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From: Richard Kennedy <richard@rsk.demon.co.uk>
To: Ingo Molnar <mingo@elte.hu>
Cc: lkml <linux-kernel@vger.kernel.org>,
	the arch/x86 maintainers <x86@kernel.org>
Subject: [PATCH] x86: cacheline_align tss_struct
Date: Fri, 04 Jul 2008 13:56:16 +0100	[thread overview]
Message-ID: <1215176176.3144.5.camel@castor.localdomain> (raw)
In-Reply-To: <20080703113925.GA5594@elte.hu>

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@rsk.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);
 



  parent reply	other threads:[~2008-07-04 12:56 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-07-03 10:47 x86_64: tss_struct layout does not match comments !? Richard Kennedy
2008-07-03 11:39 ` Ingo Molnar
2008-07-03 11:57   ` Richard Kennedy
2008-07-04 12:56   ` Richard Kennedy [this message]
2008-07-04 14:48     ` [PATCH] x86: cacheline_align tss_struct Ingo Molnar

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