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  1. 29 Oct, 2008 1 commit
  3. 28 Oct, 2008 1 commit
  5. 14 Oct, 2008 1 commit
  7. 09 Jul, 2008 1 commit
    • Chuck Lever's avatar
      SUNRPC: Ensure all transports set rq_xtime consistently · b22602a6
      Chuck Lever authored 
      
The RPC client uses the rq_xtime field in each RPC request to determine the
round-trip time of the request.  Currently, the rq_xtime field is
initialized by each transport just before it starts enqueing a request to
be sent.  However, transports do not handle initializing this value
consistently; sometimes they don't initialize it at all.

To make the measurement of request round-trip time consistent for all
RPC client transport capabilities, pull rq_xtime initialization into the
RPC client's generic transport logic.  Now all transports will get a
standardized RTT measure automatically, from:

  xprt_transmit()

to

  xprt_complete_rqst()

This makes round-trip time calculation more accurate for the TCP transport.
The socket ->sendmsg() method can return "-EAGAIN" if the socket's output
buffer is full, so the TCP transport's ->send_request() method may call
the ->sendmsg() method repeatedly until it gets all of the request's bytes
queued in the socket's buffer.

Currently, the TCP transport sets the rq_xtime field every time through
that loop so the final value is the timestamp just before the *last* call
to the underlying socket's ->sendmsg() method.  After this patch, the
rq_xtime field contains a timestamp that reflects the time just before the
*first* call to ->sendmsg().

This is consequential under heavy workloads because large requests often
take multiple ->sendmsg() calls to get all the bytes of a request queued.
The TCP transport causes the request to sleep until the remote end of the
socket has received enough bytes to clear space in the socket's local
output buffer.  This delay can be quite significant.

The method introduced by this patch is a more accurate measure of RTT
for stream transports, since the server can cause enough back pressure
to delay (ie increase the latency of) requests from the client.

Additionally, this patch corrects the behavior of the RDMA transport, which
entirely neglected to initialize the rq_xtime field.  RPC performance
metrics for RDMA transports now display correct RPC request round trip
times.
Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
Acked-by: default avatarTom Talpey <thomas.talpey@netapp.com>
Signed-off-by: default avatarTrond Myklebust <Trond.Myklebust@netapp.com>
      b22602a6
  9. 19 Apr, 2008 3 commits
    • Trond Myklebust's avatar
      SUNRPC: Don't disconnect more than once if retransmitting NFSv4 requests · 7c1d71cf
      Trond Myklebust authored 
      
NFSv4 requires us to ensure that we break the TCP connection before we're
allowed to retransmit a request. However in the case where we're
retransmitting several requests that have been sent on the same
connection, we need to ensure that we don't interfere with the attempt to
reconnect and/or break the connection again once it has been established.

We therefore introduce a 'connection' cookie that is bumped every time a
connection is broken. This allows requests to track if they need to force a
disconnection.
Signed-off-by: default avatarTrond Myklebust <Trond.Myklebust@netapp.com>
      7c1d71cf
    • Trond Myklebust's avatar
      SUNRPC: remove XS_SENDMSG_RETRY · 06b4b681
      Trond Myklebust authored 
      
The condition for exiting from the loop in xs_tcp_send_request() should be
that we find we're not making progress (i.e. number of bytes sent is 0).
Signed-off-by: default avatarTrond Myklebust <Trond.Myklebust@netapp.com>
      06b4b681
    • Trond Myklebust's avatar
      SUNRPC: Fix up xprt_write_space() · b6ddf64f
      Trond Myklebust authored 
      
The rest of the networking layer uses SOCK_ASYNC_NOSPACE to signal whether
or not we have someone waiting for buffer memory. Convert the SUNRPC layer
to use the same idiom.
Remove the unlikely()s in xs_udp_write_space and xs_tcp_write_space. In
fact, the most common case will be that there is nobody waiting for buffer
space.

SOCK_NOSPACE is there to tell the TCP layer whether or not the cwnd was
limited by the application window. Ensure that we follow the same idiom as
the rest of the networking layer here too.

Finally, ensure that we clear SOCK_ASYNC_NOSPACE once we wake up, so that
write_space() doesn't keep waking things up on xprt->pending.
Signed-off-by: default avatarTrond Myklebust <Trond.Myklebust@netapp.com>
      b6ddf64f
  11. 06 Mar, 2008 1 commit
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  25. 09 Oct, 2007 14 commits