• Chuck Lever's avatar
    xprtrdma: Use xprt_pin_rqst in rpcrdma_reply_handler · 9590d083
    Chuck Lever authored
    Adopt the use of xprt_pin_rqst to eliminate contention between
    Call-side users of rb_lock and the use of rb_lock in
    rpcrdma_reply_handler.
    
    This replaces the mechanism introduced in 431af645 ("xprtrdma:
    Fix client lock-up after application signal fires").
    
    Use recv_lock to quickly find the completing rqst, pin it, then
    drop the lock. At that point invalidation and pull-up of the Reply
    XDR can be done. Both are often expensive operations.
    
    Finally, take recv_lock again to signal completion to the RPC
    layer. It also protects adjustment of "cwnd".
    
    This greatly reduces the amount of time a lock is held by the
    reply handler. Comparing lock_stat results shows a marked decrease
    in contention on rb_lock and recv_lock.
    Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
    [trond.myklebust@primarydata.com: Remove call to rpcrdma_buffer_put() from
       the "out_norqst:" path in rpcrdma_reply_handler.]
    Signed-off-by: default avatarTrond Myklebust <trond.myklebust@primarydata.com>
    9590d083
xprt_rdma.h 19.6 KB