From: Christoph Lameter <clameter@sgi.com>
To: Jens Axboe <jens.axboe@oracle.com>
Cc: Dmitry Monakhov <dmonakhov@sw.ru>,
torvalds@linux-foundation.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org, Christoph Hellwig <hch@lst.de>,
Mel Gorman <mel@skynet.ie>,
William Lee Irwin III <wli@holomorphy.com>,
David Chinner <dgc@sgi.com>, Badari Pulavarty <pbadari@gmail.com>,
Maxim Levitsky <maximlevitsky@gmail.com>,
Fengguang Wu <fengguang.wu@gmail.com>,
swin wang <wangswin@gmail.com>,
totty.lu@gmail.com, "H. Peter Anvin" <hpa@zytor.com>,
joern@lazybastard.org,
"Eric W. Biederman" <ebiederm@xmission.com>
Subject: Re: [11/36] Use page_cache_xxx in fs/buffer.c
Date: Fri, 31 Aug 2007 00:33:30 -0700 (PDT) [thread overview]
Message-ID: <Pine.LNX.4.64.0708310028160.14632@schroedinger.engr.sgi.com> (raw)
In-Reply-To: <20070831072611.GK29452@kernel.dk>
On Fri, 31 Aug 2007, Jens Axboe wrote:
> > A DMA boundary cannot be crossed AFAIK. The compound pages are aligned to
> > the power of two boundaries and the page allocator will not create pages
> > that cross the zone boundaries.
>
> With a 64k page and a dma boundary of 0x7fff, that's two segments.
Ok so DMA memory restrictions not conforming to the DMA zones? The
example is a bit weird. DMA only to the first 32k of memory? If the limit
would be higher like 16MB then we would not have an issue. Is there really
a device that can only do I/O to the first 32k of memory?
How do we split that up today? We could add processing to submit_bio to
check for the boundary and create two bios.
> > submit_bh() is used to submit a single buffer and I think that was our
> > main concern here.
>
> And how large can that be?
As large as mkxxxfs allowed it to be. For XFS and extX with the current
patchset 32k is the limit (64k with the fixes to ext2) but a new
filesystem could theoretically use a larger blocksize.
next prev parent reply other threads:[~2007-08-31 7:33 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20070828190551.415127746@sgi.com>
[not found] ` <20070828190735.292638294@sgi.com>
2007-08-30 0:11 ` [31/36] Large Blocksize: Core piece Mingming Cao
2007-08-30 0:12 ` Christoph Lameter
2007-08-30 0:47 ` [RFC 1/4] Large Blocksize support for Ext2/3/4 Mingming Cao
2007-08-30 0:59 ` Christoph Lameter
2007-09-01 0:01 ` Mingming Cao
2007-09-01 0:12 ` [RFC 1/2] JBD: slab management support for large block(>8k) Mingming Cao
2007-09-01 18:39 ` Christoph Hellwig
2007-09-02 11:40 ` Christoph Lameter
2007-09-02 15:28 ` Christoph Hellwig
2007-09-03 7:55 ` Christoph Lameter
2007-09-03 13:40 ` Christoph Hellwig
2007-09-03 19:31 ` Christoph Lameter
2007-09-03 19:33 ` Christoph Hellwig
2007-09-14 18:53 ` [PATCH] JBD slab cleanups Mingming Cao
2007-09-14 18:58 ` Christoph Lameter
2007-09-17 19:29 ` Mingming Cao
2007-09-17 19:34 ` Christoph Hellwig
2007-09-17 22:01 ` Badari Pulavarty
2007-09-17 22:57 ` Mingming Cao
2007-09-18 9:04 ` Christoph Hellwig
2007-09-18 16:35 ` Mingming Cao
2007-09-18 18:04 ` Dave Kleikamp
2007-09-19 1:00 ` Mingming Cao
2007-09-19 2:19 ` Andrew Morton
2007-09-19 19:15 ` Mingming Cao
2007-09-19 19:22 ` [PATCH] JBD: use GFP_NOFS in kmalloc Mingming Cao
2007-09-19 21:34 ` Andrew Morton
2007-09-19 21:55 ` Mingming Cao
2007-09-20 4:25 ` Andreas Dilger
2007-09-19 19:26 ` [PATCH] JBD slab cleanups Dave Kleikamp
2007-09-19 19:28 ` Dave Kleikamp
2007-09-19 20:47 ` Mingming Cao
2007-09-19 19:48 ` Andreas Dilger
2007-09-19 22:03 ` Mingming Cao
2007-09-01 0:12 ` [RFC 2/2] JBD: blocks reservation fix for large block support Mingming Cao
2007-08-30 0:47 ` [RFC 2/4]ext2: fix rec_len overflow with 64KB block size Mingming Cao
[not found] ` <20070828190730.220393749@sgi.com>
2007-08-30 9:20 ` [11/36] Use page_cache_xxx in fs/buffer.c Dmitry Monakhov
2007-08-30 18:14 ` Christoph Lameter
2007-08-31 1:47 ` Christoph Lameter
2007-08-31 6:56 ` Jens Axboe
2007-08-31 7:03 ` Christoph Lameter
2007-08-31 7:11 ` Jens Axboe
2007-08-31 7:17 ` Christoph Lameter
2007-08-31 7:26 ` Jens Axboe
2007-08-31 7:33 ` Christoph Lameter [this message]
2007-08-31 7:43 ` Jens Axboe
2007-08-31 7:52 ` Christoph Lameter
2007-08-31 8:12 ` Jens Axboe
2007-08-31 15:22 ` Christoph Lameter
2007-08-31 16:35 ` Jörn Engel
2007-08-31 19:00 ` Jens Axboe
2007-08-31 8:36 ` Dmitry Monakhov
2007-08-31 15:28 ` Christoph Lameter
[not found] ` <20070828192034.GA13883@lst.de>
[not found] ` <Pine.LNX.4.64.0708281254070.16473@schroedinger.engr.sgi.com>
2007-09-01 1:11 ` [00/36] Large Blocksize Support V6 Christoph Lameter
2007-09-01 19:17 ` Peter Zijlstra
2007-09-02 11:44 ` Christoph Lameter
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