linux-kernel - Re: [PATCH v5 0/2] skb_array: array based FIFO for skbs

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Message-ID: <574CF703.9030200@redhat.com>
Date:	Tue, 31 May 2016 10:29:23 +0800
From:	Jason Wang <jasowang@...hat.com>
To:	"Michael S. Tsirkin" <mst@...hat.com>
Cc:	linux-kernel@...r.kernel.org,
	Eric Dumazet <eric.dumazet@...il.com>, davem@...emloft.net,
	netdev@...r.kernel.org, Steven Rostedt <rostedt@...dmis.org>,
	brouer@...hat.com
Subject: Re: [PATCH v5 0/2] skb_array: array based FIFO for skbs



On 2016年05月30日 23:37, Michael S. Tsirkin wrote:
> On Mon, May 30, 2016 at 05:59:33PM +0800, Jason Wang wrote:
>>
>> On 2016年05月23日 18:43, Michael S. Tsirkin wrote:
>>> This is in response to the proposal by Jason to make tun
>>> rx packet queue lockless using a circular buffer.
>>> My testing seems to show that at least for the common usecase
>>> in networking, which isn't lockless, circular buffer
>>> with indices does not perform that well, because
>>> each index access causes a cache line to bounce between
>>> CPUs, and index access causes stalls due to the dependency.
>> I change tun to use skb array, looks like it can give about 5% more faster
>> than skb ring.
> OK and skb ring is 9% faster than the linked list, so together
> this is a 14% speedup?

Right.

>
>> And we usually don't need touch bhs during consume and produce (e.g for the
>> case of tun).
>>
>> Thanks
> Maybe I'll drop it in v6 then ...
> Could you post the full tun patchset please?
>

Since it needs no bh versions of produce/consume, maybe you can post v6 
first, then I can post the tun patches?