From: "Michael S. Tsirkin" <mst@redhat.com>
To: John Fastabend <john.fastabend@gmail.com>
Cc: jasowang@redhat.com, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH 2/2] ptr_ring_ll: pop/push multiple objects at once
Date: Wed, 16 Nov 2016 07:23:25 +0200 [thread overview]
Message-ID: <20161116072120-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <582BE39B.9050007@gmail.com>
On Tue, Nov 15, 2016 at 08:42:03PM -0800, John Fastabend wrote:
> On 16-11-14 03:06 PM, Michael S. Tsirkin wrote:
> > On Thu, Nov 10, 2016 at 08:44:32PM -0800, John Fastabend wrote:
> >> Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
> >
> > This will naturally reduce the cache line bounce
> > costs, but so will a _many API for ptr-ring,
> > doing lock-add many-unlock.
> >
> > the number of atomics also scales better with the lock:
> > one per push instead of one per queue.
> >
> > Also, when can qdisc use a _many operation?
> >
>
> On dequeue we can pull off many skbs instead of one at a time and
> then either (a) pass them down as an array to the driver (I started
> to write this on top of ixgbe and it seems like a win) or (b) pass
> them one by one down to the driver and set the xmit_more bit correctly.
>
> The pass one by one also seems like a win because we avoid the lock
> per skb.
>
> On enqueue qdisc side its a bit more evasive to start doing this.
>
>
> [...]
I see. So we could wrap __ptr_ring_consume and
implement __skb_array_consume. You can call that
in a loop under a lock. I would limit it to something
small like 16 pointers, to make sure lock contention is
not an issue.
--
MST
prev parent reply other threads:[~2016-11-16 5:23 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-11 4:43 [RFC PATCH 0/2] illustrate cmpxchg ring for tap/tun and qdisc John Fastabend
2016-11-11 4:44 ` [RFC PATCH 1/2] net: use cmpxchg instead of spinlock in ptr rings John Fastabend
2016-11-14 11:09 ` Jesper Dangaard Brouer
2016-11-14 23:01 ` Michael S. Tsirkin
2016-11-16 4:30 ` John Fastabend
2016-11-11 4:44 ` [RFC PATCH 2/2] ptr_ring_ll: pop/push multiple objects at once John Fastabend
2016-11-14 23:06 ` Michael S. Tsirkin
2016-11-16 4:42 ` John Fastabend
2016-11-16 5:23 ` Michael S. Tsirkin [this message]
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