From: Mikulas Patocka <mpatocka@redhat.com>
To: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: jens.axboe@oracle.com, linux-kernel@vger.kernel.org,
linux-scsi@vger.kernel.org, davem@davemloft.net,
linux-parisc@vger.kernel.org
Subject: Re: [PATCH] block: fix q->max_segment_size checking in blk_recalc_rq_segments about VMERGE
Date: Tue, 15 Jul 2008 10:37:58 -0400 (EDT) [thread overview]
Message-ID: <Pine.LNX.4.64.0807151033040.25390@devserv.devel.redhat.com> (raw)
In-Reply-To: <20080715231956A.fujita.tomonori@lab.ntt.co.jp>
>>> This bug could happen on alpha, parisc, and sparc, which use VMERGE.
>>
>> Parisc doesn't use virtual merge accounting (there is variable for it but
>> it's always 0).
>
> Hmm, really? Looks like PARISC IOMMUs (ccio-dma.c and sba_iomm.c) set
> parisc_vmerge_boundary (CC'ed PARISC mailing list).
That's right, I looked only at arch and include.
>> On sparc64 it is broken anyway with or without your patch.
>
> Yeah, we need to modify SPARC64 IOMMU code (I'm not sure that it's
> worth). Right now, the best fix is setting BIO_VMERGE_BOUNDARY to 0.
Even if we fix it now, the question is: how long it will stay fixed? Until
someone makes another change to struct device that restricts boundaries on
some wacky hardware.
Mikulas
>> And alpha alone doesn't justify substantial code bloat in generic block
>> layer. So I propose this patch to drop it at all.
>
> Jens, what do you think about removing VMERGE code?
>
next prev parent reply other threads:[~2008-07-15 14:37 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-07-15 10:44 [PATCH] block: fix q->max_segment_size checking in blk_recalc_rq_segments about VMERGE FUJITA Tomonori
2008-07-15 13:37 ` Mikulas Patocka
2008-07-15 14:20 ` FUJITA Tomonori
2008-07-15 14:37 ` Mikulas Patocka [this message]
2008-07-15 15:30 ` FUJITA Tomonori
2008-07-15 15:46 ` Mikulas Patocka
2008-07-16 0:34 ` FUJITA Tomonori
2008-07-16 18:02 ` Mikulas Patocka
2008-07-17 4:14 ` FUJITA Tomonori
2008-07-17 11:50 ` Mikulas Patocka
2008-07-17 13:18 ` FUJITA Tomonori
2008-07-17 13:27 ` Boaz Harrosh
2008-07-17 13:56 ` James Bottomley
2008-07-19 7:28 ` David Miller
2008-07-20 1:45 ` Mikulas Patocka
2008-07-20 2:17 ` James Bottomley
2008-07-20 4:07 ` David Miller
2008-07-20 14:52 ` James Bottomley
2008-07-20 17:23 ` David Miller
2008-07-20 17:33 ` James Bottomley
2008-07-24 15:07 ` Mikulas Patocka
2008-07-24 15:28 ` James Bottomley
2008-07-24 16:34 ` Mikulas Patocka
2008-07-24 16:52 ` James Bottomley
2008-07-24 21:49 ` Mikulas Patocka
2008-07-24 21:53 ` David Miller
2008-07-25 3:47 ` James Bottomley
2008-07-25 5:21 ` David Miller
2008-07-25 2:26 ` FUJITA Tomonori
2008-07-25 2:40 ` [PATCH] block: fix q->max_segment_size checking in blk_recalc_rq_segments John David Anglin
2008-07-20 5:54 ` [PATCH] block: fix q->max_segment_size checking in blk_recalc_rq_segments about VMERGE David Miller
2008-07-15 14:50 ` James Bottomley
2008-07-15 15:24 ` Mikulas Patocka
2008-07-15 15:41 ` James Bottomley
2008-07-15 15:58 ` Mikulas Patocka
2008-07-15 16:07 ` James Bottomley
2008-07-15 16:20 ` Mikulas Patocka
2008-07-15 16:36 ` James Bottomley
2008-07-15 21:50 ` Mikulas Patocka
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