On 05/20/2010 05:19 PM, Eugene Grosbein wrote:
On 20.05.2010 13:06, rihad wrote:
Some more useful tunnables for loader.conf:
dev.em.0.rx_int_delay=200
dev.em.0.tx_int_delay=200
dev.em.0.rx_abs_int_delay=200
dev.em.0.tx_abs_int_delay=200
dev.em.0.rx_processing_limit=-1
So this interrupt delay is the much talked about interrupt moderation?
Thanks, I'll try them. Is there any risk the machine won't boot with
them if rebooted remotely?
Yes, for hw.em.rxd/hw.em.txd only. em interfaces will not function
if you set these two too high for your nic chip, so read man em
and mentioned Intel document carefully.
It's pretty safe to play with other tunnables.
Can I even set the mentioned dev.em.0.* settings on a live system
remotely? You seem to also have an em card, have you tried doing that?
Yes, it is permitted.
I haven't tweaked rx_abs_int_delay yet, but I've read the Intel specs
that you suggested. It says in the paragraph 4.4:
"The expected network use. High use implies high traffic rates, which
makes the GbE controller more susceptible to overrun conditions if it
delays interrupts too long."
Doesn't this mean that increasing the absolute timer (rx_abs_int_delay)
would only aggravate the issue and the Ierrs will only increase? It's
currently 66, by default I think:
dev.em.0.rx_int_delay: 0
dev.em.0.tx_int_delay: 66
dev.em.0.rx_abs_int_delay: 66
dev.em.0.tx_abs_int_delay: 66
I'm pretty sure interrupt overload is not an issue on our system:
Here's what top -HS currently shows:
12 root 171 ki31 0K 16K CPU2 2 174.3H 100.00% idle: cpu2
14 root 171 ki31 0K 16K CPU0 0 168.9H 99.76% idle: cpu0
11 root 171 ki31 0K 16K RUN 3 150.4H 94.19% idle: cpu3
13 root 171 ki31 0K 16K RUN 1 118.1H 73.97% idle: cpu1
27 root -68 - 0K 16K - 1 70.1H 31.88% em0 taskq
42 root -68 - 0K 16K - 3 30.5H 7.57% dummynet
The interrupt load is only 31% for em0.
So, hw.em.rxd=4096 seems to be the only way out? Increasing the buffer size.
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