For now we've mostly disabled dummynet and the drops have stopped,
thanks to some extra unused bandwidth we have. But this isn't a real
solution, of course, so this weekend I'm going to try the suggestion
made by Robert Watson:
> In the driver init code in if_bce, the following code appears:
>
> ifp->if_snd.ifq_drv_maxlen = USABLE_TX_BD;
> IFQ_SET_MAXLEN(&ifp->if_snd, ifp->if_snd.ifq_drv_maxlen);
> IFQ_SET_READY(&ifp->if_snd);
>
> Which evaluates to a architecture-specific value due to varying
pagesize. You might just try forcing it to 1024.
But I've looked in /sys/dev/bce/if_bcereg.h of our FreeBSD 7.1 source
code and found this:
#define TX_PAGES 2
#define TOTAL_TX_BD_PER_PAGE (BCM_PAGE_SIZE / sizeof(struct tx_bd))
#define USABLE_TX_BD_PER_PAGE (TOTAL_TX_BD_PER_PAGE - 1)
#define TOTAL_TX_BD (TOTAL_TX_BD_PER_PAGE * TX_PAGES)
#define USABLE_TX_BD (USABLE_TX_BD_PER_PAGE * TX_PAGES)
#define MAX_TX_BD (TOTAL_TX_BD - 1)
meaning that USABLE_TX_BD is expected to be smaller than MAX_TX_BD. What
if MAX_TX_BD is itself way smaller than 1024, which I'll eventually set
ifq_drv_maxlen to? Can a driver guru please comment on this? In a few
days I'm going to try it anyway, and if the system locks up I'll just
revert back to the original code, and order a darn expensive Intel 10
Gige card, but it won't hurt to ask beforehand.
TIA
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