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xprtrdma: Acquire MRs in rpcrdma_register_external()

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Acquiring 64 MRs in rpcrdma_buffer_get() while holding the buffer
pool lock is expensive, and unnecessary because most modern adapters
can transfer 100s of KBs of payload using just a single MR.

Instead, acquire MRs one-at-a-time as chunks are registered, and
return them to rb_mws immediately during deregistration.

Note: commit 539431a437 ("xprtrdma: Don't invalidate FRMRs if
registration fails") is reverted: There is now a valid case where
registration can fail (with -ENOMEM) but the QP is still in RTS.

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 11:52:35 -04:00 committed by Anna Schumaker
parent 951e721ca0
commit c14d86e591
3 changed files with 89 additions and 35 deletions
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100
net/sunrpc/xprtrdma/frwr_ops.c
View File

@ -11,6 +11,62 @@
* but most complex memory registration mode.
*/
/* Normal operation
*
* A Memory Region is prepared for RDMA READ or WRITE using a FAST_REG
* Work Request (frmr_op_map). When the RDMA operation is finished, this
* Memory Region is invalidated using a LOCAL_INV Work Request
* (frmr_op_unmap).
*
* Typically these Work Requests are not signaled, and neither are RDMA
* SEND Work Requests (with the exception of signaling occasionally to
* prevent provider work queue overflows). This greatly reduces HCA
* interrupt workload.
*
* As an optimization, frwr_op_unmap marks MRs INVALID before the
* LOCAL_INV WR is posted. If posting succeeds, the MR is placed on
* rb_mws immediately so that no work (like managing a linked list
* under a spinlock) is needed in the completion upcall.
*
* But this means that frwr_op_map() can occasionally encounter an MR
* that is INVALID but the LOCAL_INV WR has not completed. Work Queue
* ordering prevents a subsequent FAST_REG WR from executing against
* that MR while it is still being invalidated.
*/
/* Transport recovery
*
* ->op_map and the transport connect worker cannot run at the same
* time, but ->op_unmap can fire while the transport connect worker
* is running. Thus MR recovery is handled in ->op_map, to guarantee
* that recovered MRs are owned by a sending RPC, and not one where
* ->op_unmap could fire at the same time transport reconnect is
* being done.
*
* When the underlying transport disconnects, MRs are left in one of
* three states:
*
* INVALID: The MR was not in use before the QP entered ERROR state.
* (Or, the LOCAL_INV WR has not completed or flushed yet).
*
* STALE: The MR was being registered or unregistered when the QP
* entered ERROR state, and the pending WR was flushed.
*
* VALID: The MR was registered before the QP entered ERROR state.
*
* When frwr_op_map encounters STALE and VALID MRs, they are recovered
* with ib_dereg_mr and then are re-initialized. Beause MR recovery
* allocates fresh resources, it is deferred to a workqueue, and the
* recovered MRs are placed back on the rb_mws list when recovery is
* complete. frwr_op_map allocates another MR for the current RPC while
* the broken MR is reset.
*
* To ensure that frwr_op_map doesn't encounter an MR that is marked
* INVALID but that is about to be flushed due to a previous transport
* disconnect, the transport connect worker attempts to drain all
* pending send queue WRs before the transport is reconnected.
*/
#include "xprt_rdma.h"
#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
@ -250,9 +306,9 @@ frwr_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;
struct rpcrdma_frmr *frmr = &mw->r.frmr;
struct ib_mr *mr = frmr->fr_mr;
struct rpcrdma_mw *mw;
struct rpcrdma_frmr *frmr;
struct ib_mr *mr;
struct ib_send_wr fastreg_wr, *bad_wr;
u8 key;
int len, pageoff;
@ -261,12 +317,25 @@ frwr_op_map(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg,
u64 pa;
int page_no;
mw = seg1->rl_mw;
seg1->rl_mw = NULL;
do {
if (mw)
__frwr_queue_recovery(mw);
mw = rpcrdma_get_mw(r_xprt);
if (!mw)
return -ENOMEM;
} while (mw->r.frmr.fr_state != FRMR_IS_INVALID);
frmr = &mw->r.frmr;
frmr->fr_state = FRMR_IS_VALID;
pageoff = offset_in_page(seg1->mr_offset);
seg1->mr_offset -= pageoff; /* start of page */
seg1->mr_len += pageoff;
len = -pageoff;
if (nsegs > ia->ri_max_frmr_depth)
nsegs = ia->ri_max_frmr_depth;
for (page_no = i = 0; i < nsegs;) {
rpcrdma_map_one(device, seg, direction);
pa = seg->mr_dma;
@ -285,8 +354,6 @@ frwr_op_map(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg,
dprintk("RPC: %s: Using frmr %p to map %d segments (%d bytes)\n",
__func__, mw, i, len);
frmr->fr_state = FRMR_IS_VALID;
memset(&fastreg_wr, 0, sizeof(fastreg_wr));
fastreg_wr.wr_id = (unsigned long)(void *)mw;
fastreg_wr.opcode = IB_WR_FAST_REG_MR;
@ -298,6 +365,7 @@ frwr_op_map(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg,
fastreg_wr.wr.fast_reg.access_flags = writing ?
IB_ACCESS_REMOTE_WRITE | IB_ACCESS_LOCAL_WRITE :
IB_ACCESS_REMOTE_READ;
mr = frmr->fr_mr;
key = (u8)(mr->rkey & 0x000000FF);
ib_update_fast_reg_key(mr, ++key);
fastreg_wr.wr.fast_reg.rkey = mr->rkey;
@ -307,6 +375,7 @@ frwr_op_map(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg,
if (rc)
goto out_senderr;
seg1->rl_mw = mw;
seg1->mr_rkey = mr->rkey;
seg1->mr_base = seg1->mr_dma + pageoff;
seg1->mr_nsegs = i;
@ -315,10 +384,9 @@ frwr_op_map(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg,
out_senderr:
dprintk("RPC: %s: ib_post_send status %i\n", __func__, rc);
ib_update_fast_reg_key(mr, --key);
frmr->fr_state = FRMR_IS_INVALID;
while (i--)
rpcrdma_unmap_one(device, --seg);
__frwr_queue_recovery(mw);
return rc;
}
@ -330,15 +398,19 @@ frwr_op_unmap(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg)
{
struct rpcrdma_mr_seg *seg1 = seg;
struct rpcrdma_ia *ia = &r_xprt->rx_ia;
struct rpcrdma_mw *mw = seg1->rl_mw;
struct ib_send_wr invalidate_wr, *bad_wr;
int rc, nsegs = seg->mr_nsegs;
seg1->rl_mw->r.frmr.fr_state = FRMR_IS_INVALID;
dprintk("RPC: %s: FRMR %p\n", __func__, mw);
seg1->rl_mw = NULL;
mw->r.frmr.fr_state = FRMR_IS_INVALID;
memset(&invalidate_wr, 0, sizeof(invalidate_wr));
invalidate_wr.wr_id = (unsigned long)(void *)seg1->rl_mw;
invalidate_wr.wr_id = (unsigned long)(void *)mw;
invalidate_wr.opcode = IB_WR_LOCAL_INV;
invalidate_wr.ex.invalidate_rkey = seg1->rl_mw->r.frmr.fr_mr->rkey;
invalidate_wr.ex.invalidate_rkey = mw->r.frmr.fr_mr->rkey;
DECR_CQCOUNT(&r_xprt->rx_ep);
while (seg1->mr_nsegs--)
@ -348,12 +420,13 @@ frwr_op_unmap(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg)
read_unlock(&ia->ri_qplock);
if (rc)
goto out_err;
rpcrdma_put_mw(r_xprt, mw);
return nsegs;
out_err:
/* Force rpcrdma_buffer_get() to retry */
seg1->rl_mw->r.frmr.fr_state = FRMR_IS_STALE;
dprintk("RPC: %s: ib_post_send status %i\n", __func__, rc);
__frwr_queue_recovery(mw);
return nsegs;
}
@ -400,6 +473,9 @@ frwr_op_destroy(struct rpcrdma_buffer *buf)
{
struct rpcrdma_mw *r;
/* Ensure stale MWs for "buf" are no longer in flight */
flush_workqueue(frwr_recovery_wq);
while (!list_empty(&buf->rb_all)) {
r = list_entry(buf->rb_all.next, struct rpcrdma_mw, mw_all);
list_del(&r->mw_all);

3
net/sunrpc/xprtrdma/rpc_rdma.c
View File

@ -284,9 +284,6 @@ rpcrdma_create_chunks(struct rpc_rqst *rqst, struct xdr_buf *target,
return (unsigned char *)iptr - (unsigned char *)headerp;
out:
if (r_xprt->rx_ia.ri_memreg_strategy == RPCRDMA_FRMR)
return n;
for (pos = 0; nchunks--;)
pos += r_xprt->rx_ia.ri_ops->ro_unmap(r_xprt,
&req->rl_segments[pos]);

21
net/sunrpc/xprtrdma/verbs.c
View File

@ -1336,12 +1336,11 @@ rpcrdma_buffer_get_frmrs(struct rpcrdma_req *req, struct rpcrdma_buffer *buf,
struct rpcrdma_req *
rpcrdma_buffer_get(struct rpcrdma_buffer *buffers)
{
struct rpcrdma_ia *ia = rdmab_to_ia(buffers);
struct list_head stale;
struct rpcrdma_req *req;
unsigned long flags;
spin_lock_irqsave(&buffers->rb_lock, flags);
if (buffers->rb_send_index == buffers->rb_max_requests) {
spin_unlock_irqrestore(&buffers->rb_lock, flags);
dprintk("RPC: %s: out of request buffers\n", __func__);
@ -1360,17 +1359,7 @@ rpcrdma_buffer_get(struct rpcrdma_buffer *buffers)
}
buffers->rb_send_bufs[buffers->rb_send_index++] = NULL;
INIT_LIST_HEAD(&stale);
switch (ia->ri_memreg_strategy) {
case RPCRDMA_FRMR:
req = rpcrdma_buffer_get_frmrs(req, buffers, &stale);
break;
default:
break;
}
spin_unlock_irqrestore(&buffers->rb_lock, flags);
if (!list_empty(&stale))
rpcrdma_retry_flushed_linv(&stale, buffers);
return req;
}
@ -1382,18 +1371,10 @@ void
rpcrdma_buffer_put(struct rpcrdma_req *req)
{
struct rpcrdma_buffer *buffers = req->rl_buffer;
struct rpcrdma_ia *ia = rdmab_to_ia(buffers);
unsigned long flags;
spin_lock_irqsave(&buffers->rb_lock, flags);
rpcrdma_buffer_put_sendbuf(req, buffers);
switch (ia->ri_memreg_strategy) {
case RPCRDMA_FRMR:
rpcrdma_buffer_put_mrs(req, buffers);
break;
default:
break;
}
spin_unlock_irqrestore(&buffers->rb_lock, flags);
}