John-Mark Gurney wrote: > Randall Stewart wrote this message on Fri, Sep 29, 2006 at 16:55 -0400: > >>Mike Silbersack wrote: >> >>>On Fri, 29 Sep 2006, Andre Oppermann wrote: >>> >>> >>> >>>>over it an copies the data into the mbufs by using uiomove(). >>>>sosend_dgram() >>>>and sosend_generic() are change to use m_uiotombuf() instead of >>>>sosend_copyin(). >>> >>> >>>Can you do some UDP testing with 512b, 1K, 2K, 4K, 8K, and 16K packets to >>>see if performance changes there as well? >> >>Hmm.. I would think 512b and 1K will not show any >>improvement.. since they would probably end up either >>in an mbuf chain.. or a single 2k (or maybe 4k) cluster.. >>... quite a waste.. now if we had 512b and 1k clusters that >>would be cool... >> >>In fact I have always thought we should: >> >>a) have no data portion in an mbuf.. just pointers i.e. always >> an EXT >> >>b) Have a 256/512 and 1k cluster too.. >> >>This would allow copy by reference no matter what size si >>being sent... > > > IMO it's quite a waste of memory the way we have thigns now, though > w/ TSO it'll change things... Receive path != send path. > w/ 512 byte mbuf and a 2k cluster just to store just 1514 bytes of data, > that's only 60% effeciency wrt to memory usage... so, we currently > waste 40% of memory allocated to mbufs+clusters... Even reducing > mbufs back to 128 or 256 would be a big help, though IPSEC I believe > would have issues... mbufs are 256 bytes. > Hmmm.. If we switched clusters to 1536 bytes in size, we'd be able to > fit 8 in 12k (though I guess for 8k page boxes we'd do 16 in 24k)... The > only issue w/ that would be that a few of the clusters would possibly > split page boundaries... How much this would effect performance would > be an interesting question to answer... Splitting page boundaries is not an option as it may not be physically contigous. Just don't overengineer the stuff. Mbufs are only used temporarily and a bit theoretical waste is not much a problem (so far at least). -- AndreReceived on Fri Sep 29 2006 - 19:59:35 UTC
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