Chuck,
On Tue, Jun 27, 2006 at 01:57:39AM -0400, Chuck Ebbert wrote:
> It works:
>
> $ pfmon --system-wide -0 -e interrupts_masked_cycles,interrupts_taken --edge-mask 0,1 -t 10
> <session to end in 10 seconds>
> CPU0 16359 INTERRUPTS_MASKED_CYCLES
> CPU0 5006 INTERRUPTS_TAKEN
>
> 5006 hardware interrupts in 10 seconds, 16359 interrupt-disable events ==>
> the kernel disabled interrupts 11353 times for critical sections. To get
> useful results it looks like booting with idle=poll and disabling cpufreq
> is needed, though, since interrupts_masked_cycles (non-edge mode) counts
> even when the CPU is halted:
Yes, I think you need to be careful with the idle thread, some events may or
may not count when going low-power. I think it is best to avoid going
low-power for measurements. It is also useful for some measurements to
exclude the idle task, i.e., to get useful kernel execution. For that
you can use the --excl-idle option of pfmon.
>
> $ pfmon --system-wide -0 -e interrupts_masked_cycles,cpu_clk_unhalted -t 10
> <session to end in 10 seconds>
> CPU0 352020255 INTERRUPTS_MASKED_CYCLES
> CPU0 65351172 CPU_CLK_UNHALTED
>
> > > And is someone working on kernel profiling tools that use the perfmon2
> > > infrastructure on i386? I'd like to see kernel-based profiling that lets
> > > you use something like the existing 'readprofile' to retrieve results. This
> > > would be a lot better than the current timer-based profiling.
> > >
> > You can do this on your athlon using pfmon already, you need to enable a
> > different sampling module. Here is an example:
> >
> > $ pfmon --smpl-module=inst-hist -ecpu_clk_unhalted -k --long-smpl-period=100000 \
> > --resolve-addr --system-wide --session-timeout=10
>
> That produces no output except for column headings. Thinking it was a problem with
> x86_64 32-bit support, I built a p6 version. I tried both short and long
> periods on both systems with the same result:
I think this is an issue with the NMI setup. I have looked at the code and found
some problems. They wil be fixed in the next patch. I suspect that if you say nmi_watchdog=2
on the kernel cmdline, it will work.
I have added the following 3 patches.
Thanks.
>
> perfmon: add Pentium II support (family 6 model 3 only.)
>
> --- 2.6.17.1-d4-pfmon.orig/arch/i386/perfmon/perfmon_p6.c
> +++ 2.6.17.1-d4-pfmon/arch/i386/perfmon/perfmon_p6.c
> @@ -76,6 +76,9 @@ static int pfm_p6_probe_pmu(void)
> }
>
> switch(cpu_data->x86_model) {
> + case 3:
> + PFM_INFO("Pentium II PMU detected");
> + break;
> case 7 ... 11:
> PFM_INFO("P6 core PMU detected");
> break;
> _
>
> libpfm: Add Pentium II support (family 6 model 3 only.)
>
> --- libpfm-3.2-060621.orig/lib/pfmlib_i386_p6.c
> +++ libpfm-3.2-060621/lib/pfmlib_i386_p6.c
> @@ -136,6 +136,7 @@ pfm_i386_p6_detect(void)
> return PFMLIB_ERR_NOTSUPP;
>
> switch(model) {
> + case 3: /* Pentium II */
> case 7: /* Pentium III Katmai */
> case 8: /* Pentium III Coppermine */
> case 9: /* Mobile Pentium III */
> _
>
> pfmon: don't build gen_ia32 sample module if not configured.
>
> --- pfmon-3.2-060621.orig/pfmon/pfmon_smpl.c
> +++ pfmon-3.2-060621/pfmon/pfmon_smpl.c
> @@ -61,6 +61,8 @@ static pfmon_smpl_module_t *smpl_modules
> #endif
> #ifdef CONFIG_PFMON_I386_P6
> &detailed_i386_p6_smpl_module, /* must be first for P6 */
> +#endif
> +#ifdef CONFIG_PFMON_GEN_IA32
> &detailed_gen_ia32_smpl_module, /* must be last for I386 */
> #endif
> &inst_hist_smpl_module, /* works for any PMU model */
--
-Stephane
-
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