Re: [PATCH net-next] RDS: deliver zerocopy completion notification with data as an optimization

On (02/21/18 19:39), Willem de Bruijn wrote: > >> By the way, the put_cmsg is unconditional even if the caller did > >> not supply msg_control. So it is basically no longer safe to ever > >> call read, recv or recvfrom on a socket if zerocopy notifications > >> are outstanding. > > > > Wait, I

Re: [PATCH net-next] RDS: deliver zerocopy completion notification with data as an optimization

On Wed, Feb 21, 2018 at 7:26 PM, Sowmini Varadhan wrote: > On (02/21/18 18:45), Willem de Bruijn wrote: >> >> I do mean returning 0 instead of -EAGAIN if control data is ready. >> Something like >> >> @@ -611,7 +611,8 @@ int rds_recvmsg(struct socket *sock, struct

Re: [PATCH net-next] RDS: deliver zerocopy completion notification with data as an optimization

On (02/21/18 18:45), Willem de Bruijn wrote: > > I do mean returning 0 instead of -EAGAIN if control data is ready. > Something like > > @@ -611,7 +611,8 @@ int rds_recvmsg(struct socket *sock, struct msghdr > *msg, size_t size, > > if (!rds_next_incoming(rs, )) { >

Re: [PATCH net-next] RDS: deliver zerocopy completion notification with data as an optimization

>> Okay. If callers must already handle 0 as a valid return code, then >> it is fine to add another case that does this. >> >> The extra branch in the hot path is still rather unfortunately. Could >> this be integrated in the existing if (nonblock) branch below? > > that's where I first started.

Re: [PATCH net-next] RDS: deliver zerocopy completion notification with data as an optimization

On (02/21/18 17:50), Willem de Bruijn wrote: > > In the common case no more than one notification will be outstanding, > but with a fixed number of notifications per packet, in edge cases this > list may be long. : > Socket functions block if sk_err is non-zero. See for instance >

Re: [PATCH net-next] RDS: deliver zerocopy completion notification with data as an optimization

On Wed, Feb 21, 2018 at 5:14 PM, Sowmini Varadhan wrote: > On (02/21/18 16:54), Willem de Bruijn wrote: >> >> I'd put this optimization behind a socket option. > > Yes, that thought occurred to me as well- I think RDS applications > are unlikely to use the error_queue

Re: [PATCH net-next] RDS: deliver zerocopy completion notification with data as an optimization

On (02/21/18 16:54), Willem de Bruijn wrote: > > I'd put this optimization behind a socket option. Yes, that thought occurred to me as well- I think RDS applications are unlikely to use the error_queue path because, as I mentioned before, these are heavily request-response based, so you're

Re: [PATCH net-next] RDS: deliver zerocopy completion notification with data as an optimization

On Wed, Feb 21, 2018 at 3:19 PM, Sowmini Varadhan wrote: > This commit is an optimization that builds on top of commit 01883eda72bd > ("rds: support for zcopy completion notification") for PF_RDS sockets. > > Cookies associated with zerocopy completion are passed up

Re: [PATCH net-next] RDS: deliver zerocopy completion notification with data as an optimization

On 2/21/2018 12:19 PM, Sowmini Varadhan wrote: This commit is an optimization that builds on top of commit 01883eda72bd ("rds: support for zcopy completion notification") for PF_RDS sockets. Cookies associated with zerocopy completion are passed up on the POLLIN channel, piggybacked with data

[PATCH net-next] RDS: deliver zerocopy completion notification with data as an optimization

This commit is an optimization that builds on top of commit 01883eda72bd ("rds: support for zcopy completion notification") for PF_RDS sockets. Cookies associated with zerocopy completion are passed up on the POLLIN channel, piggybacked with data whereever possible. Such cookies are passed up as