Re: Route cache performance

[Simon Kirby <sim@xxxxxxxxxxxxx>]

On Wed, Sep 07, 2005 at 04:45:03PM +0200, Robert Olsson wrote:

>  Packet processing happens in RX_SOFIRQ. NAPI or non-NAPI is no difference
>  with RCU deferred delete this should happen by the RCU-tasklet when 
>  tasklets are run after the real SOFTIRQ's.
> 
>  There is a limit for RCU work... maxbatch it's set to 10  you could back 
>  out the patch and try increase it 1000/10000 so we know this not prevent 
>  the freeing of entries. 

Yes, setting maxbatch to 10000 also results in working gc, though routing
throughput is about 5.7% higher when just calling dst_free directly.

>  Also RCU clearly states that is should be used in read-mostly situations
>  rDoS is outside this scope. Anyway it would be interesting to understand 
>  what's going on.

There was discussion about this before (recycling of existing entries is
also now impossible, as compared with 2.4).  It's a shame that this win
for the normal case also hurts the DoS case...and it really hurts when
the when the DoS case is the normal case.

Simon-