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ib_srpt: Add max_sge_delta kernel module parameter

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git-svn-id: http://svn.code.sf.net/p/scst/svn/trunk@5795 d57e44dd-8a1f-0410-8b47-8ef2f437770f
This commit is contained in:
Bart Van Assche
2014-09-10 12:18:09 +00:00
parent 7fd9a3af66
commit f4f568f884
2 changed files with 14 additions and 13 deletions
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srpt/README
+9
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@@ -38,6 +38,15 @@ Building and installing the SRP target driver is possible as follows:
fi
The ib_srpt kernel module supports the following parameters:
* max_sge_delta (unsigned): Number to subtract from max_sge. Some but not
all HCA's allow to use up to max_sge S/G-list elements in RDMA
communication. The default value of this parameter is 3 and works with all
HCA's. If you know that the HCA's that are used by the ib_srpt driver allow
to use S/G-lists that are longer than max_sge - 3 then you can decrease this
parameter. Note: setting this parameter too low will cause SRP every login
to fail and will cause a message similar to the following to be logged on
the target system: "ib_srpt: RDMA t ... for idx ... failed with status 12".
* one_target_per_port (boolean) and
* use_node_guid_in_target_name (boolean)
ib_srpt can operate in one of the following three modes:
srpt/src/ib_srpt.c
+5 -13
View File
@@ -171,6 +171,10 @@ MODULE_PARM_DESC(srpt_service_guid,
"Using this value for ioc_guid, id_ext, and cm_listen_id"
" instead of using the node_guid of the first HCA.");
static unsigned max_sge_delta = 3;
module_param(max_sge_delta, uint, 0444);
MODULE_PARM_DESC(max_sge_delta, "Number to subtract from max_sge.");
/*
* Note: changing any of the two constants below into SCST_CONTEXT_DIRECT is
* dangerous because it might cause IB completions to be processed too late
@@ -2151,19 +2155,7 @@ static int srpt_create_ch_ib(struct srpt_rdma_ch *ch)
qp_init->sq_sig_type = IB_SIGNAL_REQ_WR;
qp_init->qp_type = IB_QPT_RC;
qp_init->cap.max_send_wr = srpt_sq_size;
/*
* A quote from the OFED 1.5.3.1 release notes
* (docs/release_notes/mthca_release_notes.txt), section "Known Issues":
* In mem-free devices, RC QPs can be created with a maximum of
* (max_sge - 1) entries only; UD QPs can be created with a maximum of
* (max_sge - 3) entries.
* A quote from the OFED 1.2.5 release notes
* (docs/mthca_release_notes.txt), section "Known Issues":
* In mem-free devices, RC QPs can be created with a maximum of
* (max_sge - 3) entries only.
*/
ch->max_sge = sdev->dev_attr.max_sge - 3;
WARN_ON(ch->max_sge < 1);
ch->max_sge = max_t(int, 1, sdev->dev_attr.max_sge - max_sge_delta);
qp_init->cap.max_send_sge = ch->max_sge;
if (ch->using_rdma_cm) {