From: Paolo Bonzini <pbonzini@redhat.com>
To: Nicholas Thomas <nick@bytemark.co.uk>
Cc: kwolf@redhat.com, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH 12/12] nbd: split requests
Date: Fri, 09 Sep 2011 17:33:57 +0200 [thread overview]
Message-ID: <4E6A31E5.3070208@redhat.com> (raw)
In-Reply-To: <4E6A2823.9080103@bytemark.co.uk>
On 09/09/2011 04:52 PM, Nicholas Thomas wrote:
>> > +/* qemu-nbd has a limit of slightly less than 1M per request. For safety,
>> > + * transfer at most 512K per request. */
>> > +#define NBD_MAX_SECTORS 1024
>
> As far as I'm aware, the limit of 1MiB - header size is common to all
> NBD servers. I'm not aware of anything at all that'll fail on a 768K
> request but succeed in the exact same circumstances on a 512K request.
> Again, this is a performance consideration - each request is relatively
> slow, so you don't want them to be unnecessarily small.
Yes, it should probably be bumped to 1536 or 2040 (to keep requests
4k-aligned). I wasn't sure about the limit. I've never seen requests
that big anyway.
Paolo
next prev parent reply other threads:[~2011-09-09 15:34 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-08 15:24 [Qemu-devel] [PATCH 00/12] nbd improvements Paolo Bonzini
2011-09-08 15:24 ` [Qemu-devel] [PATCH 01/12] nbd: support feature negotiation Paolo Bonzini
2011-09-08 15:24 ` [Qemu-devel] [PATCH 02/12] nbd: sync API definitions with upstream Paolo Bonzini
2011-09-12 14:15 ` Kevin Wolf
2011-09-12 15:08 ` Paolo Bonzini
2011-09-08 15:24 ` [Qemu-devel] [PATCH 03/12] nbd: support NBD_SET_FLAGS ioctl Paolo Bonzini
2011-09-08 15:24 ` [Qemu-devel] [PATCH 04/12] nbd: add support for NBD_CMD_FLUSH Paolo Bonzini
2011-09-13 13:52 ` Kevin Wolf
2011-09-13 15:13 ` Paolo Bonzini
2011-09-08 15:24 ` [Qemu-devel] [PATCH 05/12] nbd: add support for NBD_CMD_FLAG_FUA Paolo Bonzini
2011-09-13 13:55 ` Kevin Wolf
2011-09-08 15:24 ` [Qemu-devel] [PATCH 06/12] nbd: support NBD_CMD_TRIM in the server Paolo Bonzini
2011-09-13 13:58 ` Kevin Wolf
2011-09-13 15:14 ` Paolo Bonzini
2011-09-14 15:44 ` Christoph Hellwig
2011-09-14 16:25 ` Paolo Bonzini
2011-09-08 15:25 ` [Qemu-devel] [PATCH 07/12] sheepdog: add coroutine_fn markers Paolo Bonzini
2011-09-08 15:25 ` [Qemu-devel] [PATCH 08/12] add socket_set_block Paolo Bonzini
2011-09-08 15:25 ` [Qemu-devel] [PATCH 09/12] sheepdog: move coroutine send/recv function to generic code Paolo Bonzini
2011-09-09 4:53 ` MORITA Kazutaka
2011-09-09 8:11 ` [Qemu-devel] [PATCH v2 " Paolo Bonzini
2011-09-13 0:28 ` MORITA Kazutaka
2011-09-13 14:14 ` Kevin Wolf
2011-09-13 15:16 ` Paolo Bonzini
2011-09-13 15:36 ` Kevin Wolf
2011-09-13 15:38 ` Paolo Bonzini
2011-09-08 15:25 ` [Qemu-devel] [PATCH 10/12] block: add bdrv_co_flush support Paolo Bonzini
2011-09-08 15:25 ` [Qemu-devel] [PATCH 11/12] nbd: switch to asynchronous operation Paolo Bonzini
2011-09-09 14:52 ` Nicholas Thomas
2011-09-09 15:03 ` Paolo Bonzini
2011-09-09 15:34 ` Paolo Bonzini
2011-09-08 15:25 ` [Qemu-devel] [PATCH 12/12] nbd: split requests Paolo Bonzini
2011-09-09 14:52 ` Nicholas Thomas
2011-09-09 15:33 ` Paolo Bonzini [this message]
2011-09-09 9:00 ` [Qemu-devel] [PATCH 00/12] nbd improvements Kevin Wolf
2011-09-09 10:29 ` Paolo Bonzini
2011-09-09 10:42 ` Kevin Wolf
2011-09-09 10:50 ` Nicholas Thomas
2011-09-09 11:00 ` Paolo Bonzini
2011-09-09 11:04 ` Kevin Wolf
2011-09-09 14:51 ` Nicholas Thomas
2011-09-14 9:50 ` Kevin Wolf
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=4E6A31E5.3070208@redhat.com \
--to=pbonzini@redhat.com \
--cc=kwolf@redhat.com \
--cc=nick@bytemark.co.uk \
--cc=qemu-devel@nongnu.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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).