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From: Sowmini Varadhan <sowmini.varadhan@oracle•com>
To: Willem de Bruijn <willemdebruijn.kernel@gmail•com>
Cc: Eric Dumazet <eric.dumazet@gmail•com>,
	Network Development <netdev@vger•kernel.org>,
	David Miller <davem@davemloft•net>,
	rds-devel@oss•oracle.com, santosh.shilimkar@oracle•com
Subject: Re: [PATCH RFC net-next 1/6] sock: MSG_PEEK support for sk_error_queue
Date: Thu, 18 Jan 2018 18:03:41 -0500	[thread overview]
Message-ID: <20180118230341.GG24553@oracle.com> (raw)
In-Reply-To: <CAF=yD-Lnq6yumBn5OcpfmDoCruox=vJFyoh-N0RFrXam2HMn9g@mail.gmail.com>

On (01/18/18 17:54), Willem de Bruijn wrote:
> > 2. If we have the option of passing completion-notification up as ancillary
> >    data on the pollin/recvmsg channel itself (instead of MSG_ERRQUEUE)
> 
> This assumes a somewhat symmetric workload, where there are enough recv
> calls to reap the notification associated with the send calls.

Your comment about the assumption is true, but at least for the database
use-cases, we have a request-response model, so the assumption works out..
I dont know if many other workloads that send large buffers have this
pattern.

> I would stay with MSG_ERRQUEUE processing. One option is to pass data
> up to userspace in the data portion of the notification skb instead of
> encoding it in ancillary data, like tcp_get_timestamping_opt_stats.

that's similar to what I have, except that it does not have the
MSG_PEEK part (you'd need to enforce that the data portion
is upper-bounded, and that the application has the responsibility
of sending down "enough" buffer with recvmsg). 

Note that any one of these choices are ok with me- I have no
special attachments to any of them.

--Sowmini

  reply	other threads:[~2018-01-18 23:03 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-17 12:19 [PATCH RFC net-next 0/6] rds: zerocopy support Sowmini Varadhan
2018-01-17 12:19 ` [PATCH RFC net-next 1/6] sock: MSG_PEEK support for sk_error_queue Sowmini Varadhan
2018-01-17 23:50   ` Willem de Bruijn
2018-01-18 11:02     ` Sowmini Varadhan
2018-01-18 15:54       ` Eric Dumazet
2018-01-18 16:10         ` Sowmini Varadhan
2018-01-18 16:53           ` Eric Dumazet
2018-01-18 17:12             ` Sowmini Varadhan
2018-01-18 22:54               ` Willem de Bruijn
2018-01-18 23:03                 ` Sowmini Varadhan [this message]
2018-01-18 23:09                   ` Willem de Bruijn
2018-01-18 23:20                     ` Sowmini Varadhan
2018-01-18 23:24                       ` Willem de Bruijn
2018-01-18 15:51   ` Eric Dumazet
2018-01-17 12:20 ` [PATCH RFC net-next 2/6] skbuff: export mm_[un]account_pinned_pages for other modules Sowmini Varadhan
2018-01-17 12:20 ` [PATCH RFC net-next 3/6] rds: hold a sock ref from rds_message to the rds_sock Sowmini Varadhan
2018-01-17 12:20 ` [PATCH RFC net-next 4/6] sock: permit SO_ZEROCOPY on PF_RDS socket Sowmini Varadhan
2018-01-18  0:03   ` Willem de Bruijn
2018-01-17 12:20 ` [PATCH RFC net-next 5/6] rds: support for zcopy completion notification Sowmini Varadhan
2018-01-18  0:23   ` Willem de Bruijn
2018-01-18 11:40     ` Sowmini Varadhan
2018-01-18 22:46       ` Willem de Bruijn
2018-01-17 12:20 ` [PATCH RFC net-next 6/6] rds: zerocopy Tx support Sowmini Varadhan
2018-01-18  0:32   ` Willem de Bruijn

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