From: Jason Wang <jasowang@redhat.com>
To: vyasevic@redhat.com, "Michael S. Tsirkin" <mst@redhat.com>
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
Patrick McHardy <kaber@trash.net>
Subject: Re: [PATCH net-next] macvtap/macvlan: use IFF_NO_QUEUE
Date: Wed, 26 Aug 2015 13:45:30 +0800 [thread overview]
Message-ID: <55DD527A.8040806@redhat.com> (raw)
In-Reply-To: <55DC98A3.7010601@redhat.com>
On 08/26/2015 12:32 AM, Vlad Yasevich wrote:
> On 08/25/2015 07:30 AM, Jason Wang wrote:
>>
>> On 08/25/2015 06:17 PM, Michael S. Tsirkin wrote:
>>> On Mon, Aug 24, 2015 at 04:33:12PM +0800, Jason Wang wrote:
>>>>> For macvlan, switch to use IFF_NO_QUEUE instead of tx_queue_len = 0.
>>>>>
>>>>> For macvtap, after commit 6acf54f1cf0a6747bac9fea26f34cfc5a9029523
>>>>> ("macvtap: Add support of packet capture on macvtap
>>>>> device."). Multiqueue macvtap suffers from single qdisc lock
>>>>> contention. This is because macvtap claims a non zero tx_queue_len and
>>>>> it reuses this value as it socket receive queue size.Thanks to
>>>>> IFF_NO_QUEUE, we can remove the lock contention without breaking
>>>>> existing socket receive queue length logic.
>>>>>
>>>>> Cc: Patrick McHardy <kaber@trash.net>
>>>>> Cc: Vladislav Yasevich <vyasevic@redhat.com>
>>>>> Cc: Michael S. Tsirkin <mst@redhat.com>
>>>>> Signed-off-by: Jason Wang <jasowang@redhat.com>
>>> Seems to make sense. Give me a day or two to get over the jet lag
>>> (and get out from under the pile of mail accumulated while I was traveling),
>>> I'll review properly and ack.
>>>
>> A note on this patch: only default qdisc were removed but we don't lose
>> the ability to attach a qdisc to macvtap (though it may cause lock
>> contention on multiqueue case).
>>
> Wouldn't that lock contention be solved if we really had multiple queues
> for multi-queue macvtaps?
>
> -vlad
Yes, but this introduce another layer of txq locks contention? And it
also needs macvlan multiqueue support. We used to do something like this
but switch to NETIF_F_LLTX finally. You may refer:
2c11455321f37da6fe6cc36353149f9ac9183334 macvlan: add multiqueue capability
8ffab51b3dfc54876f145f15b351c41f3f703195 macvlan: lockless tx path
next prev parent reply other threads:[~2015-08-26 5:45 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-24 8:33 [PATCH net-next] macvtap/macvlan: use IFF_NO_QUEUE Jason Wang
2015-08-25 10:17 ` Michael S. Tsirkin
2015-08-25 11:30 ` Jason Wang
2015-08-25 16:32 ` Vlad Yasevich
2015-08-26 5:45 ` Jason Wang [this message]
2015-08-27 10:43 ` Michael S. Tsirkin
2015-08-28 2:42 ` Jason Wang
2015-08-28 12:25 ` Vlad Yasevich
2015-08-31 2:45 ` Jason Wang
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=55DD527A.8040806@redhat.com \
--to=jasowang@redhat.com \
--cc=kaber@trash.net \
--cc=linux-kernel@vger.kernel.org \
--cc=mst@redhat.com \
--cc=netdev@vger.kernel.org \
--cc=vyasevic@redhat.com \
/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).