Re: [PATCH 10/17] 2.6.17.1 perfmon2 patch for review: PMU context switch

[Chuck Ebbert]

In-Reply-To: <20060704152857.GA6999@xxxxxxxxxxxxxxxxx>

On Tue, 4 Jul 2006 08:28:57 -0700, Stephan Eranian wrote:

> Here is what I get on my dual 2.4GHz Opteron 250:
> 
> booted with idle=halt
> $ pfmon --us-c -ecpu_clk_unhalted,interrupts_masked_cycles_with_interrupt_pending,interrupts_masked_cycles,cycles_no_fpu_ops_retired -k --system-wide -t 10
> <session to end in 10 seconds>
> CPU0                    11,356,210 CPU_CLK_UNHALTED                               
> CPU0                             0 INTERRUPTS_MASKED_CYCLES_WITH_INTERRUPT_PENDING
> CPU0                     3,836,107 INTERRUPTS_MASKED_CYCLES                       
> CPU0                23,910,784,532 CYCLES_NO_FPU_OPS_RETIRED                      
> CPU1                    19,303,632 CPU_CLK_UNHALTED                               
> CPU1                             0 INTERRUPTS_MASKED_CYCLES_WITH_INTERRUPT_PENDING
> CPU1                    13,942,265 INTERRUPTS_MASKED_CYCLES                       
> CPU1                23,911,872,654 CYCLES_NO_FPU_OPS_RETIRED                      

So it looks like your Opteron continues to count CYCLES_NO_FPU_OPS_RETIRED
at full clock speed even when halted.

My Turion appears to slow down to ~40 MHz when halted and counts those
events at that speed.  Using idle=poll shows no slowdown, as expected,
and unhalted clocks equals cycles_no_fpu_ops_retired.

-- 
Chuck
 "You can't read a newspaper if you can't read."  --George W. Bush
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