Date: Wed, 25 Apr 2001 18:08:15 -0700 From: Dima Dorfman <dima@unixfreak.org> To: Garance A Drosihn <drosih@rpi.edu> Cc: "John W. De Boskey" <jwd@bsdwins.com>, "David O'Brien" <freebsd-current@FreeBSD.ORG>, Brian Somers <brian@Awfulhak.org> Subject: Re: Updated: cp -t patch (w/ commentary) Message-ID: <20010426010815.51F133E2A@bazooka.unixfreak.org> In-Reply-To: <p05100c03b70ca78af686@[128.113.24.47]>; from drosih@rpi.edu on "Wed, 25 Apr 2001 14:32:04 -0400"
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Garance A Drosihn <drosih@rpi.edu> writes:
> At 10:01 AM -0400 4/25/01, John W. De Boskey wrote:
> > I have reduced the runtime of the process so far by a solid
> >hour. My change to cp is the lowest level/minimal change fix
> >which allows me to maintain a O(1) time constraint. I've played
> >with (non-freebsd) versions of xargs already, and found them
> >(the various algorithms in xargs) to be more expensive than the
> >patch to cp.
>
> It is inconceivable that the proposed patch to 'xargs' would
> increase your running time. I don't mean the standard '-I'
> change, which would certainly destroy performance, but the
> proposed patch to 'xargs' which solves your specific problem
> in a general way.
>
> I'm still curious as to why you think the proposed change to
> xargs will cause you ANY performance problem. I simply can
> not imagine where you would get a performance problem from
> the -Y idea (though I'm still tempted to change the letter
> for that proposed option).
I think everything that should have been said in this thread already
has been (so I won't repeat it), except for the performace bit. As
the author of the patch, I doubt it would hinder performance. All it
does is move one part of a loop further down. Instead of doing
something once, it does part of that job twice. This job acts on
arguments *to xargs* (i.e., argv), and is nothing more than pointer
arithmetic and assignment. Unless you give umpteen arguments *to
xargs*, you shouldn't notice a difference in execution speed.
And as you (gad) said, implementing -I the way SUSv2 defines it would
most likely kill performance (most likely it'd also slow down whether
you actually use that option or not).
> Dimi has written one or two different patches to xargs. Did
^^^ <-- should be 'a', but that's okay. :-)
One patch.
Thanks,
Dima Dorfman
dima@unixfreak.org
P.S. obrien: that's a very clever and unintrusive way of avoiding
getting two copies of a message; much better than TrimYourCC@nuxi.com.
Those of us (well, at least me) who actually want a copy of the
message in our inbox greatly appreciate it. Thanks!
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