[ofw] RE: [PATCH] ib_qp_create_t

[Fab Tillier]

Can the HCA set it to more than requested?  Or is it only allowed to set it to less?

Having the HCA set it to less introduces a different behavior than the rest of the QP creation parameters, where the call fails if the value is too big (max WR, max SGE, etc).  Requiring a call to query in order to find out whether the requested inline data was granted seems a bit cumbersome.

-Fab

From: Reuven Amitai [mailto:reuven at mellanox.co.il]
Sent: Wednesday, March 26, 2008 1:06 AM
To: Fab Tillier; ofw at lists.openfabrics.org
Subject: RE: [PATCH] ib_qp_create_t

Max inline is input from the user to the HCA but the HCA may set it less than the user request (due to HCA limitations).
I don't think there is one optimal value for max_inline in every situation that HW can set if the user want to use inline data.
ib_qp_create_t is only input and the user should query the qp in order to get the real value of max inline.

Reuven.

________________________________
From: Fab Tillier [mailto:ftillier at windows.microsoft.com]
Sent: Wednesday, March 26, 2008 9:32 AM
To: Reuven Amitai; ofw at lists.openfabrics.org
Subject: RE: [PATCH] ib_qp_create_t
Should max inline be an input or an output?  The optimal size of inline data is something the HW knows, not the consumer.  So perhaps it would make sense for the consumer to indicate that they want to use inline data, and then the HCA driver to return the amount of inline data available?

-Fab

From: ofw-bounces at lists.openfabrics.org [mailto:ofw-bounces at lists.openfabrics.org] On Behalf Of Reuven Amitai
Sent: Wednesday, March 26, 2008 12:30 AM
To: ofw at lists.openfabrics.org
Subject: [ofw] [PATCH] ib_qp_create_t

Hi,

The patch add sq_max_inline member to ib_qp_create_t structure in order to enable setting max_inline
(currently, there is no way to guarantee max inline size in qp creation directly)
we'll need to increase all the relevant interfaces' versions in the next release (because ib_qp_create_t is contained in IOCTL structure(s))

Reuven

Index: hw/mthca/user/mlnx_ual_qp.c
===================================================================
--- hw/mthca/user/mlnx_ual_qp.c     (revision 992)
+++ hw/mthca/user/mlnx_ual_qp.c     (working copy)
@@ -120,7 +120,7 @@
      attr.cap.max_recv_wr          = p_create_attr->rq_depth;
      attr.cap.max_send_sge         = p_create_attr->sq_sge;
      attr.cap.max_recv_sge         = p_create_attr->rq_sge;
-     attr.cap.max_inline_data      = 0;              /* absent in IBAL */
+     attr.cap.max_inline_data      = p_create_attr->sq_max_inline;
      attr.qp_type                                          = p_create_attr->qp_type;
      attr.sq_sig_all                                 = p_create_attr->sq_signaled;

Index: inc/iba/ib_types.h
===================================================================
--- inc/iba/ib_types.h  (revision 992)
+++ inc/iba/ib_types.h  (working copy)
@@ -9755,6 +9755,7 @@
 {
      ib_qp_type_t                  qp_type;

+     uint32_t                      sq_max_inline;
      uint32_t                      sq_depth;
      uint32_t                      rq_depth;
      uint32_t                      sq_sge;
@@ -9772,6 +9773,10 @@
 *    type
 *          Specifies the type of queue pair to create.
 *
+*    sq_max_inline
+*          Maximum payload that can be inlined directly in a WQE, eliminating
+*          protection checks and additional DMA operations.
+*
 *    sq_depth
 *          Indicates the requested maximum number of work requests that may be
 *          outstanding on the queue pair's send queue.  This value must be less


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