Subject: Re: bad TSO performance in 2.6.9-rc2-BK

From: Andi Kleen <[email-masked]>
Date: Thu, 23 Sep 2004 00:06:28 +0200

> One thing that could be biting us is the nagle check which
> probably needs to be adjusted to use the standard MSS not
> the TSO one... perhaps play with this patch:

I tried it and it breaks the performance completely
(21MB/s) 

-Andi

> 
> ===== include/net/tcp.h 1.88 vs edited =====
> --- 1.88/include/net/tcp.h	2004-09-14 13:57:07 -07:00
> +++ edited/include/net/tcp.h	2004-09-22 13:18:43 -07:00
> @@ -1505,7 +1505,7 @@
>  	 * final FIN frame.  -DaveM
>  	 */
>  	return (((nonagle&TCP_NAGLE_PUSH) || tp->urg_mode
> -		 || !tcp_nagle_check(tp, skb, cur_mss, nonagle)) &&
> +		 || !tcp_nagle_check(tp, skb, tp->mss_cache_std, nonagle)) &&
>  		(((tcp_packets_in_flight(tp) + (pkts-1)) < tp->snd_cwnd) ||
>  		 (TCP_SKB_CB(skb)->flags & TCPCB_FLAG_FIN)) &&
>  		!after(TCP_SKB_CB(skb)->end_seq, tp->snd_una + tp->snd_wnd));
> 
>