On 30 Sep, Andriy Gapon wrote:
> on 30/09/2010 02:27 Don Lewis said the following:

>> I tried enabling apic and got worse results.  I saw ping RTTs as high as
>> 67 seconds.  Here's the timer info with apic enabled:
[snip]
>> Here's the verbose boot info with apic:
>> <http://people.freebsd.org/~truckman/AN-M2_HD-8.1-STABLE-apic-verbose.txt>
> 
> vmstat -i ?

Here's the vmstat -i output at the time the machine starts experiencing
freezes and ntp goes insane:

Thu Sep 30 11:38:57 PDT 2010
interrupt                          total       rate
irq1: atkbd0                           6          0
irq9: acpi0                           10          0
irq12: psm0                           18          0
irq14: ata0                         2845          1
irq17: ahc0                          310          0
irq19: fwohci0                         1          0
irq22: ehci0+                      74628         40
cpu0: timer                      3676399       1999
irq256: nfe0                        3915          2
Total                            3758132       2043
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
*gw.catspoiler.o .GPS.            1 u  129  128  377    0.185   -0.307   0.020

Thu Sep 30 11:39:59 PDT 2010
interrupt                          total       rate
irq1: atkbd0                           6          0
irq9: acpi0                           10          0
irq12: psm0                           18          0
irq14: ata0                         2935          1
irq17: ahc0                          310          0
irq19: fwohci0                         1          0
irq22: ehci0+                      78954         41
cpu0: timer                      3796447       1998
irq256: nfe0                        4090          2
Total                            3882771       2043
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
*gw.catspoiler.o .GPS.            1 u   61  128  377    0.185   -0.307   0.023

Thu Sep 30 11:40:59 PDT 2010
interrupt                          total       rate
irq1: atkbd0                           6          0
irq9: acpi0                           10          0
irq12: psm0                           18          0
irq14: ata0                         3025          1
irq17: ahc0                          310          0
irq19: fwohci0                         1          0
irq22: ehci0+                      85038         43
cpu0: timer                      3916483       1998
irq256: nfe0                        4247          2
Total                            4009138       2045
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
*gw.catspoiler.o .GPS.            1 u  121  128  377    0.185   -0.307   0.023

Thu Sep 30 11:41:59 PDT 2010
interrupt                          total       rate
irq1: atkbd0                           6          0
irq9: acpi0                           10          0
irq12: psm0                           18          0
irq14: ata0                         3115          1
irq17: ahc0                          310          0
irq19: fwohci0                         1          0
irq22: ehci0+                      89099         44
cpu0: timer                      4036529       1998
irq256: nfe0                        4384          2
Total                            4133472       2046
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
*gw.catspoiler.o .GPS.            1 u   54  128  377    0.185   -0.307 43008.9

Thu Sep 30 11:42:59 PDT 2010
interrupt                          total       rate
irq1: atkbd0                           6          0
irq9: acpi0                           11          0
irq12: psm0                           18          0
irq14: ata0                         3205          1
irq17: ahc0                          310          0
irq19: fwohci0                         1          0
irq22: ehci0+                      92111         44
cpu0: timer                      4156575       1998
irq256: nfe0                        4421          2
Total                            4256658       2046
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
*gw.catspoiler.o .GPS.            1 u  114  128  377    0.185   -0.307 43008.9

Thu Sep 30 11:43:59 PDT 2010
interrupt                          total       rate
irq1: atkbd0                           6          0
irq9: acpi0                           12          0
irq12: psm0                           18          0
irq14: ata0                         3295          1
irq17: ahc0                          310          0
irq19: fwohci0                         1          0
irq22: ehci0+                      92132         43
cpu0: timer                      4276621       1998
irq256: nfe0                        4444          2
Total                            4376839       2045
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
 gw.catspoiler.o .GPS.            1 u   44  128  377    0.177  113790. 105350.



I also hacked a kernel compiled with SMP so that it only finds one CPU
core.  The machine still freezes and causes long ping RTTs and ntp
insanity.

BTW, I first tried the above test by disabling the second core using the
machdep.hlt_cpus sysctl knob.  The results were most entertaining.  When
I tried to run "make index", it would hang early on.  It looked like
SCHED_ULE was trying to schedule the processes at both ends of a pipe on
both CPU cores even though it should have only been trying to use one
core.  The downstream process would then wait forever in piperd.

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