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Re: [Xen-devel] [RFC PATCH 00/13] Persistent grant maps for xen net drivers


        About rx zerocopy, I have a question:

        If some application make a socket, then listen and accept, the client 
sends packets to it, but it doesn't recv from this socket right now, all 
persistent grant page would be in used.
So other application cannot receive any packets.  Is my guess right or wrong?


-----Original Message-----
From: xen-devel-bounces@xxxxxxxxxxxxx [mailto:xen-devel-bounces@xxxxxxxxxxxxx] 
On Behalf Of Joao Martins
Sent: Friday, May 22, 2015 6:27 PM
To: Wei Liu
Cc: ian.campbell@xxxxxxxxxx; netdev@xxxxxxxxxxxxxxx; david.vrabel@xxxxxxxxxx; 
xen-devel@xxxxxxxxxxxxxxxxxxxx; boris.ostrovsky@xxxxxxxxxx
Subject: Re: [Xen-devel] [RFC PATCH 00/13] Persistent grant maps for xen net 

On 19 May 2015, at 17:39, Wei Liu <wei.liu2@xxxxxxxxxx> wrote:

> On Tue, May 12, 2015 at 07:18:24PM +0200, Joao Martins wrote:
>> There have been recently[3] some discussions and issues raised on 
>> persistent grants for the block layer, though the numbers above show 
>> some significant improvements specially on more network intensive 
>> workloads and provide a margin for comparison against future 
>> map/unmap improvements.
>> Any comments or suggestions are welcome, Thanks!
> Thanks, the numbers certainly look interesting.
> I'm just a bit concerned about the complexity of netback. I've 
> commented on individual patches, we can discuss the issues there.

Thanks a lot for the review! It does add more complexity, mainly for the TX 
path, but I also would like to mention that a portion of this changeset is also 
the persistent grants ops that could potentially live outside.


>> [1] http://article.gmane.org/gmane.linux.network/249383
>> [2] http://bit.ly/1IhJfXD
>> [3] 
>> http://lists.xen.org/archives/html/xen-devel/2015-02/msg02292.html
>> Joao Martins (13):
>>  xen-netback: add persistent grant tree ops
>>  xen-netback: xenbus feature persistent support
>>  xen-netback: implement TX persistent grants
>>  xen-netback: implement RX persistent grants
>>  xen-netback: refactor xenvif_rx_action
>>  xen-netback: copy buffer on xenvif_start_xmit()
>>  xen-netback: add persistent tree counters to debugfs
>>  xen-netback: clone skb if skb->xmit_more is set
>>  xen-netfront: move grant_{ref,page} to struct grant
>>  xen-netfront: refactor claim/release grant
>>  xen-netfront: feature-persistent xenbus support
>>  xen-netfront: implement TX persistent grants
>>  xen-netfront: implement RX persistent grants
>> drivers/net/xen-netback/common.h    |  79 ++++
>> drivers/net/xen-netback/interface.c |  78 +++-
>> drivers/net/xen-netback/netback.c   | 873 
>> ++++++++++++++++++++++++++++++------
>> drivers/net/xen-netback/xenbus.c    |  24 +
>> drivers/net/xen-netfront.c          | 362 ++++++++++++---
>> 5 files changed, 1216 insertions(+), 200 deletions(-)
>> --
>> 2.1.3

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