[PATCH] Use of Performance Monitoring Counters based on Model number

[PATCH] Use of Performance Monitoring Counters based on Model number

[Pallipadi, Venkatesh]

Attached is a small patch to make Linux kernel use of performance
monitoring MSRs based on known processor models. Future processor
implementation models may not support the same MSR layout.

Please apply.

Thanks,
-Venkatesh




--- linux-2.5.72-monitor/arch/i386/kernel/nmi.c.org	2003-06-16
21:20:02.000000000 -0700
+++ linux-2.5.72-monitor/arch/i386/kernel/nmi.c	2003-06-20
15:47:29.000000000 -0700
@@ -157,9 +157,15 @@
 	case X86_VENDOR_INTEL:
 		switch (boot_cpu_data.x86) {
 		case 6:
+			if (boot_cpu_data.x86_model > 0xd)
+				break;
+
 			wrmsr(MSR_P6_EVNTSEL0, 0, 0);
 			break;
 		case 15:
+			if (boot_cpu_data.x86_model > 0x3)
+				break;
+
 			wrmsr(MSR_P4_IQ_CCCR0, 0, 0);
 			wrmsr(MSR_P4_CRU_ESCR0, 0, 0);
 			break;
@@ -324,9 +338,15 @@
 	case X86_VENDOR_INTEL:
 		switch (boot_cpu_data.x86) {
 		case 6:
+			if (boot_cpu_data.x86_model > 0xd)
+				return;
+
 			setup_p6_watchdog();
 			break;
 		case 15:
+			if (boot_cpu_data.x86_model > 0x3)
+				return;
+
 			if (!setup_p4_watchdog())
 				return;
 			break;

Re: [PATCH] Use of Performance Monitoring Counters based on Model number

[John Levon]

On Wed, Jul 16, 2003 at 10:07:49AM -0700, Pallipadi, Venkatesh wrote:

> Attached is a small patch to make Linux kernel use of performance
> monitoring MSRs based on known processor models. Future processor
> implementation models may not support the same MSR layout.

If you're going to do this you should fix up arch/i386/oprofile/ to
error out similarly at least

regards
john

Re: [PATCH] Use of Performance Monitoring Counters based on Model number

[Dave Jones]

On Wed, Jul 16, 2003 at 06:19:56PM +0100, John Levon wrote:

 > > Attached is a small patch to make Linux kernel use of performance
 > > monitoring MSRs based on known processor models. Future processor
 > > implementation models may not support the same MSR layout.
 > If you're going to do this you should fix up arch/i386/oprofile/ to
 > error out similarly at least

It'd also be nice to let the user know why things aren't working
instead of silent failure. A simple

	printk (KERN_INFO "Performance counter support for this CPU not yet added.\n");

Should do the trick.

		Dave