Re: Thread implementations...t

Alan Cox (alan@lxorguk.ukuu.org.uk)
Thu, 25 Jun 1998 21:23:31 +0100 (BST)


> Unless you need copying small fragments (let's say few pages) from one
> file to another. In such cases mmap/munmap is just too much overhead.

In the case where mmap is too much overhead so is the locking for a
kernel "copy*" operation quite honestly. What are the semantics of
send_file when some other process is DMAing into the buffer cache page
we have queued on the socket ?

> > Now the reason to have it is for NFS type systems that support copy
> > and copytree operations directly on the remote (eg SMB)
>
> Or maybe SCSI block copy commands, but it would be hard to implement
> for anything else than block devices.

SCSI block copy worries me. Nobody I know uses disk->disk SCSI facilities
which makes me suspect if we implement it drive firmware will die left
right and centre.

Alan [he of little faith]

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