In-Reply-To: <[email protected]>
On Mon, 26 Jun 2006 15:37:17 -0700, Stephane Eranian wrote:
> > 32-bit works great. Unfortunately, pfmon is far too limited for serious kernel
> > monitoring AFAICT. E.g. you can't select edge counting instead of cycle
> > counting. So you can count how many clock cycles were spent with interrupts
>
> I put in an option to enable this mode, do pfmon --help. I think it's called
> edge-mask.
Silly me, I was reading the documentation, which doesn't cover this. :)
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:
$ 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:
$ pfmon --smpl-module=inst-hist -ecpu_clk_unhalted -k --short-smpl-period=100000 --resolve-addr --system-wide -t 10
only kernel symbols are resolved in system-wide mode
<session to end in 10 seconds>
# counts %self %cum code address
# counts %self %cum code address
And here's what it took to get everything working on Pentium II (seems OK, not
thoroughly tested:)
_
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 */
--
Chuck
"You can't read a newspaper if you can't read." --George W. Bush
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