Re: tigon3: 2466 and bad performance at 32bits/33mhz ?

[Ben Greear <greearb@candelatech.com>]

Willy Tarreau wrote:
> On Tue, Aug 06, 2002 at 12:35:08AM -0500, Robert Latham wrote:
> 
>>The fast curve is with the 3c996B-T in the 64/66 slot.  It peaks out
>>around 850 Mbps.  The slow curve is the same card in the 32/33 slot.
>>It peaks around 180 Mbps.
> 
> [snip]
> 
>>So, am i looking at a hardware limitation?  driver quirk?  I'm open to
>>any suggestions.  
> 
> 
> on a 32/33 slot, with a quad fast ethernet card, I can reach 400 Mbps
> on good hardware. The *theorical* bandwidth limit is 1.06 Gbps for
> 32 bits/33 Mhz. Of course, there's some overhead, but you would need 80%
> overhead to get you numbers, not very likely...
> 
> Perhaps this slot is on another bus, perhaps the latency timer is too
> low and the card receives small chunks at once, or perhaps this bus
> is shared with another hungry device ?
> 
> Regards,
> willy

I'm pushing 650Mbps on a 32/33 PCI bus using a Netgear GA620 GigE
card (the card supports 64bit PCI).  So, its not exactly a PCI bus
limitation you are hitting unless your PCI chipset somehow really
sucks.

Ben

> 
> -
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
> 


-- 
Ben Greear <greearb@candelatech.com>       <Ben_Greear AT excite.com>
President of Candela Technologies Inc      http://www.candelatech.com
ScryMUD:  http://scry.wanfear.com     http://scry.wanfear.com/~greear