netdev - Re: [Lsf] [Lsf-pc] [LSF/MM TOPIC] Generic page-pool recycle facility?

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Message-ID: <20160411203738.58a6adb2@redhat.com>
Date:	Mon, 11 Apr 2016 20:37:38 +0200
From:	Jesper Dangaard Brouer <brouer@...hat.com>
To:	Thadeu Lima de Souza Cascardo <cascardo@...hat.com>
Cc:	Matthew Wilcox <willy@...ux.intel.com>,
	Mel Gorman <mgorman@...hsingularity.net>,
	James Bottomley <James.Bottomley@...senPartnership.com>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	Brenden Blanco <bblanco@...mgrid.com>,
	lsf@...ts.linux-foundation.org, linux-mm <linux-mm@...ck.org>,
	Mel Gorman <mgorman@...e.de>,
	Tom Herbert <tom@...bertland.com>,
	lsf-pc@...ts.linux-foundation.org,
	Alexei Starovoitov <alexei.starovoitov@...il.com>,
	brouer@...hat.com
Subject: Re: [Lsf] [Lsf-pc] [LSF/MM TOPIC] Generic page-pool recycle
 facility?

On Mon, 11 Apr 2016 14:46:25 -0300
Thadeu Lima de Souza Cascardo <cascardo@...hat.com> wrote:

> So, Jesper, please take into consideration that this pool design
> would rather be per device. Otherwise, we allow some device to write
> into another's device/driver memory.

Yes, that was my intended use.  I want to have a page-pool per device.
I actually, want to go as far as a page-pool per NIC HW RX-ring queue.

Because the other use-case for the page-pool is zero-copy RX.

The NIC HW trick is that we today can create a HW filter in the NIC
(via ethtool) and place that traffic into a separate RX queue in the
NIC.  Lets say matching NFS traffic or guest traffic. Then we can allow
RX zero-copy of these pages, into the application/guest, somehow
binding it to RX queue, e.g. introducing a "cross-domain-id" in the
page-pool page that need to match.

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  Author of http://www.iptv-analyzer.org
  LinkedIn: http://www.linkedin.com/in/brouer