Re: Intel P6 vs P7 system call performance

From: Stephen Rothwell (sfr@canb.auug.org.au)
Date: Tue Dec 17 2002 - 23:40:23 EST

Hi Linus, Andrew,

On Tue, 17 Dec 2002 20:07:53 -0800 (PST) Linus Torvalds <torvalds@transmeta.com> wrote:
>
> Btw, on another tangent - Andrew Morton reports that APM is unhappy about
> the fact that the fast system call stuff required us to move the segments
> around a bit. That's probably because the APM code has the old APM segment
> numbers hardcoded somewhere, but I don't see where (I certainly knew about
> the segment number issue, and tried to update the cases I saw).

I looked at this yesterday and decided that it was OK as well.

> Debugging help would be appreciated, especially from somebody who knows
> the APM code.

It would help to know what "unhappy" means :-)

Does the following fix it for you? Untested, assumes cache lines are 32
bytes. 

-- 
Cheers,
Stephen Rothwell                    sfr@canb.auug.org.au
http://www.canb.auug.org.au/~sfr/

diff -ruN 2.5.52-200212181207/include/asm-i386/segment.h 2.5.52-200212181207-apm/include/asm-i386/segment.h
--- 2.5.52-200212181207/include/asm-i386/segment.h	2002-12-18 15:25:48.000000000 +1100
+++ 2.5.52-200212181207-apm/include/asm-i386/segment.h	2002-12-18 15:38:34.000000000 +1100
@@ -65,9 +65,9 @@
 #define GDT_ENTRY_APMBIOS_BASE		(GDT_ENTRY_KERNEL_BASE + 11)
 
 /*
- * The GDT has 23 entries but we pad it to cacheline boundary:
+ * The GDT has 25 entries but we pad it to cacheline boundary:
  */
-#define GDT_ENTRIES 24
+#define GDT_ENTRIES 28
 
 #define GDT_SIZE (GDT_ENTRIES * 8)
 
-
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