Interrupt performance

Slawa Olhovchenkov slw at
Fri Jan 28 15:15:32 UTC 2011

I test network performance and found some strange result -- on the
same hardware Linux more then 10x used CPU resources for interrupt

FreeBSD system utilise 70% CPU (32% idle, 59% interrupt, 9% sys) and
network card generate 14K-18K interrupt per second.

Linux system utilise 20% CPU (80% idle, 13% system, 3% hiq, 4% siq)
and network card generate 56K interrupt per second.

I used 'netperf -H host -t UDP_STREAM -l 60 -C -c -- -m 8972 -s
128K -S 128K' for generate network traffic.


re0: <RealTek 8169SC/8110SC Single-chip Gigabit Ethernet> port 0x4000-0x40ff mem 0xf0100000-0xf01000ff irq 19 at device 4.0 on pci11
re0: Chip rev. 0x18000000
re0: MAC rev. 0x00000000
miibus0: <MII bus> on re0
rgephy0: <RTL8169S/8110S/8211B media interface> PHY 1 on miibus0


CPU: Intel(R) Celeron(R) CPU          420  @ 1.60GHz (1596.05-MHz K8-class CPU)
  Origin = "GenuineIntel"  Id = 0x10661  Family = 6  Model = 16
  Stepping = 1
  AMD Features=0x20100800<SYSCALL,NX,LM>
  AMD Features2=0x1<LAHF>
  TSC: P-state invariant

RAM: one DDR2-667 DIMM.

OS: 8.2-RC2, amd64

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