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From: Tejun Heo <htejun@gmail.com>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>,
	James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Mark Mason <mason@postdiluvian.org>,
	linux-ide@vger.kernel.org, jgarzik@pobox.com,
	Jens Axboe <jens.axboe@oracle.com>
Subject: [PATCH] scsi: align shost->hostdata to cacheline
Date: Thu, 14 Feb 2008 18:48:01 +0900	[thread overview]
Message-ID: <47B40E51.3060002@gmail.com> (raw)
In-Reply-To: <47B3AFDC.5040605@gmail.com>

shost->hostdata can contain arbitrary data including DMA target
buffers.  Align it to cacheline.

Signed-off-by: Tejun Heo <htejun@gmail.com>
---
James, what do you think?

 include/scsi/scsi_host.h |    8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index 5c58d59..3876d24 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -663,12 +663,10 @@ struct Scsi_Host {
 	void *shost_data;
 
 	/*
-	 * We should ensure that this is aligned, both for better performance
-	 * and also because some compilers (m68k) don't automatically force
-	 * alignment to a long boundary.
+	 * Used for storage of host specific stuff.  As it may contain
+	 * arbitrary data, align it to cacheline.
 	 */
-	unsigned long hostdata[0]  /* Used for storage of host specific stuff */
-		__attribute__ ((aligned (sizeof(unsigned long))));
+	unsigned long hostdata[0] ____cacheline_aligned;
 };
 
 #define		class_to_shost(d)	\

  parent reply	other threads:[~2008-02-14  9:48 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-02-12 18:02 libata/sata_sil24 cache alignment problem? Mark Mason
2008-02-12 22:12 ` Alan Cox
2008-02-12 23:36   ` James Bottomley
2008-02-13  2:13     ` Alan Cox
2008-02-13  2:32       ` James Bottomley
2008-02-13 18:47   ` Mark Mason
2008-02-13 20:21     ` Alan Cox
2008-02-13 21:25       ` Mark Mason
2008-02-14  0:21         ` Alan Cox
2008-02-14  3:05           ` Tejun Heo
2008-02-14  9:44             ` [PATCH] libata: align ap->sector_buf to cacheline Tejun Heo
2008-02-14  9:48             ` Tejun Heo [this message]
2008-02-14 15:05               ` [PATCH] scsi: align shost->hostdata " James Bottomley
2008-02-14 22:49                 ` Tejun Heo
2008-02-15 18:57                   ` James Bottomley
2008-02-21  2:32                     ` Tejun Heo
2008-02-13 18:51   ` libata/sata_sil24 cache alignment problem? Mark Mason
2008-02-12 23:25 ` Thomas Evans

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