On Wed, 2005-07-12 at 11:48 -0800, John Ronciak wrote: > On 12/7/05, Jeff Garzik <[EMAIL PROTECTED]> wrote: > > > So... under load, copybreak causes e1000 to fall over more rapidly than > > no-copybreak? > > > > If so, it sounds like copybreak should be disabled by default, and/or a > > runtime switched added for it. > I wouldn't say "fall over". With small packet only tests (the ones > being run for this exercise) _all_ packets are being copied which is > why when the system become CPU bound you see performance drop. Normal > cases don't only have small packets and is where the gains are. These > are also what is not being tested because I'm sure nobody would be > able to agree on an acceptable test for it. Copybreak probably > shouldn't be used in routing use cases. Since I think routing is the > special case and not the normal case copybreak should be on by default > and disabled when used in cases like small packet routing is being > done.
I am no longer sure that your results on copybreak for host bound packets can be trusted anymore. All your copybreak was doing was making the prefetch look good according to my tests. Eric Dumazet <[EMAIL PROTECTED]> theorized there may be some value in copybreak if you are host bound. I only seen it as an unnecessary pain really. Humor me, try to replace the code that does copybreak with a while loop that counts down from 20 -> 0. And see if you notice any changes for host bound traffic. cheers, jamal - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
