On Thu, Jul 11, 2002 at 04:42:25PM -0400, Bosko Milekic wrote:
...
> > and trimming away the refcount area might easily result in suboptimal
> > allocation of storage within the kernel.
>
> Can you elaborate on the sub-optimal performance comment with,
> perhaps, an example? I'm sorry but I'm sometimes slow to understand
example: userland does an 8KB write, in the old case this requires
4 clusters, with the new one you end up using 4 clusters and stuff
the remaining 16 bytes in a regular mbuf, then depending on the
relative producer-consumer speed the next write will try to fill
the mbuf and attach a new cluster, and so on... and when TCP hits
these data-in-mbuf blocks will have to copy rather than reference
the data blocks...
Maybe it is irrelevant for performance, maybe it is not,
i am not sure.
> The problem with this approach is that I'm probably going to be
> allocating jumbo bufs from the same map, in which case you would have
> huge `gaps' in your address <-> ref. count location map and, as a
how huge ? and do you really need to use the same map rather than
two different ones ?
cheers
luigi
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