linux-kernel - Re: 2.6.22-rc7: known regressions with patches

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Message-Id: <200707040138.13538.ak@suse.de>
Date:	Wed, 4 Jul 2007 01:38:13 +0200
From:	Andi Kleen <ak@...e.de>
To:	Björn Steinbrink <B.Steinbrink@....de>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Michal Piotrowski <michal.k.k.piotrowski@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Stephane Eranian <eranian@....hp.com>
Subject: Re: 2.6.22-rc7: known regressions with patches

On Wednesday 04 July 2007 00:12:10 Björn Steinbrink wrote:
> On 2007.07.03 14:42:25 -0700, Linus Torvalds wrote:
> > 
> > 
> > On Tue, 3 Jul 2007, Bj?rn Steinbrink wrote:
> > > Andi said that one of the regression fixes wasn't critical for .22 and
> > > that he wants to do a stopgap for the other regression (my patch
> > > sucked), reverting the code to the .21 version. So you can drop the
> > > patches and/or me here.
> > 
> > Can you say which patch should be reverted. This thing really shouldn't 
> > have gone on this long, I would have hopef we had the oprofile thing 
> > sorted out already..
> 
> That would be commit 09198e68501a7e34737cd9264d266f42429abcdc, for which
> there are already a few fixes in your tree. Andi, did you intent to
> fully revert that, or just certain parts of it?

Just two functions, but in a different file. Here's the patch.

Linus, also what about the revert of the HPET reservation? That would
fix a clear regression too.

-Andi

Revert perfctr reservation to 2.6.21 state

With this change it works again when the nmi watchdog is disabled.

Signed-off-by: Andi Kleen <ak@...e.de>

Index: linux/arch/i386/kernel/cpu/perfctr-watchdog.c
===================================================================
--- linux.orig/arch/i386/kernel/cpu/perfctr-watchdog.c
+++ linux/arch/i386/kernel/cpu/perfctr-watchdog.c
@@ -55,14 +55,45 @@ static DEFINE_PER_CPU(struct nmi_watchdo
 /* converts an msr to an appropriate reservation bit */
 static inline unsigned int nmi_perfctr_msr_to_bit(unsigned int msr)
 {
-	return wd_ops ? msr - wd_ops->perfctr : 0;
+	/* returns the bit offset of the performance counter register */
+	switch (boot_cpu_data.x86_vendor) {
+	case X86_VENDOR_AMD:
+		return (msr - MSR_K7_PERFCTR0);
+	case X86_VENDOR_INTEL:
+		if (cpu_has(&boot_cpu_data, X86_FEATURE_ARCH_PERFMON))
+			return (msr - MSR_ARCH_PERFMON_PERFCTR0);
+
+		switch (boot_cpu_data.x86) {
+		case 6:
+			return (msr - MSR_P6_PERFCTR0);
+		case 15:
+			return (msr - MSR_P4_BPU_PERFCTR0);
+		}
+	}
+	return 0;
 }
 
 /* converts an msr to an appropriate reservation bit */
 /* returns the bit offset of the event selection register */
 static inline unsigned int nmi_evntsel_msr_to_bit(unsigned int msr)
 {
-	return wd_ops ? msr - wd_ops->evntsel : 0;
+	/* returns the bit offset of the event selection register */
+	switch (boot_cpu_data.x86_vendor) {
+	case X86_VENDOR_AMD:
+		return (msr - MSR_K7_EVNTSEL0);
+	case X86_VENDOR_INTEL:
+		if (cpu_has(&boot_cpu_data, X86_FEATURE_ARCH_PERFMON))
+			return (msr - MSR_ARCH_PERFMON_EVENTSEL0);
+
+		switch (boot_cpu_data.x86) {
+		case 6:
+			return (msr - MSR_P6_EVNTSEL0);
+		case 15:
+			return (msr - MSR_P4_BSU_ESCR0);
+		}
+	}
+	return 0;
+
 }
 
 /* checks for a bit availability (hack for oprofile) */
-
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