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

From: Chuck Ebbert
Date: Sat Jul 01 2006 - 11:23:48 EST


In-Reply-To: <20060630204032.GB22835@xxxxxxxxxxxxxxxxx>

On Fri, 30 Jun 2006 13:40:32 -0700, Stephane Eranian wrote:

> As Andi is suggesting, I think this may depends on how the BIOS implements
> the low-power state. I have tried the same command on my dual Opteron 250
> 2.4GHz and I get:
> $ pfmon --us-c -ecpu_clk_unhalted,interrupts_masked_cycles -k --system-wide -t 10
> <session to end in 10 seconds>
> CPU0 9,520,303 CPU_CLK_UNHALTED
> CPU0 3,726,315 INTERRUPTS_MASKED_CYCLES
> CPU1 21,268,151 CPU_CLK_UNHALTED
> CPU1 14,515,389 INTERRUPTS_MASKED_CYCLES

That is similar to what I get with idle=halt. Are you not using ACPI
for idle?

Try this:

$ pfmon -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 95016828 CPU_CLK_UNHALTED
CPU0 36472783 INTERRUPTS_MASKED_CYCLES_WITH_INTERRUPT_PENDING
CPU0 67484408 INTERRUPTS_MASKED_CYCLES
CPU0 445326968 CYCLES_NO_FPU_OPS_RETIRED

That's what I get with idle=halt. Since the kernel doesn't do FP
the last line should equal clock cycles. If it were running at full
speed it would be 16 billion...

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