public inbox for netdev@vger.kernel.org 
 help / color / mirror / Atom feed

From: Robert Vineyard <vineyard@tuffmail•com>
To: Stephen Hemminger <shemminger@vyatta•com>
Cc: "Peter Huang(Peng)" <peter.huangpeng@huawei•com>,
	kvm@vger•kernel.org, mst@redhat•com, netdev@vger•kernel.org,
	virtualization@lists•linux-foundation.org, avi@redhat•com
Subject: Re: [Question]About KVM network zero-copy  feature!
Date: Sat, 11 Aug 2012 17:54:35 -0400	[thread overview]
Message-ID: <5026D49B.10305@tuffmail.com> (raw)
In-Reply-To: <20120811135556.58ddf48d@nehalam.linuxnetplumber.net>

> On Fri, 10 Aug 2012 11:34:32 +0800
> "Peter Huang(Peng)" <peter.huangpeng@huawei•com> wrote:
>
>> I searched from git-log, and found that until now we have vhost TX zero-copy experiment feature, how
>> about RX zero-copy?

On 08/11/2012 04:55 PM, Stephen Hemminger wrote:
> There is no guarantee that packet will ever be read by receiver. This means zero-copy could
> create memory back pressure stalls.

It would be handy if this could be an optional feature, perhaps not 
enabled by default due to the problem with stalls you mentioned. I would 
love to see RX zero-copy implemented natively in KVM, as it might 
alleviate the need for custom solutions like vPF_RING:

http://www.ntop.org/products/pf_ring/vpf_ring/

Every time a packet is copied, especially from kernel space to user 
space, there is an opportunity for it to be dropped on its way to the 
receiving application - which is unacceptable when monitoring high-speed 
networks for security or bandwidth accounting purposes.

I am attempting to find a highly-efficient way to deploy virtualized 
network monitoring sensors (Snort, for example). Ideally I want to 
exploit symmetric hardware-based RSS and SR-IOV functionality for 
load-balancing and packet distribution completely in ASIC. I've found 
other existing work in this area (also using custom drivers) indicating 
significant performance gains in the non-virtualized case:

http://www.ndsl.kaist.edu/~shinae/papers/TR-symRSS.pdf

Is there any interest in exploring native RX zero-copy within the 
mainline KVM networking code?

Thanks,
Robert Vineyard

next prev parent reply	other threads:[~2012-08-11 21:54 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-08-10  3:34 [Question]About KVM network zero-copy feature! Peter Huang(Peng)
2012-08-11 20:55 ` Stephen Hemminger
2012-08-11 21:54   ` Robert Vineyard [this message]
2012-08-12  0:42     ` Robert Vineyard
2012-08-12  9:37       ` Michael S. Tsirkin
2012-08-13  1:24         ` Peter Huang(Peng)
2012-08-13  7:18           ` Michael S. Tsirkin
2012-08-13  3:45         ` Robert Vineyard
2012-08-13  5:59           ` Robert Vineyard

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=5026D49B.10305@tuffmail.com \
    --to=vineyard@tuffmail$(echo .)com \
    --cc=avi@redhat$(echo .)com \
    --cc=kvm@vger$(echo .)kernel.org \
    --cc=mst@redhat$(echo .)com \
    --cc=netdev@vger$(echo .)kernel.org \
    --cc=peter.huangpeng@huawei$(echo .)com \
    --cc=shemminger@vyatta$(echo .)com \
    --cc=virtualization@lists$(echo .)linux-foundation.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox