Re: 0% cpu usasge after fresh boot or net restart but 10% CPU if kernel flush route cache

Eric Dumazet
2010-01-28T16:09:24Z

Le jeudi 28 janvier 2010 à 11:14 +0200, cold cold a écrit :

>
> RX Kpps : 57 TX Kpps : 53 RX Kbits : 331184 TX Kbits : 306213
> RX Kpps : 59 TX Kpps : 54 RX Kbits : 345517 TX Kbits : 304323
> RX Kpps : 56 TX Kpps : 52 RX Kbits : 331418 TX Kbits : 296032
> RX Kpps : 60 TX Kpps : 54 RX Kbits : 362007 TX Kbits : 297371
> RX Kpps : 59 TX Kpps : 52 RX Kbits : 360455 TX Kbits : 280603
>
>
> ON one cpu, gc_interval to 1, gc_elasticity 2
>
> Cpu0 : 0.0%us, 0.0%sy, 0.0%ni, 72.0%id, 0.0%wa, 8.3%hi, 19.7%si, 0.0%st
> Cpu1 : 0.0%us, 0.0%sy, 0.0%ni,100.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
> Cpu2 : 0.0%us, 0.3%sy, 0.0%ni, 99.7%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
> Cpu3 : 0.0%us, 0.0%sy, 0.0%ni,100.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
>
> ------------------------------------------------------------------------------
> PerfTop: 17064 irqs/sec kernel:98.0% [100000 cycles], (all, 4 CPUs)
> ------------------------------------------------------------------------------
>
> samples pcnt kernel function
> _______ _____ _______________
>
> 40388.00 - 27.8% : acpi_idle_do_entry
> 24651.00 - 17.0% : read_hpet
> 4271.00 - 2.9% : _spin_lock
> 3388.00 - 2.3% : pskb_expand_head
> 3288.00 - 2.3% : igb_poll [igb]
> 3246.00 - 2.2% : irq_entries_start
> 2868.00 - 2.0% : dev_gro_receive
> 2665.00 - 1.8% : igb_xmit_frame_adv [igb]
> 2513.00 - 1.7% : ip_route_input
> 2144.00 - 1.5% : igb_clean_tx_irq [igb]
> 1842.00 - 1.3% : __slab_free
> 1544.00 - 1.1% : dev_queue_xmit
> 1423.00 - 1.0% : igb_msix_rx [igb]
> 1353.00 - 0.9% : __alloc_skb
> 1285.00 - 0.9% : eth_type_trans
> --

All this seems pretty normal profile (regarding networking functions),
your machine should scale without problem.

Of course, the two first functions (acpi_idle_do_entry() & read_hpet())
look suspicious but I have no idea why.