On Tue, Mar 09, 2010 at 11:55:30PM +0200, Ian FREISLICH wrote: > Pyun YongHyeon wrote: > > On Tue, Mar 09, 2010 at 03:31:55PM +0200, Ian FREISLICH wrote: > > > Can you explain the tunables please - I'm guessing it's these: > > I think I asked the wrong question. What is a "Quick BD Chain"?
I don't know why Broadocom uses 'Quick'. It's a just buffer descriptor chain for TX/RX. > What relation should this number have to traffic rate. Is there a > maximum and what are reasonable numbers for setting this to? > The maximum BD chain would be number of configured TX/RX descriptors. And 1 would be minimum value as you have to want to get status block for each TX/RX. Finding best value may depend on specific load. > I set the RX as high as 512 in 64 quanta but it made little difference > to the interrupt rate. At times where we experience the packet > loss and com_no_buffers increases, the interrupt rate on between 1 > and 3 of the 4 bce interfaces fell from about 3200/s to 130/s. > BD chain is just one of parameters. bce(4) controllers also provide more advanced features that fine control interrupt moderation(TX/RX ticks). It's hard to explain all the details so you may want to read public data sheet of bce(4). http://www.broadcom.com/collateral/pg/NetXtremeII-PG203-R.pdf See host coalescing registers(page 484). > We're wondering if the switches we're using could be causing this > problem - they're Dell PowerConnect 5448. I've seen complaints of > random packet loss caused by these switches on the Internet. We > have some new H3C 5100 series switches which we're planning on > swapping for the Dells tomorrow to see if it makes a difference. > Not sure but it does not explain increasing dev.bce.X.com_no_buffers counter. > Ian > > -- > Ian Freislich _______________________________________________ freebsd-current@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to "freebsd-current-unsubscr...@freebsd.org"
