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Re: NetBSD 5.1 TCP performance issue (lots of ACK)

On Fri, Oct 28, 2011 at 04:10:36PM +0200, Manuel Bouyer wrote:
> Here is an updated patch. The key point to avoid the receive errors is
> to do another BUS_DMASYNC after reading wrx_status, before reading the
> other values to avoid reading e.g. len before status gets updated.
> The errors were because of 0-len receive descriptors.
> With this I get 113MB/s with the ttcp test, and between 70 and 90MB/s
> with glusterfs. the NetBSD client now gets the same speed with a
> NetBSD or linux server.
> In the patch there is changes for the WM_F_NEWQUEUE adapters but they
> may not be correct. When using WM_F_NEWQUEUE for the i80003 (which
> the linux driver does), performances are a little lower and I get
> a high interrupt rate - just as if interrupt mitigation was not
> working.

I'd say turn off WM_F_NEWQUEUE -- assuming that works -- and commit.

While you're in there, can you see whether we're actually feeding
the TSO enough data at once that it's actually useful?  The tcpdump
makes me suspect for some reason, we may not be.


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