2006-08-18 18:55:36

by Ed L. Cashin

Subject: [PATCH 2.6.18-rc4] aoe [08/13]: improve retransmission heuristics

Signed-off-by: "Ed L. Cashin" <[email protected]>

Add a dynamic minimum timer for better retransmission behavior.

diff -upr 2.6.18-rc4-orig/drivers/block/aoe/aoe.h 2.6.18-rc4-aoe/drivers/block/aoe/aoe.h
--- 2.6.18-rc4-orig/drivers/block/aoe/aoe.h 2006-08-17 16:45:34.000000000 -0400
+++ 2.6.18-rc4-aoe/drivers/block/aoe/aoe.h 2006-08-17 16:45:34.000000000 -0400
@@ -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 -upr 2.6.18-rc4-orig/drivers/block/aoe/aoecmd.c 2.6.18-rc4-aoe/drivers/block/aoe/aoecmd.c
--- 2.6.18-rc4-orig/drivers/block/aoe/aoecmd.c 2006-08-17 16:45:34.000000000 -0400
+++ 2.6.18-rc4-aoe/drivers/block/aoe/aoecmd.c 2006-08-17 16:45:34.000000000 -0400
@@ -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 */


--
"Ed L. Cashin" <[email protected]>

2006-08-18 22:41:22

by Alan

Subject: Re: [PATCH 2.6.18-rc4] aoe [08/13]: improve retransmission heuristics

Ar Gwe, 2006-08-18 am 13:39 -0400, ysgrifennodd Ed L. Cashin:
> Signed-off-by: "Ed L. Cashin" <[email protected]>
>
> Add a dynamic minimum timer for better retransmission behavior.

Acked-by: Alan Cox <[email protected]>

"those who fail to learn from TCP are doomed to re-invent it, badly, at
the wrong level." - Tim Wright