[rds-devel] [PATCH RFC net-next 1/6] sock: MSG_PEEK support for sk_error_queue
Sowmini Varadhan
sowmini.varadhan at oracle.com
Thu Jan 18 15:03:41 PST 2018
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
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