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From: Christoph Hellwig <hch@lst.de>
To: Ming Lei <ming.lei@redhat.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>,
	Christoph Lameter <cl@linux.com>,
	Pekka Enberg <penberg@kernel.org>,
	David Rientjes <rientjes@google.com>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Ming Lei <tom.leiming@gmail.com>,
	linux-block <linux-block@vger.kernel.org>,
	linux-mm <linux-mm@kvack.org>,
	Linux FS Devel <linux-fsdevel@vger.kernel.org>,
	"open list:XFS FILESYSTEM" <linux-xfs@vger.kernel.org>,
	Dave Chinner <dchinner@redhat.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>
Subject: Re: block: DMA alignment of IO buffer allocated from slab
Date: Thu, 20 Sep 2018 08:32:26 +0200	[thread overview]
Message-ID: <20180920063226.GC12913@lst.de> (raw)
In-Reply-To: <20180920012836.GA27645@ming.t460p>

On Thu, Sep 20, 2018 at 09:28:37AM +0800, Ming Lei wrote:
> > has e.g. PAGE_SIZE alignment requirement (this would likely imply that
> > it's sector size is also not 512 I guess)?
> 
> Yeah, that can be true if one controller has 4k-byte sector size, also
> its DMA alignment is 4K. But there shouldn't be cases in which the two
> doesn't match.

The general block storage worlds is that devices always need to have
an alignment requirement <= minimum LBAs size.  If they don't they'll
need to bounce buffer (in the driver!).

  parent reply	other threads:[~2018-09-20  6:32 UTC|newest]

Thread overview: 59+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-19  9:15 block: DMA alignment of IO buffer allocated from slab Ming Lei
2018-09-19  9:41 ` Vitaly Kuznetsov
2018-09-19  9:41   ` Vitaly Kuznetsov
2018-09-19  9:41   ` Vitaly Kuznetsov
2018-09-19 10:02   ` Ming Lei
2018-09-19 10:02     ` Ming Lei
2018-09-19 11:15     ` Vitaly Kuznetsov
2018-09-19 11:15       ` Vitaly Kuznetsov
2018-09-19 11:15       ` Vitaly Kuznetsov
2018-09-20  1:28       ` Ming Lei
2018-09-20  3:59         ` Yang Shi
2018-09-20  6:32         ` Christoph Hellwig [this message]
2018-09-20  6:31 ` Christoph Hellwig
2018-09-21 13:04   ` Vitaly Kuznetsov
2018-09-21 13:04     ` Vitaly Kuznetsov
2018-09-21 13:04     ` Vitaly Kuznetsov
2018-09-21 13:05     ` Christoph Hellwig
2018-09-21 15:00       ` Jens Axboe
2018-09-24 16:06       ` Christopher Lameter
2018-09-24 17:49         ` Jens Axboe
2018-09-24 18:00           ` Christopher Lameter
2018-09-24 18:09             ` Jens Axboe
2018-09-25  7:49               ` Dave Chinner
2018-09-25 15:44                 ` Jens Axboe
2018-09-25 21:04                 ` Matthew Wilcox
2018-09-23 22:42     ` Ming Lei
2018-09-24  9:46       ` Andrey Ryabinin
2018-09-24 14:19         ` Bart Van Assche
2018-09-24 14:43           ` Andrey Ryabinin
2018-09-24 14:43             ` Andrey Ryabinin
2018-09-24 15:08             ` Bart Van Assche
2018-09-24 15:08               ` Bart Van Assche
2018-09-24 15:52               ` Andrey Ryabinin
2018-09-24 15:58                 ` Bart Van Assche
2018-09-24 15:58                   ` Bart Van Assche
2018-09-24 16:07                   ` Andrey Ryabinin
2018-09-24 16:19                     ` Bart Van Assche
2018-09-24 16:19                       ` Bart Van Assche
2018-09-24 16:47                       ` Christopher Lameter
2018-09-24 18:57                       ` Matthew Wilcox
2018-09-24 19:56                         ` Bart Van Assche
2018-09-24 19:56                           ` Bart Van Assche
2018-09-24 20:41                           ` Matthew Wilcox
2018-09-24 20:54                             ` Bart Van Assche
2018-09-24 20:54                               ` Bart Van Assche
2018-09-24 21:09                               ` Matthew Wilcox
2018-09-25  0:16                         ` Ming Lei
2018-09-25  3:28                           ` Matthew Wilcox
2018-09-25  4:10                             ` Bart Van Assche
2018-09-25  4:44                               ` Matthew Wilcox
2018-09-25  6:55                                 ` Ming Lei
2018-09-24 15:17           ` Christopher Lameter
2018-09-25  0:20             ` Ming Lei
2018-09-20 14:07 ` Bart Van Assche
2018-09-21  1:56 ` Dave Chinner
2018-09-21  1:56   ` Dave Chinner
2018-09-21  7:08   ` Christoph Hellwig
2018-09-21  7:25     ` Ming Lei
2018-09-21 14:59       ` Jens Axboe

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