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xprtrdma: Acquire FMRs in rpcrdma_fmr_register_external()

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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>
This commit is contained in:
Chuck Lever
2015-05-26 11:52:16 -04:00
committed by Anna Schumaker
parent 346aa66b2a
commit fc7fbb59e7
2 changed files with 48 additions and 30 deletions
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52
net/sunrpc/xprtrdma/fmr_ops.c
View File

@@ -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 @@ out_fmr_err:
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 @@ fmr_op_map(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg,
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 @@ fmr_op_map(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg,
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 @@ fmr_op_unmap(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg)
{
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;
}