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Subject: Re: packet size vs inter-packet gap
From: jamal <hadi@cyberus.ca>
Reply-To: hadi@cyberus.ca
To: Lennert Buytenhek <buytenh@wantstofly.org>
Cc: Robert Olsson <Robert.Olsson@data.slu.se>,
        "David S. Miller" <davem@davemloft.net>, netdev@oss.sgi.com,
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Ah, try that on different pieces of h/ware. i.e 32/33, 64/66 and compare
before and after results. You may be suprised by the oddity;->

Actually, why not use patch i supplied?

cheers,
jamal

On Sat, 2004-11-27 at 17:06, Lennert Buytenhek wrote:
> (cc'ing netdev and e1000-devel)
> 
> 
> On Thu, Nov 25, 2004 at 11:49:45PM -0500, jamal wrote:
> 
> > Would be nice to see what happens when you kick the DMA only after
> > filling up the ring.
> 
> Just to 'confirm' what you've been seeing, even this tiny little patch:
> 
> diff -urN e1000.orig/e1000_main.c e1000/e1000_main.c
> --- e1000.orig/e1000_main.c	2004-11-24 15:35:23.000000000 +0100
> +++ e1000/e1000_main.c	2004-11-27 22:57:08.429782838 +0100
> @@ -1720,7 +1735,9 @@
>  	wmb();
>  
>  	tx_ring->next_to_use = i;
> +	if ((i % 4) == 0) {
>  	E1000_WRITE_REG(&adapter->hw, TDT, i);
> +	}
>  }
> 
> 
> changes my 60B TX rate numbers from:
>   612597pps
>   612447pps
>   612381pps
>   612568pps
>   612579pps
> 
> to:
>   614158pps
>   614179pps 
>   614186pps
>   614169pps
>   614171pps
>   614150pps
>   614180pps
>   614163pps
>   614179pps
> 
> (As before, 32/66, 82541PI, SMP Xeon 2.4, 2.6.9-something.)  'tis not
> much but definitely makes _some_ difference.
> 
> 
> cheers,
> Lennert
>