On 11 February 2013 12:53, Dan Shechter <[email protected]> wrote: > Thanks, > > Are there any other tips to reduce latency? >
Using pcap means copying packets, so I'd say you want to put your code into the kernel to avoid copying and maybe queueing as well, but this is not something that can be trivially explained and is certainly not something that OpenBSD supports or would want to support out of the box. FreeBSD netmap interface would be helpful in your situation but is not currently supported by OpenBSD. Cheers, Mike > > Best regards, > Dan > > > On Mon, Feb 11, 2013 at 1:43 PM, Mike Belopuhov <[email protected]> wrote: >> On 11 February 2013 12:19, Dan Shechter <[email protected]> wrote: >>> Hi All, >>> >>> I have a very latency sensitive application. I need to move packets >>> from one interface to another >>> >>> I am using a quad 1000/pro Intel NIC. pcidump shows 82571EB >>> >>> My latency sensitive application reads packets from one em interface >>> using libpcap and sends packet to another em interface using udp >>> socket. >>> >>> Does em has interrupt mitigation enabled? >> >> It does. >> >>> If interrupt mitigation is enabled would disabling it will reduce latency? >> >> It would. >> >>> How can I disable the interrupt mitigation for em NICs? >> >> I suggest you try increasing MAX_INTS_PER_SEC define by the factor >> or two in /sys/dev/pci/if_em.h. In case it doesn't suite your needs you >> can try commenting out this line: >> >> E1000_WRITE_REG(&sc->hw, ITR, DEFAULT_ITR); >> >>> What would change in 5.3? >>> >> >> Nothing regarding interrupt moderation. >> >>> Best regards, >>> Dan >>> >> >> Cheers, >> Mike
