linux-kernel - [PATCH] x86: cacheline_align tss

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Date:	Fri, 04 Jul 2008 13:56:16 +0100
From:	Richard Kennedy <richard@....demon.co.uk>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	lkml <linux-kernel@...r.kernel.org>,
	the arch/x86 maintainers <x86@...nel.org>
Subject: [PATCH] x86: cacheline_align tss_struct

The manual padding to align on cacheline size only worked in 32 bit
In 64 bit the structure was not aligned and contained wasted space.
    
use the compiler ____cachline_aligned to save space & properly align
this structure.
    
x86_64_default size goes from 9136 -> 8960
x86_64_AMD     size goes from 9136 -> 8896
    
    
Signed-off-by: Richard Kennedy <richard@....demon.co.uk>
---

Hi Ingo
here's the patch.
built & running on 2.6.26-rc8.

Richard



diff --git a/include/asm-x86/processor.h b/include/asm-x86/processor.h
index 5591052..4ab2ede 100644
--- a/include/asm-x86/processor.h
+++ b/include/asm-x86/processor.h
@@ -263,15 +263,11 @@ struct tss_struct {
 	struct thread_struct	*io_bitmap_owner;
 
 	/*
-	 * Pad the TSS to be cacheline-aligned (size is 0x100):
-	 */
-	unsigned long		__cacheline_filler[35];
-	/*
 	 * .. and then another 0x100 bytes for the emergency kernel stack:
 	 */
 	unsigned long		stack[64];
 
-} __attribute__((packed));
+} ____cacheline_aligned;
 
 DECLARE_PER_CPU(struct tss_struct, init_tss);
 


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