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xprtrdma: Add ro_unmap_sync method for FMR

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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: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Devesh Sharma <devesh.sharma@avagotech.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
This commit is contained in:
Chuck Lever 2015-12-16 17:22:55 -05:00 committed by Anna Schumaker
parent c9918ff56d
commit 7c7a5390dc
1 changed files with 64 additions and 0 deletions
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64
net/sunrpc/xprtrdma/fmr_ops.c
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@ -179,6 +179,69 @@ out_maperr:
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,