From: Christoph Hellwig <hch@lst.de>
To: Matthew Wilcox <willy@infradead.org>
Cc: Christoph Hellwig <hch@lst.de>, Ming Lei <ming.lei@redhat.com>,
Jens Axboe <axboe@kernel.dk>,
linux-block@vger.kernel.org,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Dave Chinner <dchinner@redhat.com>,
Linux FS Devel <linux-fsdevel@vger.kernel.org>,
"Darrick J . Wong" <darrick.wong@oracle.com>,
xfs@vger.kernel.org, Bart Van Assche <bvanassche@acm.org>
Subject: Re: [PATCH 0/5] block: introduce helpers for allocating io buffer from slab
Date: Thu, 18 Oct 2018 17:21:33 +0200 [thread overview]
Message-ID: <20181018152133.GA28300@lst.de> (raw)
In-Reply-To: <20181018150605.GC32429@bombadil.infradead.org>
On Thu, Oct 18, 2018 at 08:06:05AM -0700, Matthew Wilcox wrote:
> Can you name one that does require 512-byte alignment, preferably still
> in use? Or even >4-byte alignment. I just checked AHCI and that requires
> only 2-byte alignment.
Xen-blkfront, rsxx, various SD/MMC card readers for example.
> I have reason to believe that these are uncommon because of the feedback
> we got in the NVMe committee after releasing 1.0 which required 4-byte
> alignment from people whining that they just couldn't guarantee 4-byte
> alignment in their host devices and they absolutely needed to have no
> alignment requirements (!)
See how things turned - after NVMe SGLs followed the no alignment
rule enough controller vendors rebelled so that NVMe 1.3 has an option
of SGL support only if 4-byte aligned.
next prev parent reply other threads:[~2018-10-18 15:21 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-18 13:18 [PATCH 0/5] block: introduce helpers for allocating io buffer from slab Ming Lei
2018-10-18 13:18 ` [PATCH 1/5] block: warn on un-aligned DMA IO buffer Ming Lei
2018-10-18 14:27 ` Jens Axboe
2018-10-18 14:43 ` Christoph Hellwig
2018-10-18 14:46 ` Jens Axboe
2018-10-19 1:28 ` Ming Lei
2018-10-19 1:33 ` Jens Axboe
2018-10-19 1:39 ` Ming Lei
2018-10-19 1:52 ` Jens Axboe
2018-10-19 2:06 ` Ming Lei
2018-10-19 2:10 ` Jens Axboe
2018-10-18 14:28 ` Christoph Hellwig
2018-10-18 13:18 ` [PATCH 2/5] block: move .dma_alignment into q->limits Ming Lei
2018-10-18 14:29 ` Christoph Hellwig
2018-10-18 20:36 ` Bart Van Assche
2018-10-18 13:18 ` [PATCH 3/5] block: make dma_alignment as stacked limit Ming Lei
2018-10-18 14:31 ` Christoph Hellwig
2018-10-18 13:18 ` [PATCH 4/5] block: introduce helpers for allocating IO buffers from slab Ming Lei
2018-10-18 14:42 ` Christoph Hellwig
2018-10-18 15:11 ` Matthew Wilcox
2018-10-18 15:22 ` Christoph Hellwig
2018-10-19 2:53 ` Ming Lei
2018-10-19 4:06 ` Jens Axboe
2018-10-19 5:43 ` Dave Chinner
2018-10-18 13:18 ` [PATCH 5/5] xfs: use block layer helpers to allocate io buffer " Ming Lei
2018-10-18 14:03 ` [PATCH 0/5] block: introduce helpers for allocating " Matthew Wilcox
2018-10-18 14:05 ` Christoph Hellwig
2018-10-18 15:06 ` Matthew Wilcox
2018-10-18 15:21 ` Christoph Hellwig [this message]
2018-10-18 15:50 ` Bart Van Assche
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20181018152133.GA28300@lst.de \
--to=hch@lst.de \
--cc=axboe@kernel.dk \
--cc=bvanassche@acm.org \
--cc=darrick.wong@oracle.com \
--cc=dchinner@redhat.com \
--cc=linux-block@vger.kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=ming.lei@redhat.com \
--cc=vkuznets@redhat.com \
--cc=willy@infradead.org \
--cc=xfs@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.