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From: Jeremy Fitzhardinge <jeremy@goop.org>
To: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: linux-kernel@vger.kernel.org, mingo@elte.hu, jens.axboe@oracle.com
Subject: Re: [PATCH 2/2] x86: replace BIO_VMERGE_BOUNDARY with BIOVEC_PHYS_MERGEABLE
Date: Mon, 27 Oct 2008 19:21:41 +1100	[thread overview]
Message-ID: <49057A15.7030007@goop.org> (raw)
In-Reply-To: <20081027125139I.fujita.tomonori@lab.ntt.co.jp>

FUJITA Tomonori wrote:
> The block layer always done the physical merge if possible. We don't
> provide any kernel parameter to disable it.
>
> The iommu_bio_merge parameter had been used to enable the virtual
> merge. As I wrote, the virtual merge feature was completely
> removed. Effectively, the iommu_bio_merge parameter is meaningless
> now.
>   

Under Xen, pages which appear to be pseudo-physically adjacent are not 
necessarily really physically adjacent.  We need to hook 
BIOVEC_PHYS_MERGEABLE to prevent the bio layer from inappropriately 
merging requests across non-contiguous page boundaries.

    J

  reply	other threads:[~2008-10-27  8:21 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-10-24  5:41 [PATCH] x86: remove dead BIO_VMERGE_BOUNDARY definition FUJITA Tomonori
2008-10-24 20:58 ` Jeremy Fitzhardinge
2008-10-27  4:42   ` FUJITA Tomonori
2008-10-24 20:59 ` [PATCH 1/2] bio: define __BIOVEC_PHYS_MERGEABLE Jeremy Fitzhardinge
2008-10-24 20:59 ` [PATCH 2/2] x86: replace BIO_VMERGE_BOUNDARY with BIOVEC_PHYS_MERGEABLE Jeremy Fitzhardinge
2008-10-27  3:52   ` FUJITA Tomonori
2008-10-27  8:21     ` Jeremy Fitzhardinge [this message]
2008-10-27  8:37       ` FUJITA Tomonori
2008-10-27  9:18         ` Jeremy Fitzhardinge
2008-10-27  9:36           ` FUJITA Tomonori
2008-10-27  9:41             ` Jens Axboe
2008-10-27 11:43               ` Jeremy Fitzhardinge
2008-10-27 11:57                 ` Jens Axboe
2008-10-28 23:06                   ` FUJITA Tomonori
2008-10-29  8:37                     ` Ingo Molnar
2008-10-29  9:24                       ` Jeremy Fitzhardinge
2008-10-29 10:51                         ` Ingo Molnar
2008-10-29 11:25                           ` Ingo Molnar
2008-10-29 11:27                             ` Jens Axboe
2008-10-29 11:30                               ` Ingo Molnar
2008-10-29 11:34                                 ` Jens Axboe
2008-10-29 11:55                                   ` FUJITA Tomonori
2008-10-29 12:12                                 ` Jeremy Fitzhardinge
2008-10-29 13:03                                   ` Ingo Molnar
2008-10-29 13:06                                     ` Jeremy Fitzhardinge
2008-10-29 13:06                                       ` Jens Axboe
2008-10-29  9:27                     ` Jens Axboe

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