Messages in this thread | | | From | Robert Olsson <> | Date | Tue, 7 Jan 2003 23:21:08 +0100 | Subject | Re: NAPI and tg3 |
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Steffen Persvold writes:
> True, but it doesn't say that if you have two applications loaded on > a SMP box, one which is for example constantly receiving and sending data > from/to the network and doing computations on the data (100 % CPU) while > some other app is only doing computations (also 100 % CPU), the ksoftirqd > which should receive packets and refill the TX and RX rings will be put > last in the queue because of its low nice level (19), thus the network > dependent application has very much lower performance than what could be > achieved with a nice level of 0 or even running the interrupt based > mechanism. A nice level of 0 on ksoftirqd is still a heck of a lot better > than interrupt context isn't it ?
Yes my scripts test/production has even been setting -19 to ksoftirq just for that reason so I almost forgot this issue so I'm happy you brought this up. But dev->poll is not the only user of ksoftirq but for heavy networking it's gets pretty dominant. So we add something to NAPI_HOWTO and pass the question about ksoftirq default priority to others.
From a GIGE router in production.
USER PID %CPU %MEM SIZE RSS TTY STAT START TIME COMMAND root 3 0.2 0.0 0 0 ? RWN Aug 15 602:00 (ksoftirqd_CPU0) root 232 0.0 7.9 41400 40884 ? S Aug 15 74:12 gated
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