Instead of a globally-contended MR free list, cache MRs in each
rpcrdma_req as they are released. This means acquiring and releasing
an MR will be lock-free in the common case, even outside the
transport send lock.
The original idea of per-rpcrdma_req MR free lists was suggested by
Shirley Ma <shirley.ma@xxxxxxxxxx> several years ago. I just now
figured out how to make that idea work with on-demand MR allocation.
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
---
include/trace/events/rpcrdma.h | 38 ++++++++++++++++++++++++++++++++++++--
net/sunrpc/xprtrdma/frwr_ops.c | 9 ++++++---
net/sunrpc/xprtrdma/rpc_rdma.c | 11 ++++++++---
net/sunrpc/xprtrdma/verbs.c | 18 +++++++++++++++---
net/sunrpc/xprtrdma/xprt_rdma.h | 7 ++++---
5 files changed, 69 insertions(+), 14 deletions(-)
diff --git a/include/trace/events/rpcrdma.h b/include/trace/events/rpcrdma.h
index 83c4dfd..a138306 100644
--- a/include/trace/events/rpcrdma.h
+++ b/include/trace/events/rpcrdma.h
@@ -451,16 +451,50 @@
TP_STRUCT__entry(
__field(const void *, r_xprt)
+ __string(addr, rpcrdma_addrstr(r_xprt))
+ __string(port, rpcrdma_portstr(r_xprt))
__field(unsigned int, count)
),
TP_fast_assign(
__entry->r_xprt = r_xprt;
__entry->count = count;
+ __assign_str(addr, rpcrdma_addrstr(r_xprt));
+ __assign_str(port, rpcrdma_portstr(r_xprt));
),
- TP_printk("r_xprt=%p: created %u MRs",
- __entry->r_xprt, __entry->count
+ TP_printk("peer=[%s]:%s r_xprt=%p: created %u MRs",
+ __get_str(addr), __get_str(port), __entry->r_xprt,
+ __entry->count
+ )
+);
+
+TRACE_EVENT(xprtrdma_mr_get,
+ TP_PROTO(
+ const struct rpcrdma_req *req
+ ),
+
+ TP_ARGS(req),
+
+ TP_STRUCT__entry(
+ __field(const void *, req)
+ __field(unsigned int, task_id)
+ __field(unsigned int, client_id)
+ __field(u32, xid)
+ ),
+
+ TP_fast_assign(
+ const struct rpc_rqst *rqst = &req->rl_slot;
+
+ __entry->req = req;
+ __entry->task_id = rqst->rq_task->tk_pid;
+ __entry->client_id = rqst->rq_task->tk_client->cl_clid;
+ __entry->xid = be32_to_cpu(rqst->rq_xid);
+ ),
+
+ TP_printk("task:%u@%u xid=0x%08x req=%p",
+ __entry->task_id, __entry->client_id, __entry->xid,
+ __entry->req
)
);
diff --git a/net/sunrpc/xprtrdma/frwr_ops.c b/net/sunrpc/xprtrdma/frwr_ops.c
index 1f2e3dd..0e740ba 100644
--- a/net/sunrpc/xprtrdma/frwr_ops.c
+++ b/net/sunrpc/xprtrdma/frwr_ops.c
@@ -488,8 +488,8 @@ static void frwr_wc_localinv_wake(struct ib_cq *cq, struct ib_wc *wc)
/* WARNING: Only wr_cqe and status are reliable at this point */
trace_xprtrdma_wc_li_wake(wc, frwr);
- complete(&frwr->fr_linv_done);
__frwr_release_mr(wc, mr);
+ complete(&frwr->fr_linv_done);
}
/**
@@ -587,11 +587,15 @@ static void frwr_wc_localinv_done(struct ib_cq *cq, struct ib_wc *wc)
struct rpcrdma_frwr *frwr =
container_of(cqe, struct rpcrdma_frwr, fr_cqe);
struct rpcrdma_mr *mr = container_of(frwr, struct rpcrdma_mr, frwr);
+ struct rpcrdma_rep *rep = mr->mr_req->rl_reply;
/* WARNING: Only wr_cqe and status are reliable at this point */
trace_xprtrdma_wc_li_done(wc, frwr);
- rpcrdma_complete_rqst(frwr->fr_req->rl_reply);
__frwr_release_mr(wc, mr);
+
+ /* Ensure @rep is generated before __frwr_release_mr */
+ smp_rmb();
+ rpcrdma_complete_rqst(rep);
}
/**
@@ -624,7 +628,6 @@ void frwr_unmap_async(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req)
frwr = &mr->frwr;
frwr->fr_cqe.done = frwr_wc_localinv;
- frwr->fr_req = req;
last = &frwr->fr_invwr;
last->next = NULL;
last->wr_cqe = &frwr->fr_cqe;
diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c
index 34772cb1..ffeb4df 100644
--- a/net/sunrpc/xprtrdma/rpc_rdma.c
+++ b/net/sunrpc/xprtrdma/rpc_rdma.c
@@ -348,9 +348,14 @@ static struct rpcrdma_mr_seg *rpcrdma_mr_prepare(struct rpcrdma_xprt *r_xprt,
int nsegs, bool writing,
struct rpcrdma_mr **mr)
{
- *mr = rpcrdma_mr_get(r_xprt);
- if (!*mr)
- goto out_getmr_err;
+ *mr = rpcrdma_mr_pop(&req->rl_free_mrs);
+ if (!*mr) {
+ *mr = rpcrdma_mr_get(r_xprt);
+ if (!*mr)
+ goto out_getmr_err;
+ trace_xprtrdma_mr_get(req);
+ (*mr)->mr_req = req;
+ }
rpcrdma_mr_push(*mr, &req->rl_registered);
return frwr_map(r_xprt, seg, nsegs, writing, req->rl_slot.rq_xid, *mr);
diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
index 1fcbe92..1940ffc 100644
--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -76,6 +76,7 @@
static void rpcrdma_sendctx_put_locked(struct rpcrdma_sendctx *sc);
static void rpcrdma_mrs_create(struct rpcrdma_xprt *r_xprt);
static void rpcrdma_mrs_destroy(struct rpcrdma_buffer *buf);
+static void rpcrdma_mr_free(struct rpcrdma_mr *mr);
static struct rpcrdma_regbuf *
rpcrdma_regbuf_alloc(size_t size, enum dma_data_direction direction,
gfp_t flags);
@@ -1014,6 +1015,7 @@ struct rpcrdma_req *rpcrdma_req_create(struct rpcrdma_xprt *r_xprt, size_t size,
if (!req->rl_recvbuf)
goto out4;
+ INIT_LIST_HEAD(&req->rl_free_mrs);
INIT_LIST_HEAD(&req->rl_registered);
spin_lock(&buffer->rb_lock);
list_add(&req->rl_all, &buffer->rb_allreqs);
@@ -1122,11 +1124,13 @@ static void rpcrdma_rep_destroy(struct rpcrdma_rep *rep)
* This function assumes that the caller prevents concurrent device
* unload and transport tear-down.
*/
-void
-rpcrdma_req_destroy(struct rpcrdma_req *req)
+void rpcrdma_req_destroy(struct rpcrdma_req *req)
{
list_del(&req->rl_all);
+ while (!list_empty(&req->rl_free_mrs))
+ rpcrdma_mr_free(rpcrdma_mr_pop(&req->rl_free_mrs));
+
rpcrdma_regbuf_free(req->rl_recvbuf);
rpcrdma_regbuf_free(req->rl_sendbuf);
rpcrdma_regbuf_free(req->rl_rdmabuf);
@@ -1220,7 +1224,6 @@ struct rpcrdma_mr *
void rpcrdma_mr_put(struct rpcrdma_mr *mr)
{
struct rpcrdma_xprt *r_xprt = mr->mr_xprt;
- struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
if (mr->mr_dir != DMA_NONE) {
trace_xprtrdma_mr_unmap(mr);
@@ -1229,6 +1232,15 @@ void rpcrdma_mr_put(struct rpcrdma_mr *mr)
mr->mr_dir = DMA_NONE;
}
+ rpcrdma_mr_push(mr, &mr->mr_req->rl_free_mrs);
+}
+
+static void rpcrdma_mr_free(struct rpcrdma_mr *mr)
+{
+ struct rpcrdma_xprt *r_xprt = mr->mr_xprt;
+ struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
+
+ mr->mr_req = NULL;
spin_lock(&buf->rb_mrlock);
rpcrdma_mr_push(mr, &buf->rb_mrs);
spin_unlock(&buf->rb_mrlock);
diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
index 1f76fa34..6c9830a 100644
--- a/net/sunrpc/xprtrdma/xprt_rdma.h
+++ b/net/sunrpc/xprtrdma/xprt_rdma.h
@@ -239,20 +239,20 @@ struct rpcrdma_sendctx {
* An external memory region is any buffer or page that is registered
* on the fly (ie, not pre-registered).
*/
-struct rpcrdma_req;
struct rpcrdma_frwr {
struct ib_mr *fr_mr;
struct ib_cqe fr_cqe;
struct completion fr_linv_done;
- struct rpcrdma_req *fr_req;
union {
struct ib_reg_wr fr_regwr;
struct ib_send_wr fr_invwr;
};
};
+struct rpcrdma_req;
struct rpcrdma_mr {
struct list_head mr_list;
+ struct rpcrdma_req *mr_req;
struct scatterlist *mr_sg;
int mr_nents;
enum dma_data_direction mr_dir;
@@ -330,7 +330,8 @@ struct rpcrdma_req {
struct list_head rl_all;
struct kref rl_kref;
- struct list_head rl_registered; /* registered segments */
+ struct list_head rl_free_mrs;
+ struct list_head rl_registered;
struct rpcrdma_mr_seg rl_segments[RPCRDMA_MAX_SEGS];
};
