netdev - Re: [PATCH v3 net-next 4/7] rds: support for zcopy completion notification

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Date:   Thu, 15 Feb 2018 11:46:55 -0800
From:   Santosh Shilimkar <santosh.shilimkar@...cle.com>
To:     Sowmini Varadhan <sowmini.varadhan@...cle.com>,
        netdev@...r.kernel.org, willemdebruijn.kernel@...il.com
Cc:     davem@...emloft.net, rds-devel@....oracle.com
Subject: Re: [PATCH v3 net-next 4/7] rds: support for zcopy completion
 notification

On 2/15/2018 10:49 AM, Sowmini Varadhan wrote:
> RDS removes a datagram (rds_message) from the retransmit queue when
> an ACK is received. The ACK indicates that the receiver has queued
> the RDS datagram, so that the sender can safely forget the datagram.
> When all references to the rds_message are quiesced, rds_message_purge
> is called to release resources used by the rds_message
> 
> If the datagram to be removed had pinned pages set up, add
> an entry to the rs->rs_znotify_queue so that the notifcation
> will be sent up via rds_rm_zerocopy_callback() when the
> rds_message is eventually freed by rds_message_purge.
> 
> rds_rm_zerocopy_callback() attempts to batch the number of cookies
> sent with each notification  to a max of SO_EE_ORIGIN_MAX_ZCOOKIES.
> This is achieved by checking the tail skb in the sk_error_queue:
> if this has room for one more cookie, the cookie from the
> current notification is added; else a new skb is added to the
> sk_error_queue. Every invocation of rds_rm_zerocopy_callback() will
> trigger a ->sk_error_report to notify the application.
> 
> Signed-off-by: Sowmini Varadhan <sowmini.varadhan@...cle.com>
> ---
Acked-by: Santosh Shilimkar <santosh.shilimkar@...cle.com>