Date: Wed, 20 Nov 2002 12:41:53 -0500 From: Don Bowman <don@sandvine.com> To: 'Terry Lambert' <tlambert2@mindspring.com>, hiten@unixdaemons.com Cc: tony@ubik.demon.co.uk, freebsd-hackers@freebsd.org Subject: RE: if_ti DEVICE_POLLING patch (Was: Re: [hackers] Re: Netgraphc ouldbe a router also) Message-ID: <FE045D4D9F7AED4CBFF1B3B813C8533701022FB8@mail.sandvine.com>
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> From: Terry Lambert [mailto:tlambert2@mindspring.com]
> Hiten Pandya wrote:
> > Hehe. I was not being sarcastic. I just acknoledged your
> statement. The
> > reason I asked about committing the patch in the first
> place, is because I
> > thought that the patch had been around on the -net@ list,
> and had been reviewed.
> >
> > My apologies.
>
> It's been around on the list for a while, but if it's working for
> the people involved, they are not saying anything.
>
> Last I heard, the person who had the problem had tried the Intel
> Gigabit card, but not the Tigon III, but was looking for a Gigabit
> card recommendation.
>
> I suppose I could make the same patch for the Intel card.
>
> The problem is that DEVICE_POLLING is an all-or-nothing thing,
> you can't control it on a card-by-card basis, even with a
> sysctl, because it fills out an entry point that's statically,
> rather than procedurally initialized.
Is there any point to using device polling with the tigon 3
(broadcom 570x etc)? It has a pretty good interrupt reducer in it
by itself.
Just tune the 2 rx and the 2 tx parameters and you get a constant
interrupt rate with good latency for any packet rate.
I changed (if_bge.c):
/* RX Interrupt no more than every ~500 us */
sc->bge_rx_coal_ticks = 512;
/* TX Interrupt no more than every ~500 us */
sc->bge_tx_coal_ticks = 512;
/* RX Interrupt no more than every ~120 packets */
sc->bge_rx_max_coal_bds = 128;
/* TX Interrupt no more than every ~120 packets */
sc->bge_tx_max_coal_bds = 128;
and this gives no more than 2000 interrupts/s, and no more than 500us
of latency.
The if_em has similar functionality AFAIK.
--don
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