xprtrdma: Acquire FMRs in rpcrdma_fmr_register_external()
Acquiring 64 FMRs in rpcrdma_buffer_get() while holding the buffer
pool lock is expensive, and unnecessary because FMR mode can
transfer up to a 1MB payload using just a single ib_fmr.
Instead, acquire ib_fmrs one-at-a-time as chunks are registered, and
return them to rb_mws immediately during deregistration.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Steve Wise <swise@opengridcomputing.com>
Tested-By: Devesh Sharma <devesh.sharma@avagotech.com>
Reviewed-by: Doug Ledford <dledford@redhat.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
diff --git a/net/sunrpc/xprtrdma/fmr_ops.c b/net/sunrpc/xprtrdma/fmr_ops.c
index 0a96155..53fb649 100644
--- a/net/sunrpc/xprtrdma/fmr_ops.c
+++ b/net/sunrpc/xprtrdma/fmr_ops.c
@@ -11,6 +11,21 @@
* can take tens of usecs to complete.
*/
+/* Normal operation
+ *
+ * A Memory Region is prepared for RDMA READ or WRITE using the
+ * ib_map_phys_fmr verb (fmr_op_map). When the RDMA operation is
+ * finished, the Memory Region is unmapped using the ib_unmap_fmr
+ * verb (fmr_op_unmap).
+ */
+
+/* Transport recovery
+ *
+ * After a transport reconnect, fmr_op_map re-uses the MR already
+ * allocated for the RPC, but generates a fresh rkey then maps the
+ * MR again. This process is synchronous.
+ */
+
#include "xprt_rdma.h"
#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
@@ -77,6 +92,15 @@
return rc;
}
+static int
+__fmr_unmap(struct rpcrdma_mw *r)
+{
+ LIST_HEAD(l);
+
+ list_add(&r->r.fmr->list, &l);
+ return ib_unmap_fmr(&l);
+}
+
/* Use the ib_map_phys_fmr() verb to register a memory region
* for remote access via RDMA READ or RDMA WRITE.
*/
@@ -88,9 +112,22 @@
struct ib_device *device = ia->ri_device;
enum dma_data_direction direction = rpcrdma_data_dir(writing);
struct rpcrdma_mr_seg *seg1 = seg;
- struct rpcrdma_mw *mw = seg1->rl_mw;
u64 physaddrs[RPCRDMA_MAX_DATA_SEGS];
int len, pageoff, i, rc;
+ struct rpcrdma_mw *mw;
+
+ mw = seg1->rl_mw;
+ seg1->rl_mw = NULL;
+ if (!mw) {
+ mw = rpcrdma_get_mw(r_xprt);
+ if (!mw)
+ return -ENOMEM;
+ } else {
+ /* this is a retransmit; generate a fresh rkey */
+ rc = __fmr_unmap(mw);
+ if (rc)
+ return rc;
+ }
pageoff = offset_in_page(seg1->mr_offset);
seg1->mr_offset -= pageoff; /* start of page */
@@ -114,6 +151,7 @@
if (rc)
goto out_maperr;
+ seg1->rl_mw = mw;
seg1->mr_rkey = mw->r.fmr->rkey;
seg1->mr_base = seg1->mr_dma + pageoff;
seg1->mr_nsegs = i;
@@ -137,18 +175,24 @@
{
struct rpcrdma_ia *ia = &r_xprt->rx_ia;
struct rpcrdma_mr_seg *seg1 = seg;
+ struct rpcrdma_mw *mw = seg1->rl_mw;
int rc, nsegs = seg->mr_nsegs;
- LIST_HEAD(l);
- list_add(&seg1->rl_mw->r.fmr->list, &l);
- rc = ib_unmap_fmr(&l);
+ dprintk("RPC: %s: FMR %p\n", __func__, mw);
+
+ seg1->rl_mw = NULL;
while (seg1->mr_nsegs--)
rpcrdma_unmap_one(ia->ri_device, seg++);
+ rc = __fmr_unmap(mw);
if (rc)
goto out_err;
+ rpcrdma_put_mw(r_xprt, mw);
return nsegs;
out_err:
+ /* The FMR is abandoned, but remains in rb_all. fmr_op_destroy
+ * will attempt to release it when the transport is destroyed.
+ */
dprintk("RPC: %s: ib_unmap_fmr status %i\n", __func__, rc);
return nsegs;
}