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Commit 7c7a5390 authored by Chuck Lever's avatar Chuck Lever Committed by Anna Schumaker
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xprtrdma: Add ro_unmap_sync method for FMR 



FMR's ro_unmap method is already synchronous because ib_unmap_fmr()
is a synchronous verb. However, some improvements can be made here.

1. Gather all the MRs for the RPC request onto a list, and invoke
   ib_unmap_fmr() once with that list. This reduces the number of
   doorbells when there is more than one MR to invalidate

2. Perform the DMA unmap _after_ the MRs are unmapped, not before.
   This is critical after invalidating a Write chunk.

Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
Tested-by: default avatarDevesh Sharma <devesh.sharma@avagotech.com>
Signed-off-by: default avatarAnna Schumaker <Anna.Schumaker@Netapp.com>
parent c9918ff5

net/sunrpc/xprtrdma/fmr_ops.c

+64 −0
Original line number Diff line number Diff line
@@ -179,6 +179,69 @@ fmr_op_map(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg, 
	return rc;

}



static void

__fmr_dma_unmap(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg)

{

	struct ib_device *device = r_xprt->rx_ia.ri_device;

	struct rpcrdma_mw *mw = seg->rl_mw;

	int nsegs = seg->mr_nsegs;



	seg->rl_mw = NULL;



	while (nsegs--)

		rpcrdma_unmap_one(device, seg++);



	rpcrdma_put_mw(r_xprt, mw);

}



/* Invalidate all memory regions that were registered for "req".

 *

 * Sleeps until it is safe for the host CPU to access the

 * previously mapped memory regions.

 */

static void

fmr_op_unmap_sync(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req)

{

	struct rpcrdma_mr_seg *seg;

	unsigned int i, nchunks;

	struct rpcrdma_mw *mw;

	LIST_HEAD(unmap_list);

	int rc;



	dprintk("RPC:       %s: req %p\n", __func__, req);



	/* ORDER: Invalidate all of the req's MRs first

	 *

	 * ib_unmap_fmr() is slow, so use a single call instead

	 * of one call per mapped MR.

	 */

	for (i = 0, nchunks = req->rl_nchunks; nchunks; nchunks--) {

		seg = &req->rl_segments[i];

		mw = seg->rl_mw;



		list_add(&mw->r.fmr.fmr->list, &unmap_list);



		i += seg->mr_nsegs;

	}

	rc = ib_unmap_fmr(&unmap_list);

	if (rc)

		pr_warn("%s: ib_unmap_fmr failed (%i)\n", __func__, rc);



	/* ORDER: Now DMA unmap all of the req's MRs, and return

	 * them to the free MW list.

	 */

	for (i = 0, nchunks = req->rl_nchunks; nchunks; nchunks--) {

		seg = &req->rl_segments[i];



		__fmr_dma_unmap(r_xprt, seg);



		i += seg->mr_nsegs;

		seg->mr_nsegs = 0;

	}



	req->rl_nchunks = 0;

}



/* Use the ib_unmap_fmr() verb to prevent further remote

 * access via RDMA READ or RDMA WRITE.

 */
@@ -231,6 +294,7 @@ fmr_op_destroy(struct rpcrdma_buffer *buf) 


const struct rpcrdma_memreg_ops rpcrdma_fmr_memreg_ops = {

	.ro_map				= fmr_op_map,

	.ro_unmap_sync			= fmr_op_unmap_sync,

	.ro_unmap			= fmr_op_unmap,

	.ro_open			= fmr_op_open,

	.ro_maxpages			= fmr_op_maxpages,