aoe: improve retransmission heuristics

Add a dynamic minimum timer for better retransmission behavior.

Signed-off-by: "Ed L. Cashin" <ecashin@coraid.com>
Acked-by: Alan Cox <alan@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

2 files changed, 17 insertions, 6 deletions

diff --git a/drivers/block/aoe/aoe.h b/drivers/block/aoe/aoe.h
index 4d79f1eaf708..7b1121748633 100644
--- a/drivers/block/aoe/aoe.h
+++ b/drivers/block/aoe/aoe.h
@@ -125,8 +125,10 @@ struct aoedev {
         ulong sysminor;
         ulong aoemajor;
         ulong aoeminor;
-        ulong nopen;            /* (bd_openers isn't available without sleeping) */
-        ulong rttavg;           /* round trip average of requests/responses */
+        u16 nopen;              /* (bd_openers isn't available without sleeping) */
+        u16 lasttag;            /* last tag sent */
+        u16 rttavg;             /* round trip average of requests/responses */
+        u16 mintimer;
         u16 fw_ver;             /* version of blade's firmware */
         u16 maxbcnt;
         struct work_struct work;/* disk create work struct */
@@ -142,7 +144,6 @@ struct aoedev {
         mempool_t *bufpool;     /* for deadlock-free Buf allocation */
         struct list_head bufq;  /* queue of bios to work on */
         struct buf *inprocess;  /* the one we're currently working on */
-        ulong lasttag;          /* last tag sent */
         ushort lostjumbo;
         ushort nframes;         /* number of frames below */
         struct frame *frames;
diff --git a/drivers/block/aoe/aoecmd.c b/drivers/block/aoe/aoecmd.c
index 621fdbbc4cd4..c0bdc1fe21f0 100644
--- a/drivers/block/aoe/aoecmd.c
+++ b/drivers/block/aoe/aoecmd.c
@@ -461,8 +461,15 @@ calc_rttavg(struct aoedev *d, int rtt)
         register long n;
 
         n = rtt;
-        if (n < MINTIMER)
-                n = MINTIMER;
+        if (n < 0) {
+                n = -rtt;
+                if (n < MINTIMER)
+                        n = MINTIMER;
+                else if (n > MAXTIMER)
+                        n = MAXTIMER;
+                d->mintimer += (n - d->mintimer) >> 1;
+        } else if (n < d->mintimer)
+                n = d->mintimer;
         else if (n > MAXTIMER)
                 n = MAXTIMER;
 
@@ -498,8 +505,10 @@ aoecmd_ata_rsp(struct sk_buff *skb)
 
         spin_lock_irqsave(&d->lock, flags);
 
-        f = getframe(d, be32_to_cpu(hin->tag));
+        n = be32_to_cpu(hin->tag);
+        f = getframe(d, n);
         if (f == NULL) {
+                calc_rttavg(d, -tsince(n));
                 spin_unlock_irqrestore(&d->lock, flags);
                 snprintf(ebuf, sizeof ebuf,
                         "%15s e%d.%d    tag=%08x@%08lx\n",
@@ -724,6 +733,7 @@ aoecmd_cfg_rsp(struct sk_buff *skb)
                 return;
         }
         d->flags |= DEVFL_PAUSE;        /* force pause */
+        d->mintimer = MINTIMER;
         d->fw_ver = be16_to_cpu(ch->fwver);
 
         /* check for already outstanding ataid */