Re: state of rtcache removal...

From: Tom Herbert <redacted>
Date: Wed, 16 Feb 2011 18:59:35 -0800

On Wed, Feb 16, 2011 at 4:08 PM, David Miller [off-list ref] wrote:

quoted

So I've been testing out the routing cache removal patch to see
what the impact is on performance.

Interesting results.

I assume that this test is purposely using sento on a connected socket
to force sendmsg to go through the route lookup :-), so this is
showing what the benefits of rtcache are is when cache hit rate is
100%.  For comparison, it might interesting to see what the
performance is when rate is < 100%.  For instance, we often see hit
rates < 20% on front end servers.  This could be done flooding to
random addresses in 10/8 or even 0/0...  I'm hoping that without the
rtcache performance actually improves in that case!

We know that the performance will be higher in the "closer to %0"
situation, ie.  for DoS workloads.  Because all of the route cache
management overhead goes away.

Anyways I'm working on some ideas to make the high hit rate case
perform amicably again.