On Tue, Dec 18, 2007 at 09:05:41PM -0500, Patrick Geoffray wrote: > No, it just means the NIC supports it.
Well, then how about ethtool -S? That looks like an actual count of flow control events, so rx flow control events means the switch must support it in some fashion. > For RX hardware flow-control, you need enough buffer space to keep one > full frame plus the latency on the longest wire, for every port. It is a > bit more expensive to do with 10GigE, because you need faster memory and > more of it. Some recent 10GigE chips use a shared SRAM buffer that is > not big enough for the worst case with 9K packets: Well, we know it can be done perfectly, it's done in InfiniBand switches, and that other 10 gig non-ethernet switch, what's it called? Oh yeah, Myrinet. They do it, too. > Flow-control is not for everyone, and that's why it is often turned off > by default. When a sender is paused, it will stop sending anything, > including packets for different destinations. Dropping packets is > expensive to recover but it keeps things moving. Can Myrinet even disable flow control? Odd that Ethrernet is any different; dropping any packets is an utter disaster for TCP. -- greg _______________________________________________ Beowulf mailing list, [email protected] To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
