Messages in this thread | | | Date | Tue, 27 Jun 2006 07:32:04 -0700 | From | Stephane Eranian <> | Subject | Re: 2.6.17.1 new perfmon code base, libpfm, pfmon available |
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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 */
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