[ovs-dev] [PATCH] datapath: Compute checksum while sending packets to userspace().

Ben Pfaff blp at nicira.com
Fri Jun 18 23:40:52 UTC 2010


On Fri, Jun 18, 2010 at 04:13:28PM -0700, Jesse Gross wrote:
> On Fri, Jun 18, 2010 at 3:31 PM, Ben Pfaff <blp at nicira.com> wrote:
> > This patch adds some complication, and as such it has some risks,
> > including the risk of the code being harder to understand and modify in
> > the future.  In exchange I'd normally expect there to be significant
> > benefits in compensation.  But I'm not sure that there are enough: I
> > doubt that the cost of checksumming packets sent down to userspace is
> > ever very high.  What do you think?
> 
> That thought did occur to me and it really depends on what you are doing.
>  As a percentage of the total cost of sending a packet to userspace,
> checksumming is fairly high.  So if you doing something that involves
> sending a lot of packets to userspace it is probably worth it, if not then
> it obviously isn't.

I guess it's up to you whether you think it's worthwhile overall.  You
do most of the kernel work these days, so it will probably be you
finding and fixing the bugs :-)




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