[parisc-linux] C110 builtin nic slow?

Joel Soete soete.joel@tiscali.be
Mon, 10 Nov 2003 15:00:37 +0100


Grant,

Sorry again, but having find this interesting stuff in 82596.c:
---------><---------
[...]
                        /* Check if the packet is long enough to just accept
                         * without copying to a properly sized skbuff.
                         */

                        if (pkt_len > rx_copybreak) {
                                struct sk_buff *newskb;
[...]
                        }
                        else
                                skb = dev_alloc_skb(pkt_len + 2);

[...]
---------><---------
This seems well what you describe?
and more:
---------><---------
[...]
/* Copy frames shorter than rx_copybreak, otherwise pass on up in
 * a full sized sk_buff.  Value of 100 stolen from tulip.c (!alpha).
 */
static int rx_copybreak = 100;
[...]
---------><---------
and finaly:
---------><---------
/*
[...]
   TBD:
   [...]
   * performace test to tune rx_copybreak
[...]
---------><---------

(I just copy as read preformace and not performance as my mind abuse :) )

This last notice seems what I am loocking for?
Have you a better idea then try and test (ie rx_copybreak=512, test, rx_copybreak=256,
... and btw rx_copybreak = PKT_BUF_SZ == 1536)?
Or is it better to tiddle code before?

Thanks for additional advise,
    Joel

>-- Original Message --
>From: "Joel Soete" <soete.joel@tiscali.be>
>To: "Grant Grundler" <grundler@parisc-linux.org>
>Cc: "parisc-linux" <parisc-linux@lists.parisc-linux.org>
>Date: Mon, 10 Nov 2003 13:31:45 +0100
>Subject: Re: [parisc-linux] C110 builtin nic slow?
>
>
>Sorry for auto-reply but I just remember that on the c110 the builtin nic
is:
"8. Raven T' Core LAN (802.3) (10) at 0xffd07000 [8/16/6], versions 0x32,

0x0, 0x8a"
ie a Lasi_82596 (as Matthew mentioned in a previous mail).

That you look for tha
> stuff in that code :)

Joel




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