Author: trasz
Date: Tue Apr  1 22:03:03 2014
New Revision: 264025
URL: http://svnweb.freebsd.org/changeset/base/264025

Log:
  Get rid of the "autoscaling", instead just set socket buffer sizes
  in the usual way.  The only thing the old code did was making things
  less predictable.
  
  Sponsored by: The FreeBSD Foundation

Modified:
  head/sys/dev/iscsi/icl.c

Modified: head/sys/dev/iscsi/icl.c
==============================================================================
--- head/sys/dev/iscsi/icl.c    Tue Apr  1 21:54:20 2014        (r264024)
+++ head/sys/dev/iscsi/icl.c    Tue Apr  1 22:03:03 2014        (r264025)
@@ -68,6 +68,14 @@ TUNABLE_INT("kern.icl.partial_receive_le
 SYSCTL_INT(_kern_icl, OID_AUTO, partial_receive_len, CTLFLAG_RW,
     &partial_receive_len, 1 * 1024, "Minimum read size for partially received "
     "data segment");
+static int sendspace = 1048576;
+TUNABLE_INT("kern.icl.sendspace", &sendspace);
+SYSCTL_INT(_kern_icl, OID_AUTO, sendspace, CTLFLAG_RW,
+    &sendspace, 1048576, "Default send socket buffer size");
+static int recvspace = 1048576;
+TUNABLE_INT("kern.icl.recvspace", &recvspace);
+SYSCTL_INT(_kern_icl, OID_AUTO, recvspace, CTLFLAG_RW,
+    &recvspace, 1048576, "Default receive socket buffer size");
 
 static uma_zone_t icl_conn_zone;
 static uma_zone_t icl_pdu_zone;
@@ -1008,7 +1016,7 @@ icl_conn_free(struct icl_conn *ic)
 static int
 icl_conn_start(struct icl_conn *ic)
 {
-       size_t bufsize;
+       size_t minspace;
        struct sockopt opt;
        int error, one = 1;
 
@@ -1029,18 +1037,28 @@ icl_conn_start(struct icl_conn *ic)
        ICL_CONN_UNLOCK(ic);
 
        /*
-        * Use max available sockbuf size for sending.  Do it manually
-        * instead of sbreserve(9) to work around resource limits.
+        * For sendspace, this is required because the current code cannot
+        * send a PDU in pieces; thus, the minimum buffer size is equal
+        * to the maximum PDU size.  "+4" is to account for possible padding.
         *
-        * XXX: This kind of sucks.  On one hand, we don't currently support
-        *      sending a part of data segment; we always do it in one piece,
-        *      so we have to make sure it can fit in the socket buffer.
-        *      Once I've implemented partial send, we'll get rid of this
-        *      and use autoscaling.
+        * What we should actually do here is to use autoscaling, but set
+        * some minimal buffer size to "minspace".  I don't know a way to do
+        * that, though.
         */
-        bufsize = (sizeof(struct iscsi_bhs) +
-            ic->ic_max_data_segment_length) * 8;
-       error = soreserve(ic->ic_socket, bufsize, bufsize);
+       minspace = sizeof(struct iscsi_bhs) + ic->ic_max_data_segment_length +
+           ISCSI_HEADER_DIGEST_SIZE + ISCSI_DATA_DIGEST_SIZE + 4;
+       if (sendspace < minspace) {
+               ICL_WARN("kern.icl.sendspace too low; must be at least %jd",
+                   minspace);
+               sendspace = minspace;
+       }
+       if (recvspace < minspace) {
+               ICL_WARN("kern.icl.recvspace too low; must be at least %jd",
+                   minspace);
+               recvspace = minspace;
+       }
+
+       error = soreserve(ic->ic_socket, sendspace, recvspace);
        if (error != 0) {
                ICL_WARN("soreserve failed with error %d", error);
                icl_conn_close(ic);
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