netdev - Re: [PATCH v3 net-next 5/7] rds: zerocopy Tx support.

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Message-ID: <ba7e66cd-d0fe-fbf8-d03f-6fa778c47dd4@oracle.com>
Date:   Thu, 15 Feb 2018 11:47:56 -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 5/7] rds: zerocopy Tx support.

On 2/15/2018 10:49 AM, Sowmini Varadhan wrote:
> If the MSG_ZEROCOPY flag is specified with rds_sendmsg(), and,
> if the SO_ZEROCOPY socket option has been set on the PF_RDS socket,
> application pages sent down with rds_sendmsg() are pinned.
> 
> The pinning uses the accounting infrastructure added by
> Commit a91dbff551a6 ("sock: ulimit on MSG_ZEROCOPY pages")
> 
> The payload bytes in the message may not be modified for the
> duration that the message has been pinned. A multi-threaded
> application using this infrastructure may thus need to be notified
> about send-completion so that it can free/reuse the buffers
> passed to rds_sendmsg(). Notification of send-completion will
> identify each message-buffer by a cookie that the application
> must specify as ancillary data to rds_sendmsg().
> The ancillary data in this case has cmsg_level == SOL_RDS
> and cmsg_type == RDS_CMSG_ZCOPY_COOKIE.
> 
> Signed-off-by: Sowmini Varadhan <sowmini.varadhan@...cle.com>
> ---

Acked-by: Santosh Shilimkar <santosh.shilimkar@...cle.com>