[time-nuts] PCI-E Serial Card For Windows NTP?
brayniac at gmail.com
Thu Jun 25 21:55:02 EDT 2015
Trying not to go offtopic. If there are specific lists for this type of
nuttery, contact me off list - would love to learn and discuss more.
That said - if you're going to test the impact on latency for interrupt
coalescing, I'd suggest using sockperf ping pong test:
Should reveal a bit more than a simple icmp ping test can. Use the --pps
flag to test a variety of packet rates. Should help show the effect of
On Thu, Jun 25, 2015 at 13:40 Hal Murray <hmurray at megapathdsl.net> wrote:
> I know next-to-nothing about Windows.
> Serial ports are pretty standard. I'd get the cheapest card. I'd probably
> pay a bit more for a second port. It might be handy tomorrow.
> One difference between chips is the depth of the FIFO.
> PCI card now come in two heights. Make sure you get the right one. The
> short ones don't have room for a second connector. (Some cards come with
> face plates. You can swap in/out the other one if you can use a
> The other thing to keep an eye on is interrupts from the Gigabit ethernet.
> With a lot of short packets, you can get in trouble spending all your CPU
> time in the interrupt handler. Some hardware is setup to batch interrupts.
> The idea is to delay an interrupt for a while in hopes that more packets
> arrive and get processed as a batch. You may want to turn that off. It's
> tradeoff between latency and CPU usage. You may be able to measure it with
> something like ping.
> These are my opinions. I hate spam.
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