From 8d38de65644d900199f035277aa5f3da4aa9fc17 Mon Sep 17 00:00:00 2001 From: Chuck Lever Date: Tue, 29 Nov 2016 10:52:16 -0500 Subject: [PATCH] xprtrdma: Make FRWR send queue entry accounting more accurate Verbs providers may perform house-keeping on the Send Queue during each signaled send completion. It is necessary therefore for a verbs consumer (like xprtrdma) to occasionally force a signaled send completion if it runs unsignaled most of the time. xprtrdma does not require signaled completions for Send or FastReg Work Requests, but does signal some LocalInv Work Requests. To ensure that Send Queue house-keeping can run before the Send Queue is more than half-consumed, xprtrdma forces a signaled completion on occasion by counting the number of Send Queue Entries it consumes. It currently does this by counting each ib_post_send as one Entry. Commit c9918ff56dfb ("xprtrdma: Add ro_unmap_sync method for FRWR") introduced the ability for frwr_op_unmap_sync to post more than one Work Request with a single post_send. Thus the underlying assumption of one Send Queue Entry per ib_post_send is no longer true. Also, FastReg Work Requests are currently never signaled. They should be signaled once in a while, just as Send is, to keep the accounting of consumed SQEs accurate. While we're here, convert the CQCOUNT macros to the currently preferred kernel coding style, which is inline functions. Fixes: c9918ff56dfb ("xprtrdma: Add ro_unmap_sync method for FRWR") Signed-off-by: Chuck Lever Signed-off-by: Anna Schumaker --- net/sunrpc/xprtrdma/frwr_ops.c | 13 ++++++++++--- net/sunrpc/xprtrdma/verbs.c | 10 ++-------- net/sunrpc/xprtrdma/xprt_rdma.h | 20 ++++++++++++++++++-- 3 files changed, 30 insertions(+), 13 deletions(-) diff --git a/net/sunrpc/xprtrdma/frwr_ops.c b/net/sunrpc/xprtrdma/frwr_ops.c index 26b26beef2d4..adbf52c6df83 100644 --- a/net/sunrpc/xprtrdma/frwr_ops.c +++ b/net/sunrpc/xprtrdma/frwr_ops.c @@ -421,7 +421,7 @@ frwr_op_map(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg, IB_ACCESS_REMOTE_WRITE | IB_ACCESS_LOCAL_WRITE : IB_ACCESS_REMOTE_READ; - DECR_CQCOUNT(&r_xprt->rx_ep); + rpcrdma_set_signaled(&r_xprt->rx_ep, ®_wr->wr); rc = ib_post_send(ia->ri_id->qp, ®_wr->wr, &bad_wr); if (rc) goto out_senderr; @@ -486,7 +486,7 @@ frwr_op_unmap_sync(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req) struct rpcrdma_ia *ia = &r_xprt->rx_ia; struct rpcrdma_mw *mw, *tmp; struct rpcrdma_frmr *f; - int rc; + int count, rc; dprintk("RPC: %s: req %p\n", __func__, req); @@ -496,6 +496,7 @@ frwr_op_unmap_sync(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req) * a single ib_post_send() call. */ f = NULL; + count = 0; invalidate_wrs = pos = prev = NULL; list_for_each_entry(mw, &req->rl_registered, mw_list) { if ((rep->rr_wc_flags & IB_WC_WITH_INVALIDATE) && @@ -505,6 +506,7 @@ frwr_op_unmap_sync(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req) } pos = __frwr_prepare_linv_wr(mw); + count++; if (!invalidate_wrs) invalidate_wrs = pos; @@ -523,7 +525,12 @@ frwr_op_unmap_sync(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req) f->fr_invwr.send_flags = IB_SEND_SIGNALED; f->fr_cqe.done = frwr_wc_localinv_wake; reinit_completion(&f->fr_linv_done); - INIT_CQCOUNT(&r_xprt->rx_ep); + + /* Initialize CQ count, since there is always a signaled + * WR being posted here. The new cqcount depends on how + * many SQEs are about to be consumed. + */ + rpcrdma_init_cqcount(&r_xprt->rx_ep, count); /* Transport disconnect drains the receive CQ before it * replaces the QP. The RPC reply handler won't call us diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c index ec74289af7ec..451f5f27d8af 100644 --- a/net/sunrpc/xprtrdma/verbs.c +++ b/net/sunrpc/xprtrdma/verbs.c @@ -532,7 +532,7 @@ rpcrdma_ep_create(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia, ep->rep_cqinit = ep->rep_attr.cap.max_send_wr/2 - 1; if (ep->rep_cqinit <= 2) ep->rep_cqinit = 0; /* always signal? */ - INIT_CQCOUNT(ep); + rpcrdma_init_cqcount(ep, 0); init_waitqueue_head(&ep->rep_connect_wait); INIT_DELAYED_WORK(&ep->rep_connect_worker, rpcrdma_connect_worker); @@ -1311,13 +1311,7 @@ rpcrdma_ep_post(struct rpcrdma_ia *ia, dprintk("RPC: %s: posting %d s/g entries\n", __func__, send_wr->num_sge); - if (DECR_CQCOUNT(ep) > 0) - send_wr->send_flags = 0; - else { /* Provider must take a send completion every now and then */ - INIT_CQCOUNT(ep); - send_wr->send_flags = IB_SEND_SIGNALED; - } - + rpcrdma_set_signaled(ep, send_wr); rc = ib_post_send(ia->ri_id->qp, send_wr, &send_wr_fail); if (rc) goto out_postsend_err; diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h index 6e1bba358203..f6ae1b22da47 100644 --- a/net/sunrpc/xprtrdma/xprt_rdma.h +++ b/net/sunrpc/xprtrdma/xprt_rdma.h @@ -95,8 +95,24 @@ struct rpcrdma_ep { struct delayed_work rep_connect_worker; }; -#define INIT_CQCOUNT(ep) atomic_set(&(ep)->rep_cqcount, (ep)->rep_cqinit) -#define DECR_CQCOUNT(ep) atomic_sub_return(1, &(ep)->rep_cqcount) +static inline void +rpcrdma_init_cqcount(struct rpcrdma_ep *ep, int count) +{ + atomic_set(&ep->rep_cqcount, ep->rep_cqinit - count); +} + +/* To update send queue accounting, provider must take a + * send completion every now and then. + */ +static inline void +rpcrdma_set_signaled(struct rpcrdma_ep *ep, struct ib_send_wr *send_wr) +{ + send_wr->send_flags = 0; + if (unlikely(atomic_sub_return(1, &ep->rep_cqcount) <= 0)) { + rpcrdma_init_cqcount(ep, 0); + send_wr->send_flags = IB_SEND_SIGNALED; + } +} /* Pre-allocate extra Work Requests for handling backward receives * and sends. This is a fixed value because the Work Queues are -- 2.20.1