2.2.20pre1: Problems with SMP

2.2.20pre1: Problems with SMP

[Shane Wegner]

Hi,

Just booted up 2.2.20pre1 and am getting some funny
results.  The system boots but is very slow.  Every few
seconds I get:
Stuck on TLB IPI wait (CPU#0)

Booting vanilla 2.2.19 works fine.  The machine is an
Intel Pentium III 850MHZ on an Abit VP6 board.  If any
further information is needed, let me know.

Regards,
Shane

-- 
Shane Wegner: shane@cm.nu
              http://www.cm.nu/~shane/
PGP:          1024D/FFE3035D
              A0ED DAC4 77EC D674 5487
              5B5C 4F89 9A4E FFE3 035D

Re: 2.2.20pre1: Problems with SMP

[Alan Cox]

> Just booted up 2.2.20pre1 and am getting some funny
> results.  The system boots but is very slow.  Every few
> seconds I get:
> Stuck on TLB IPI wait (CPU#0)
> 
> Booting vanilla 2.2.19 works fine.  The machine is an
> Intel Pentium III 850MHZ on an Abit VP6 board.  If any
> further information is needed, let me know.

Can you back out the change to io_apic.c and tell me if that fixes it. If so
let Johannes Erdfelt and I know.

Re: 2.2.20pre1: Problems with SMP

[Shane Wegner]

On Mon, May 07, 2001 at 11:36:49AM +0100, Alan Cox wrote:
> > Just booted up 2.2.20pre1 and am getting some funny
> > results.  The system boots but is very slow.  Every few
> > seconds I get:
> > Stuck on TLB IPI wait (CPU#0)
> > 
> > Booting vanilla 2.2.19 works fine.  The machine is an
> > Intel Pentium III 850MHZ on an Abit VP6 board.  If any
> > further information is needed, let me know.
> 
> Can you back out the change to io_apic.c and tell me if that fixes it. If so
> let Johannes Erdfelt and I know.

That does indeed correct the problem.  2.2.20pre1 now works
as expected.

Shane

-- 
Shane Wegner: shane@cm.nu
              http://www.cm.nu/~shane/
PGP:          1024D/FFE3035D
              A0ED DAC4 77EC D674 5487
              5B5C 4F89 9A4E FFE3 035D

Re: 2.2.20pre1: Problems with SMP

[Johannes Erdfelt]

On Mon, May 07, 2001, Shane Wegner <shane@cm.nu> wrote:
> On Mon, May 07, 2001 at 11:36:49AM +0100, Alan Cox wrote:
> > > Just booted up 2.2.20pre1 and am getting some funny
> > > results.  The system boots but is very slow.  Every few
> > > seconds I get:
> > > Stuck on TLB IPI wait (CPU#0)
> > > 
> > > Booting vanilla 2.2.19 works fine.  The machine is an
> > > Intel Pentium III 850MHZ on an Abit VP6 board.  If any
> > > further information is needed, let me know.
> > 
> > Can you back out the change to io_apic.c and tell me if that fixes it. If so
> > let Johannes Erdfelt and I know.
> 
> That does indeed correct the problem.  2.2.20pre1 now works
> as expected.

Hmm, that uses a VIA based chipset. I didn't know they did SMP yet. Does
2.4 work on this system?

JE

Re: 2.2.20pre1: Problems with SMP

[Shane Wegner]

On Mon, May 07, 2001 at 11:02:50AM -0700, Johannes Erdfelt wrote:
> On Mon, May 07, 2001, Shane Wegner <shane@cm.nu> wrote:
> > 
> > That does indeed correct the problem.  2.2.20pre1 now works
> > as expected.
> 
> Hmm, that uses a VIA based chipset. I didn't know they did SMP yet. Does
> 2.4 work on this system?

The last 2.4 kernel I tried was 2.4.3 I believe and it
worked fine more or less.  I haven't tried any later 2.4
kernels yet.

Shane


-- 
Shane Wegner: shane@cm.nu
              http://www.cm.nu/~shane/
PGP:          1024D/FFE3035D
              A0ED DAC4 77EC D674 5487
              5B5C 4F89 9A4E FFE3 035D

Re: 2.2.20pre1: Problems with SMP

[Johannes Erdfelt]

On Mon, May 07, 2001, Shane Wegner <shane@cm.nu> wrote:
> On Mon, May 07, 2001 at 11:02:50AM -0700, Johannes Erdfelt wrote:
> > On Mon, May 07, 2001, Shane Wegner <shane@cm.nu> wrote:
> > > 
> > > That does indeed correct the problem.  2.2.20pre1 now works
> > > as expected.
> > 
> > Hmm, that uses a VIA based chipset. I didn't know they did SMP yet. Does
> > 2.4 work on this system?
> 
> The last 2.4 kernel I tried was 2.4.3 I believe and it
> worked fine more or less.  I haven't tried any later 2.4
> kernels yet.

That's fine. The I/O APIC code is different and I tried to make the 2.2
code work like the 2.4 code with minimal changes. However, the changes
aren't trivial. I'll take a quick look and see if I can find any more
significant differences.

I wonder if I have a VIA board laying around here.

JE

Re: 2.2.20pre1: Problems with SMP

[Johannes Erdfelt]

On Mon, May 07, 2001, Shane Wegner <shane@cm.nu> wrote:
> On Mon, May 07, 2001 at 11:02:50AM -0700, Johannes Erdfelt wrote:
> > On Mon, May 07, 2001, Shane Wegner <shane@cm.nu> wrote:
> > > 
> > > That does indeed correct the problem.  2.2.20pre1 now works
> > > as expected.
> > 
> > Hmm, that uses a VIA based chipset. I didn't know they did SMP yet. Does
> > 2.4 work on this system?
> 
> The last 2.4 kernel I tried was 2.4.3 I believe and it
> worked fine more or less.  I haven't tried any later 2.4
> kernels yet.

Could you try this patch? It applies on top of 2.2.20pre1

It also cleans up a couple of comments

JE

--- arch/i386/kernel/io_apic.c.old	Wed May 16 12:48:03 2001
+++ arch/i386/kernel/io_apic.c	Wed May 16 12:55:30 2001
@@ -204,6 +204,8 @@
 /*
  * We disable IO-APIC IRQs by setting their 'destination CPU mask' to
  * zero. Trick by Ramesh Nalluri.
+ * Not anymore. This causes problems on some IO-APIC's, notably AMD 760MP's
+ * So we do it a more 2.4 kind of way now which should be safer -jerdfelt
  */
 DO_ACTION( mask,    0, |= 0x00010000, io_apic_sync(entry->apic))/* mask = 1 */
 DO_ACTION( unmask,  0, &= 0xfffeffff, )				/* mask = 0 */
@@ -646,8 +648,8 @@
 
 		entry.delivery_mode = dest_LowestPrio;
 		entry.dest_mode = 1;			/* logical delivery */
-		entry.mask = 0;				/* enable IRQ */
-		entry.dest.logical.logical_dest = 0xff;	/* but no route */
+		entry.mask = 1;				/* disable IRQ */
+		entry.dest.logical.logical_dest = 0xff;
 
 		idx = find_irq_entry(apic,pin,mp_INT);
 		if (idx == -1) {

Re: 2.2.20pre1: Problems with SMP

[Shane Wegner]

On Wed, May 16, 2001 at 12:56:55PM -0700, Johannes Erdfelt wrote:
> 
> Could you try this patch? It applies on top of 2.2.20pre1
> 
> It also cleans up a couple of comments

That fixes it alright.

Shane

-- 
Shane Wegner: shane@cm.nu
              http://www.cm.nu/~shane/
PGP:          1024D/FFE3035D
              A0ED DAC4 77EC D674 5487
              5B5C 4F89 9A4E FFE3 035D

Re: 2.2.20pre1: Problems with SMP

[Johannes Erdfelt]

On Wed, May 16, 2001, Shane Wegner <shane@cm.nu> wrote:
> On Wed, May 16, 2001 at 12:56:55PM -0700, Johannes Erdfelt wrote:
> > Could you try this patch? It applies on top of 2.2.20pre1
> > 
> > It also cleans up a couple of comments
> 
> That fixes it alright.

Excellent. Alan, could you apply the patch to 2.2.20pre2?

JE