On Thu, 2014-05-29 at 20:29 +0000, Quinn Tran wrote:
> On 5/23/14 7:33 PM, "Nicholas A. Bellinger" <nab@xxxxxxxxxxxxxxx> wrote:
<SNIP>
> >> diff --git a/drivers/scsi/qla2xxx/tcm_qla2xxx.c
> >>b/drivers/scsi/qla2xxx/tcm_qla2xxx.c
> >> index 68fb66f..34db344 100644
> >> --- a/drivers/scsi/qla2xxx/tcm_qla2xxx.c
> >> +++ b/drivers/scsi/qla2xxx/tcm_qla2xxx.c
> >> @@ -1482,7 +1482,9 @@ static int tcm_qla2xxx_check_initiator_node_acl(
> >> }
> >> se_tpg = &tpg->se_tpg;
> >>
> >> - se_sess = transport_init_session(TARGET_PROT_NORMAL);
> >> + se_sess = transport_init_session_tags(TCM_QLA2XXX_DEFAULT_TAGS,
> >> + sizeof(struct qla_tgt_cmd),
> >> + TARGET_PROT_NORMAL);
> >> if (IS_ERR(se_sess)) {
> >> pr_err("Unable to initialize struct se_session\n");
> >> return PTR_ERR(se_sess);
> >> diff --git a/drivers/scsi/qla2xxx/tcm_qla2xxx.h
> >>b/drivers/scsi/qla2xxx/tcm_qla2xxx.h
> >> index 33aaac8..b0a3ea5 100644
> >> --- a/drivers/scsi/qla2xxx/tcm_qla2xxx.h
> >> +++ b/drivers/scsi/qla2xxx/tcm_qla2xxx.h
> >> @@ -4,6 +4,8 @@
> >> #define TCM_QLA2XXX_VERSION "v0.1"
> >> /* length of ASCII WWPNs including pad */
> >> #define TCM_QLA2XXX_NAMELEN 32
> >> +/* Number of pre-allocated per-session tags */
> >> +#define TCM_QLA2XXX_DEFAULT_TAGS 512
> >>
> >
> >So a question wrt to the TCM_QLA2XXX_DEFAULT_TAGS value above used to
> >determine the number of qla_tgt_cmd descriptors to pre-allocate at
> >qla_tgt_sess creation time..
> >
> >This value needs to line up with the total number of possible incoming
> >ATIO packets, plus the number of qla_tgt_cmd descriptors that have not
> >been acknowledged with a CTIO packet. Typically with other fabrics that
> >have been converted to use percpu_ida, we over-allocate the number of
> >per-session tags in order to completely avoid the slow-path where
> >percpu_ida has to steal tags from another CPU.
> >
> >AFAICT, there is no way at the qla_target driver level to enforce
> >per-session queue_depth + reflect the depth at the initiator port, so
> >the number of tags needs to be the worst case number of HW descriptors
> >that a single session can consume + number of unacknowledged
> >descriptors.
>
> QT> QLA driver & FW currently do not have queue_depth control at a per
> session level. Instead, the descriptor pool (i.e. Exchange pool) is manage
> by FW at the Port level.
>
> >
> >So the question is, is there already a define somewhere in qla2xxx code
> >that TCM_QLA2XXX_DEFAULT_TAGS can use as a starting point..? If not,
> >what is the total number of outstanding commands that a single session
> >(or single port..?) can expect to handle at a given time..?
>
> QT> Typically, the worst case value we see is 2048 for each port. It's
> currently not #define. This value can change over time. A good starting
> default value for TCM_QLA2XXX_DEFAULT_TAGS would be 2048 + %2 pad = 2088.
>
<nod>, thanks for the extra background.
> Extra size note, the true value should be extracted from
> "ha->fw_xcb_count", if this field is set. Otherwise, default back to
> TCM_QLA2XXX_DEFAULT_TAGS.
>
Ok, squashing the following patch into the original to use
ha->fw_xcb_count (if available) for determining the worst-case per
session number of tags. Note this currently ends up being ~1.7 MB of
pre-allocated descriptors per session.
Also, I assume the pad is required for ha->fw_xcb_count as well.. In
that case, the patch below also adds a extra define for 40 extra tags
following your pad comment above.
--nab
diff --git a/drivers/scsi/qla2xxx/tcm_qla2xxx.c b/drivers/scsi/qla2xxx/tcm_qla2xxx.c
index 34db344..8b7743f 100644
--- a/drivers/scsi/qla2xxx/tcm_qla2xxx.c
+++ b/drivers/scsi/qla2xxx/tcm_qla2xxx.c
@@ -1465,6 +1465,8 @@ static int tcm_qla2xxx_check_initiator_node_acl(
struct qla_tgt_sess *sess = qla_tgt_sess;
unsigned char port_name[36];
unsigned long flags;
+ int num_tags = (ha->fw_xcb_count) ? ha->fw_xcb_count :
+ TCM_QLA2XXX_DEFAULT_TAGS;
lport = vha->vha_tgt.target_lport_ptr;
if (!lport) {
@@ -1482,7 +1484,7 @@ static int tcm_qla2xxx_check_initiator_node_acl(
}
se_tpg = &tpg->se_tpg;
- se_sess = transport_init_session_tags(TCM_QLA2XXX_DEFAULT_TAGS,
+ se_sess = transport_init_session_tags(num_tags + TCM_QLA2XXX_PAD_TAGS,
sizeof(struct qla_tgt_cmd),
TARGET_PROT_NORMAL);
if (IS_ERR(se_sess)) {
diff --git a/drivers/scsi/qla2xxx/tcm_qla2xxx.h b/drivers/scsi/qla2xxx/tcm_qla2xxx.h
index b0a3ea5..04d6728 100644
--- a/drivers/scsi/qla2xxx/tcm_qla2xxx.h
+++ b/drivers/scsi/qla2xxx/tcm_qla2xxx.h
@@ -4,8 +4,12 @@
#define TCM_QLA2XXX_VERSION "v0.1"
/* length of ASCII WWPNs including pad */
#define TCM_QLA2XXX_NAMELEN 32
-/* Number of pre-allocated per-session tags */
-#define TCM_QLA2XXX_DEFAULT_TAGS 512
+/*
+ * Number of pre-allocated per-session tags, based upon the worst-case
+ * per port number of iocbs
+ */
+#define TCM_QLA2XXX_DEFAULT_TAGS 2048
+#define TCM_QLA2XXX_PAD_TAGS 40
#include "qla_target.h"
--
To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
