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ib_srpt: Limit the number of scatter/gather elements in RDMA READs to max_sge_rd

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Additionally, declare the max_sge_delta parameter obsolete.


git-svn-id: http://svn.code.sf.net/p/scst/svn/trunk@8983 d57e44dd-8a1f-0410-8b47-8ef2f437770f
This commit is contained in:
Bart Van Assche
2020-05-25 18:19:45 +00:00
parent 52497bb8b6
commit ac0de9d485
2 changed files with 2 additions and 52 deletions
Download Patch File Download Diff File Expand all files Collapse all files
srpt/README
-8
View File
@@ -39,14 +39,6 @@ Building and installing the SRP target driver is possible as follows:
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".
* rdma_cm_port (number)
A 16-bit number that specifies the port number to be registered via the
RDMA/CM. Must be specified to make communication over RoCE or iWARP
srpt/src/ib_srpt.c
+2 -44
View File
@@ -166,7 +166,7 @@ MODULE_PARM_DESC(srpt_service_guid,
static unsigned int max_sge_delta = 0;
module_param(max_sge_delta, uint, 0444);
MODULE_PARM_DESC(max_sge_delta, "Number to subtract from max_sge.");
MODULE_PARM_DESC(max_sge_delta, "Number to subtract from max_sge (obsolete).");
/*
* Note: changing any of the two constants below into SCST_CONTEXT_DIRECT is
@@ -2340,49 +2340,6 @@ retry:
#else
ch->max_send_sge = sdev->dev_attr.max_sge;
#endif
if (max_sge_delta == 0) {
#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 3, 0)
/*
* See also commit b9560a419bfd ("RDMA: Move driver_id into
* struct ib_device_ops") # v5.3.
*/
switch (sdev->device->ops.driver_id) {
case RDMA_DRIVER_MLX4:
/*
* The smallest max_sge_delta value that works with
* ConnectX-3 firmware version 2.42.5000.
*/
max_sge_delta = 2;
break;
case RDMA_DRIVER_MTHCA:
/*
* From the OFED release notes: In mem-free devices, RC
* QPs can be created with a maximum of (max_sge - 1)
* entries only. See also
* https://git.openfabrics.org/?p=compat-rdma/docs.git;a=blob;f=release_notes/mthca_release_notes.txt;h=40f3c4ea77a07fe5ded888b8417530471e89d87b;hb=1ebd1b1dd5b413be595a835bbcb644d2c8897f98.
*/
max_sge_delta = 1;
break;
default:
break;
}
#else
if (strncmp(dev_name(&sdev->device->dev), "mlx4_", 5) == 0)
max_sge_delta = 2;
else if (strncmp(dev_name(&sdev->device->dev), "mthca", 5) == 0)
max_sge_delta = 1;
#endif
pr_debug("max_sge_delta = %d\n", max_sge_delta);
}
/*
* For max_sge values > 2 * max_sge_delta, subtract max_sge_delta. For
* max_sge values < max_sge_delta, use max_sge. For intermediate
* max_sge values, use max_sge_delta.
*/
ch->max_send_sge -=
min_t(unsigned, max_sge_delta,
max_t(int, 0,
ch->max_send_sge - max_sge_delta));
qp_init->cap.max_send_sge = ch->max_send_sge;
qp_init->cap.max_recv_sge = 1;
if (sdev->use_srq) {
@@ -3306,6 +3263,7 @@ static int srpt_map_sg_to_ib_sge(struct srpt_rdma_ch *ch,
if (dir == SCST_DATA_WRITE) {
scst_cmd_get_write_fields(cmd, &sg, &sg_cnt);
WARN_ON(!sg);
max_sge = min(max_sge, ch->sport->sdev->dev_attr.max_sge_rd);
} else {
sg = scst_cmd_get_sg(cmd);
sg_cnt = scst_cmd_get_sg_cnt(cmd);