From: Stefan Hajnoczi <[email protected]>
To: Konrad Rzeszutek Wilk <[email protected]>
Cc: Jens Axboe <[email protected]>, Sargun Dhillon <[email protected]>,
Kees Cook <[email protected]>,
[email protected], [email protected],
Kernel Hardening <[email protected]>,
Jann Horn <[email protected]>, Aleksa Sarai <[email protected]>,
Christian Brauner <[email protected]>,
[email protected],
Alexander Viro <[email protected]>,
Jeff Moyer <[email protected]>,
Stefano Garzarella <[email protected]>
Subject: Re: [PATCH RFC 0/3] io_uring: add restrictions to support untrusted applications and guests
Date: Mon, 13 Jul 2020 10:24:35 +0100 [thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <20200710162017.qdu34ermtxh3rfgl@steredhat>
[-- Attachment #1: Type: text/plain, Size: 1557 bytes --]
On Fri, Jul 10, 2020 at 06:20:17PM +0200, Stefano Garzarella wrote:
> On Fri, Jul 10, 2020 at 11:33:09AM -0400, Konrad Rzeszutek Wilk wrote:
> > .snip..
> > > Just to recap the proposal, the idea is to add some restrictions to the
> > > operations (sqe, register, fixed file) to safely allow untrusted applications
> > > or guests to use io_uring queues.
> >
> > Hi!
> >
> > This is neat and quite cool - but one thing that keeps nagging me is
> > what how much overhead does this cut from the existing setup when you use
> > virtio (with guests obviously)?
>
> I need to do more tests, but the preliminary results that I reported on
> the original proposal [1] show an overhead of ~ 4.17 uS (with iodepth=1)
> when I'm using virtio ring processed in a dedicated iothread:
>
> - 73 kIOPS using virtio-blk + QEMU iothread + io_uring backend
> - 104 kIOPS using io_uring passthrough
>
> > That is from a high level view the
> > beaty of io_uring being passed in the guest is you don't have the
> > virtio ring -> io_uring processing, right?
>
> Right, and potentially we can share the io_uring queues directly to the
> guest userspace applications, cutting down the cost of Linux block
> layer in the guest.
Another factor is that the guest submits requests directly to the host
kernel sqpoll thread. When a virtqueue is used the sqpoll thread cannot
poll it directly so another host thread (QEMU) needs to poll the
virtqueue. The same applies for the completion code path.
Stefan
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]
prev parent reply other threads:[~2020-07-13 9:24 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-10 14:19 [PATCH RFC 0/3] io_uring: add restrictions to support untrusted applications and guests Stefano Garzarella
2020-07-10 14:19 ` [PATCH RFC 1/3] io_uring: use an enumeration for io_uring_register(2) opcodes Stefano Garzarella
2020-07-10 14:19 ` [PATCH RFC 2/3] io_uring: add IOURING_REGISTER_RESTRICTIONS opcode Stefano Garzarella
2020-07-10 17:52 ` Jens Axboe
2020-07-13 8:07 ` Stefano Garzarella
2020-07-10 14:19 ` [PATCH RFC 3/3] io_uring: allow disabling rings during the creation Stefano Garzarella
2020-07-10 15:33 ` [PATCH RFC 0/3] io_uring: add restrictions to support untrusted applications and guests Konrad Rzeszutek Wilk
2020-07-10 16:20 ` Stefano Garzarella
2020-07-13 9:24 ` Stefan Hajnoczi [this message]
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 \
[email protected] \
[email protected] \
[email protected] \
[email protected] \
[email protected] \
[email protected] \
[email protected] \
[email protected] \
[email protected] \
[email protected] \
[email protected] \
[email protected] \
[email protected] \
[email protected] \
[email protected] \
[email protected] \
/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