpu/cpu0/cache/index2/size
/sys/devices/system/cpu/cpu0/cache/index2/number_of_sets
/sys/devices/system/cpu/cpu0/cache/index2/ways_of_associativity
/sys/devices/system/cpu/cpu0/cache/index2/physical_line_partition
/sys/devices/system/cpu/cpu0/cache/index2/coherency_line_size
/sys/devices/system/cpu/cpu0/cache/index2/level
/sys/devices/system/cpu/cpu0/cache/index2/type
/sys/devices/system/cpu/cpu0/cache/index1
/sys/devices/system/cpu/cpu0/cache/index1/shared_cpu_map
/sys/devices/system/cpu/cpu0/cache/index1/size
/sys/devices/system/cpu/cpu0/cache/index1/number_of_sets
/sys/devices/system/cpu/cpu0/cache/index1/ways_of_associativity
/sys/devices/system/cpu/cpu0/cache/index1/physical_line_partition
/sys/devices/system/cpu/cpu0/cache/index1/coherency_line_size
/sys/devices/system/cpu/cpu0/cache/index1/level
/sys/devices/system/cpu/cpu0/cache/index1/type
/sys/devices/system/cpu/cpu0/cache/index0
/sys/devices/system/cpu/cpu0/cache/index0/shared_cpu_map
/sys/devices/system/cpu/cpu0/cache/index0/size
/sys/devices/system/cpu/cpu0/cache/index0/number_of_sets
/sys/devices/system/cpu/cpu0/cache/index0/ways_of_associativity
/sys/devices/system/cpu/cpu0/cache/index0/physical_line_partition
/sys/devices/system/cpu/cpu0/cache/index0/coherency_line_size
/sys/devices/system/cpu/cpu0/cache/index0/level
/sys/devices/system/cpu/cpu0/cache/index0/type
/sys/devices/system/cpu/cpu0/crash_notes
/sys/devices/system/cpu/sched_mc_power_savings



-- 
Bill Moseley
moseley at hank.org




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