Messages in this thread | | | Date | Thu, 3 Jun 1999 00:48:07 +0200 (MET DST) | From | Bjorn Wesen <> | Subject | Re: zero-copy TCP fileserving |
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On Wed, 2 Jun 1999, Oliver Xymoron wrote: > On Wed, 2 Jun 1999, Bjorn Wesen wrote: > > Speaking of shortcuts, what is the status of some sort of direct > > page -> skb TCP sending ? > > This simple zero-copy isn't really a win on most PC hardware as it takes > about the same amount of time to do a checksum as it does to do a checksum > and copy.
But for the hardware I'm running this on, a checksum + copy takes at least twice the time as a checksum (simple - read vs read/write). And this is the main bottleneck. Sure, on a P2/400 this is not an issue but it is for other systems, like embedded ones trying to run at 100 mbit/s.
> A more powerful scheme is being investigated by sct and a couple others. A > related scheme worked out on FreeBSD and presented at a recent Usenix > could cache checksums, for example.
Doesn't get rid of the unnecessary copying though.
/Bjorn
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