Re: [PATCH v1 08/13] xprtrdma: Back off rkey when FAST_REG_MR fails

Chuck Lever
2014-06-24T16:26:32Z

On Jun 24, 2014, at 11:47 AM, Anna Schumaker <schumaker.anna-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:

> On 06/23/2014 06:40 PM, Chuck Lever wrote:
>> If posting a FAST_REG_MR Work Reqeust fails, or the FAST_REG WR
>> flushes, revert the rkey update to avoid subsequent
>> IB_WC_MW_BIND_ERR completions.
>>
>> Suggested-by: Steve Wise <swise-7bPotxP6k4+P2YhJcF5u+vpXobYPEAuW@public.gmane.org>
>> Signed-off-by: Chuck Lever <chuck.lever-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
>> ---
>> net/sunrpc/xprtrdma/verbs.c | 39 +++++++++++++++++++++++++++++----------
>> 1 file changed, 29 insertions(+), 10 deletions(-)
>>
>> diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
>> index cef67fd..3efc007 100644
>> --- a/net/sunrpc/xprtrdma/verbs.c
>> +++ b/net/sunrpc/xprtrdma/verbs.c
>> @@ -61,6 +61,8 @@
>> # define RPCDBG_FACILITY RPCDBG_TRANS
>> #endif
>>
>> +static void rpcrdma_decrement_frmr_rkey(struct rpcrdma_mw *);
>> +
>> /*
>> * internal functions
>> */
>> @@ -154,13 +156,17 @@ rpcrdma_sendcq_process_wc(struct ib_wc *wc)
>>
>> if (wrid == 0)
>> return;
>> - if (wc->status != IB_WC_SUCCESS)
>> - return;
>>
>> fastreg = test_and_clear_bit(RPCRDMA_BIT_FASTREG, &wrid);
>> mw = (struct rpcrdma_mw *)wrid;
>>
>> - mw->r.frmr.fr_state = fastreg ? FRMR_IS_VALID : FRMR_IS_INVALID;
>> + if (wc->status == IB_WC_SUCCESS) {
>> + mw->r.frmr.fr_state = fastreg ?
>> + FRMR_IS_VALID : FRMR_IS_INVALID;
>> + } else {
>> + if (fastreg)
>> + rpcrdma_decrement_frmr_rkey(mw);
>
> Isn't this the same as "else if (fastreg)”?

Yep, those are logically equivalent. I left them separate, and
left the extra braces, so it would be cleaner to add more logic in
both arms of “if (wc->status == IB_WC_SUCCESS)” in subsequent
patches.

Using “switch (wc->status)” might be more future-proof.

> Anna
>
>> + }
>> }
>>
>> static int
>> @@ -1480,6 +1486,24 @@ rpcrdma_unmap_one(struct rpcrdma_ia *ia, struct rpcrdma_mr_seg *seg)
>> seg->mr_dma, seg->mr_dmalen, seg->mr_dir);
>> }
>>
>> +static void
>> +rpcrdma_increment_frmr_rkey(struct rpcrdma_mw *mw)
>> +{
>> + struct ib_mr *frmr = mw->r.frmr.fr_mr;
>> + u8 key = frmr->rkey & 0x000000FF;
>> +
>> + ib_update_fast_reg_key(frmr, ++key);
>> +}
>> +
>> +static void
>> +rpcrdma_decrement_frmr_rkey(struct rpcrdma_mw *mw)
>> +{
>> + struct ib_mr *frmr = mw->r.frmr.fr_mr;
>> + u8 key = frmr->rkey & 0x000000FF;
>> +
>> + ib_update_fast_reg_key(frmr, --key);
>> +}
>> +
>> static int
>> rpcrdma_register_frmr_external(struct rpcrdma_mr_seg *seg,
>> int *nsegs, int writing, struct rpcrdma_ia *ia,
>> @@ -1487,8 +1511,6 @@ rpcrdma_register_frmr_external(struct rpcrdma_mr_seg *seg,
>> {
>> struct rpcrdma_mr_seg *seg1 = seg;
>> struct ib_send_wr invalidate_wr, frmr_wr, *bad_wr, *post_wr;
>> -
>> - u8 key;
>> int len, pageoff;
>> int i, rc;
>> int seg_len;
>> @@ -1552,14 +1574,10 @@ rpcrdma_register_frmr_external(struct rpcrdma_mr_seg *seg,
>> rc = -EIO;
>> goto out_err;
>> }
>> -
>> - /* Bump the key */
>> - key = (u8)(seg1->mr_chunk.rl_mw->r.frmr.fr_mr->rkey & 0x000000FF);
>> - ib_update_fast_reg_key(seg1->mr_chunk.rl_mw->r.frmr.fr_mr, ++key);
>> -
>> frmr_wr.wr.fast_reg.access_flags = (writing ?
>> IB_ACCESS_REMOTE_WRITE | IB_ACCESS_LOCAL_WRITE :
>> IB_ACCESS_REMOTE_READ);
>> + rpcrdma_increment_frmr_rkey(seg1->mr_chunk.rl_mw);
>> frmr_wr.wr.fast_reg.rkey = seg1->mr_chunk.rl_mw->r.frmr.fr_mr->rkey;
>> DECR_CQCOUNT(&r_xprt->rx_ep);
>>
>> @@ -1568,6 +1586,7 @@ rpcrdma_register_frmr_external(struct rpcrdma_mr_seg *seg,
>> if (rc) {
>> dprintk("RPC: %s: failed ib_post_send for register,"
>> " status %i\n", __func__, rc);
>> + rpcrdma_decrement_frmr_rkey(seg1->mr_chunk.rl_mw);
>> goto out_err;
>> } else {
>> seg1->mr_rkey = seg1->mr_chunk.rl_mw->r.frmr.fr_mr->rkey;
>>
>> --
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>

--
Chuck Lever
chuck[dot]lever[at]oracle[dot]com

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