linux-kernel - Re: [discuss] Re: [PATCH for 2.6.18] [2/8] x86_64: On Intel systems when CPU has C3 don't use TSC

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Message-Id: <1154472761.3316.8.camel@localhost.portugal>
Date:	Tue, 01 Aug 2006 23:52:41 +0100
From:	Sergio Monteiro Basto <sergio@...giomb.no-ip.org>
To:	Andi Kleen <ak@...e.de>
Cc:	discuss@...-64.org, torvalds@...l.org,
	linux-kernel@...r.kernel.org,
	"Siddha, Suresh B" <suresh.b.siddha@...el.com>
Subject: Re: [discuss] Re: [PATCH for 2.6.18] [2/8] x86_64: On Intel
	systems when CPU has C3 don't use TSC

ok , here it is dmesg version 16 
I just add this printtk 
--- linux-2.6.17.x86_64/arch/x86_64/kernel/time.c.orig	2006-08-01
01:34:29.000000000 +0100
+++ linux-2.6.17.x86_64/arch/x86_64/kernel/time.c	2006-08-01 23:31:29.000000000 +0100
@@ -959,6 +959,9 @@ __cpuinit int unsynchronized_tsc(void)
 	   multi node systems */
  	if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) {
 #ifdef CONFIG_ACPI
+		printk(KERN_INFO "time.c:SB acpi_fadt.length=%d, acpi_fadt.plvl3_lat=%d unsynchronized_tsc=%d\n",
+					            acpi_fadt.length, acpi_fadt.plvl3_lat,(acpi_fadt.length > 0 && acpi_fadt.plvl3_lat <
+									100) );
 		/* But TSC doesn't tick in C3 so don't use it there */
 		if (acpi_fadt.length > 0 && acpi_fadt.plvl3_lat < 100)
 			return 1;

but this time the function unsynchronized_tsc was just call one time.

time.c:SB acpi_fadt.length=0, acpi_fadt.plvl3_lat=0 unsynchronized_tsc=0

The patch works like I have use boot parameter notsc, which is better.
Now I don't need any parameter to boot.

Big Thanks 

On Wed, 2006-08-02 at 00:21 +0200, Andi Kleen wrote:
> On Wednesday 02 August 2006 00:06, Sergio Monteiro Basto wrote:
> > On Tue, 2006-08-01 at 23:56 +0200, Andi Kleen wrote:
> > > Lost timer ticks print a rip. Do you have some samples?
> 
> Can you send dmesg with the following patch applied too?
> 
> cc'ing Suresh because he might have an explanation too then.
> 
> -Andi
> 
> Index: linux-2.6.18-rc3-work/arch/x86_64/kernel/smpboot.c
> ===================================================================
> --- linux-2.6.18-rc3-work.orig/arch/x86_64/kernel/smpboot.c
> +++ linux-2.6.18-rc3-work/arch/x86_64/kernel/smpboot.c
> @@ -345,7 +345,7 @@ static void __cpuinit tsc_sync_wait(void
>  	 * mess up a possible perfect synchronization with a
>  	 * not-quite-perfect algorithm.
>  	 */
> -	if (notscsync || !cpu_has_tsc || !unsynchronized_tsc())
> +	if (0 && (notscsync || !cpu_has_tsc || !unsynchronized_tsc()))
>  		return;
>  	sync_tsc(0);
>  }
-- 
Sérgio M. B.

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