Re: [PATCH 1/3] copyfile: generic_sendpage

[Jörn Engel]

On Mon, 6 September 2004 14:45:38 +0200, Gunnar Ritter wrote:
> 
> It is an even more serious problem in my experience. I have been
> using sendfile() in my cp command at <http://heirloom.sourceforge.net>
> for quite some time, and I quickly decided to send files separated in
> some decently sized blocks. Otherwise if a whole file is sent at once
> and the source file is e.g. on an uncached floppy disk, cp will become
> uninterruptible for about a minute, which is a serious usability flaw.
> The user might discover that he is copying the wrong file, or he might
> simply change his mind and like to abort the copy or whatever. A
> performance gain of only 10 % is neglegible in comparison to this
> problem. Thus I think if copyfile() would not be interruptible by SIGINT
> and friends, its practical value would be quite limited.

Using a loop of 4k sendfile commands should be easy enough to do.
Problem is that copyfile(2) should do some decent cleanup after
receiving a signal.  Hans Reiser got it right that all filesystem
operations should be atomic.

Jörn

-- 
Premature optimization is the root of all evil.
-- Donald Knuth
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