On Friday, November 18, 2011 3:46:02 am Matteo Landi wrote: > > you probably want to be using MSI-X for a 10G NIC instead of INTx anyway. > > Why do you say that? Is MSI-X faster than INTx in terms of interrupt > latency? When should I use MSI-X, instead of fast filters interrupts > (fast interrupt?), instead of ithread interrupts? Thanks in advace.
With MSI-X you can have more than one interrupt and those interrupts can be distributed across CPUs. This means you can (somewhat) tie each queue on your NIC to a different CPU. MSI-X vs INTx is orthogonal to fast vs filter, but in general MSI and MSI-X interrupts are not shared, and require no interrupt masking in hardware (they are effectively edge-triggered), so using a filter for MSI is rather pointless and only adds needless complexity. For MSI I would just use a theraded interrupt handler. For INTx, I would only use a fast interrupt handler if there is a really good reason to do so (e.g. em(4) does so to work around broken Intel Host-PCI bridges). -- John Baldwin _______________________________________________ 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"
