svn commit: r314584 - in stable/11: share/man/man4 sys/cam/ctl

[Alexander Motin]

Author: mav
Date: Fri Mar  3 06:06:27 2017
New Revision: 314584
URL: https://svnweb.freebsd.org/changeset/base/314584

Log:
  MFC r313854, r313963: Change the way MaxCmdSN is used.
  
  Before this change MaxCmdSN was reported as CmdSN + delta, that made it
  limit number of requests in transmission from the initiator to target,
  that was pretty useless.  After this change MaxCmdSN limits number of
  requests queued to CTL, i.e. maximal queue depth for the initiator.
  The default limit is 256 outstanding requests per initiator at a time.
  
  This code uses existing cs_outstanding_ctl_pdus counter to track queue
  depth.  It's semantics doen't perfectly match, but close enough to not
  add another counter.  Just don't set the maxtags below 2.

Modified:
  stable/11/share/man/man4/ctl.4
  stable/11/sys/cam/ctl/ctl_frontend_iscsi.c
Directory Properties:
  stable/11/   (props changed)

Modified: stable/11/share/man/man4/ctl.4
==============================================================================
--- stable/11/share/man/man4/ctl.4	Fri Mar  3 06:04:42 2017	(r314583)
+++ stable/11/share/man/man4/ctl.4	Fri Mar  3 06:06:27 2017	(r314584)
@@ -24,7 +24,7 @@
 .\" SUCH DAMAGE.
 .\"
 .\" $FreeBSD$
-.Dd September 27, 2015
+.Dd January 19, 2017
 .Dt CTL 4
 .Os
 .Sh NAME
@@ -158,10 +158,9 @@ Verbosity level for log messages from th
 Set to 0 to disable logging or 1 to warn about potential problems.
 Larger values enable debugging output.
 Defaults to 1.
-.It Va kern.cam.ctl.iscsi.maxcmdsn_delta
-The number of outstanding commands to advertise to the iSCSI initiator.
-Technically, it is the difference between ExpCmdSN and MaxCmdSN fields
-in the iSCSI PDU.
+.It Va kern.cam.ctl.iscsi.maxtags
+The number of outstanding commands to advertise to each iSCSI initiator.
+Current implementation is not very accurate, so do not set this below 2.
 Defaults to 256.
 .It Va kern.cam.ctl.iscsi.ping_timeout
 The number of seconds to wait for the iSCSI initiator to respond to a NOP-In

Modified: stable/11/sys/cam/ctl/ctl_frontend_iscsi.c
==============================================================================
--- stable/11/sys/cam/ctl/ctl_frontend_iscsi.c	Fri Mar  3 06:04:42 2017	(r314583)
+++ stable/11/sys/cam/ctl/ctl_frontend_iscsi.c	Fri Mar  3 06:06:27 2017	(r314584)
@@ -95,10 +95,9 @@ SYSCTL_INT(_kern_cam_ctl_iscsi, OID_AUTO
 static int login_timeout = 60;
 SYSCTL_INT(_kern_cam_ctl_iscsi, OID_AUTO, login_timeout, CTLFLAG_RWTUN,
     &login_timeout, 60, "Time to wait for ctld(8) to finish Login Phase, in seconds");
-static int maxcmdsn_delta = 256;
-SYSCTL_INT(_kern_cam_ctl_iscsi, OID_AUTO, maxcmdsn_delta, CTLFLAG_RWTUN,
-    &maxcmdsn_delta, 256, "Number of commands the initiator can send "
-    "without confirmation");
+static int maxtags = 256;
+SYSCTL_INT(_kern_cam_ctl_iscsi, OID_AUTO, maxtags, CTLFLAG_RWTUN,
+    &maxtags, 0, "Max number of requests queued by initiator");
 
 #define	CFISCSI_DEBUG(X, ...)						\
 	do {								\
@@ -244,7 +243,7 @@ cfiscsi_pdu_update_cmdsn(const struct ic
 		 * outside of this range.
 		 */
 		if (ISCSI_SNLT(cmdsn, cs->cs_cmdsn) ||
-		    ISCSI_SNGT(cmdsn, cs->cs_cmdsn + maxcmdsn_delta)) {
+		    ISCSI_SNGT(cmdsn, cs->cs_cmdsn - 1 + maxtags)) {
 			CFISCSI_SESSION_UNLOCK(cs);
 			CFISCSI_SESSION_WARN(cs, "received PDU with CmdSN %u, "
 			    "while expected %u", cmdsn, cs->cs_cmdsn);
@@ -399,7 +398,8 @@ cfiscsi_pdu_prepare(struct icl_pdu *resp
 	    (bhssr->bhssr_flags & BHSDI_FLAGS_S))
 		bhssr->bhssr_statsn = htonl(cs->cs_statsn);
 	bhssr->bhssr_expcmdsn = htonl(cs->cs_cmdsn);
-	bhssr->bhssr_maxcmdsn = htonl(cs->cs_cmdsn + maxcmdsn_delta);
+	bhssr->bhssr_maxcmdsn = htonl(cs->cs_cmdsn - 1 +
+	    imax(0, maxtags - cs->cs_outstanding_ctl_pdus));
 
 	if (advance_statsn)
 		cs->cs_statsn++;