At 01:26 PM 10/8/2008, Trond Myklebust wrote:
>On Wed, 2008-10-08 at 11:47 -0400, Tom Talpey wrote:
>> From: Tom Tucker <talpey@xxxxxxxxxx>
>
>Now I'm really confused!
Ok, that's a bug. :-)
Will fix, after figuring out the format you prefer for joint authors.
Tom.
>
>> This logic sets the connection parameter that configures the local device
>> and informs the remote peer how many concurrent incoming RDMA_READ
>> requests are supported. The original logic didn't really do what was
>> intended for two reasons:
>>
>> - The max number supported by the device is typically smaller than
>> any one factor in the calculation used, and
>>
>> - The field in the connection parameter structure where the value is
>> stored is a u8 and always overflows for the default settings.
>>
>> So what really happens is the value requested for responder resources
>> is the left over 8 bits from the "desired value". If the desired value
>> happened to be a multiple of 256, the result was zero and it wouldn't
>> connect at all.
>>
>> Given the above and the fact that max_requests is almost always larger
>> than the max responder resources supported by the adapter, this patch
>> simplifies this logic and simply requests the max supported by the device,
>> subject to a reasonable limit.
>>
>> This bug was found by Jim Schutt at Sandia.
>>
>> Signed-off-by: Tom Tucker <tom@xxxxxxxxxxxxxxxxxxxxx>
>> Signed-off-by: Tom Talpey <talpey@xxxxxxxxxx>
>> ---
>>
>> net/sunrpc/xprtrdma/verbs.c | 51
>++++++++++++-------------------------------
>> 1 files changed, 14 insertions(+), 37 deletions(-)
>>
>> diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
>> index 39a1652..e3fe905 100644
>> --- a/net/sunrpc/xprtrdma/verbs.c
>> +++ b/net/sunrpc/xprtrdma/verbs.c
>> @@ -705,30 +705,13 @@ rpcrdma_ep_create(struct rpcrdma_ep *ep,
>struct rpcrdma_ia *ia,
>> ep->rep_remote_cma.private_data_len = 0;
>>
>> /* Client offers RDMA Read but does not initiate */
>> - switch (ia->ri_memreg_strategy) {
>> - case RPCRDMA_BOUNCEBUFFERS:
>> + ep->rep_remote_cma.initiator_depth = 0;
>> + if (ia->ri_memreg_strategy == RPCRDMA_BOUNCEBUFFERS)
>> ep->rep_remote_cma.responder_resources = 0;
>> - break;
>> - case RPCRDMA_MTHCAFMR:
>> - case RPCRDMA_REGISTER:
>> - case RPCRDMA_FRMR:
>> - ep->rep_remote_cma.responder_resources = cdata->max_requests *
>> - (RPCRDMA_MAX_DATA_SEGS / 8);
>> - break;
>> - case RPCRDMA_MEMWINDOWS:
>> - case RPCRDMA_MEMWINDOWS_ASYNC:
>> -#if RPCRDMA_PERSISTENT_REGISTRATION
>> - case RPCRDMA_ALLPHYSICAL:
>> -#endif
>> - ep->rep_remote_cma.responder_resources = cdata->max_requests *
>> - (RPCRDMA_MAX_DATA_SEGS / 2);
>> - break;
>> - default:
>> - break;
>> - }
>> - if (ep->rep_remote_cma.responder_resources > devattr.max_qp_rd_atom)
>> + else if (devattr.max_qp_rd_atom > 32) /* arbitrary but <= 255 */
>> + ep->rep_remote_cma.responder_resources = 32;
>> + else
>> ep->rep_remote_cma.responder_resources = devattr.max_qp_rd_atom;
>> - ep->rep_remote_cma.initiator_depth = 0;
>>
>> ep->rep_remote_cma.retry_count = 7;
>> ep->rep_remote_cma.flow_control = 0;
>> @@ -858,14 +841,6 @@ if
>(strnicmp(ia->ri_id->device->dma_device->bus->name, "pci", 3) == 0) {
>> }
>> }
>>
>> - /* Theoretically a client initiator_depth > 0 is not needed,
>> - * but many peers fail to complete the connection unless they
>> - * == responder_resources! */
>> - if (ep->rep_remote_cma.initiator_depth !=
>> - ep->rep_remote_cma.responder_resources)
>> - ep->rep_remote_cma.initiator_depth =
>> - ep->rep_remote_cma.responder_resources;
>> -
>> ep->rep_connected = 0;
>>
>> rc = rdma_connect(ia->ri_id, &ep->rep_remote_cma);
>> @@ -894,14 +869,16 @@ if
>(strnicmp(ia->ri_id->device->dma_device->bus->name, "pci", 3) == 0) {
>> if (ep->rep_connected <= 0) {
>> /* Sometimes, the only way to reliably connect to remote
>> * CMs is to use same nonzero values for ORD and IRD. */
>> - ep->rep_remote_cma.initiator_depth =
>> - ep->rep_remote_cma.responder_resources;
>> - if (ep->rep_remote_cma.initiator_depth == 0)
>> - ++ep->rep_remote_cma.initiator_depth;
>> - if (ep->rep_remote_cma.responder_resources == 0)
>> - ++ep->rep_remote_cma.responder_resources;
>> - if (retry_count++ == 0)
>> + if (retry_count++ <= RDMA_CONNECT_RETRY_MAX + 1 &&
>> + (ep->rep_remote_cma.responder_resources == 0 ||
>> + ep->rep_remote_cma.initiator_depth !=
>> + ep->rep_remote_cma.responder_resources)) {
>> + if (ep->rep_remote_cma.responder_resources == 0)
>> + ep->rep_remote_cma.responder_resources = 1;
>> + ep->rep_remote_cma.initiator_depth =
>> + ep->rep_remote_cma.responder_resources;
>> goto retry;
>> + }
>> rc = ep->rep_connected;
>> } else {
>> dprintk("RPC: %s: connected\n", __func__);
>>
>> --
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