Re: NAPI and tg3

From: Robert Olsson (Robert.Olsson@data.slu.se)
Date: Thu Jan 09 2003 - 12:21:00 EST


Before it's get forgotten...

Cheers.
                                                --ro

--- NAPI_HOWTO.txt.orig 2002-12-24 06:20:31.000000000 +0100
+++ NAPI_HOWTO.txt 2003-01-09 13:25:30.000000000 +0100
@@ -721,6 +721,23 @@
 
 
 
+
+APPENDIX 3: Scheduling issues.
+==============================
+As seen NAPI moves processing to softirq level. Linux uses the ksoftirqd as the
+general solution to schedule softirq's to run before next interrupt and by putting
+them under scheduler control. Also this prevents consecutive softirq's from
+monopolize the CPU. This also have the effect that the priority of ksoftirq needs
+to be considered when running very CPU-intensive applications and networking to
+get the proper balance of softirq/user balance. Increasing ksoftirq priority to 0
+(eventually more) is reported cure problems with low network performance at high
+CPU load.
+
+Most used processes in a GIGE router:
+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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