Re: ps performance sucks (was Re: dcache_rcu [performance results])

Erik Andersen
2002-11-05T06:06:53Z

On Mon Nov 04, 2002 at 09:44:07PM -0800, Martin J. Bligh wrote:
> > Hehe. You just reinvented my old /dev/ps driver. :)
>
> Indeed, sounds much more like a /dev thing than a /proc thing
> at this point ;-)
>
> > http://www.busybox.net/cgi-bin/cvsweb/busybox/examples/kernel-patches/devps.patch.9_25_2000?rev=1.2&content-type=text/vnd.viewcvs-markup
> >
> > This is what Linus has to say on the subject:
> >
> > ... If the problem is that /proc
> > is too large, then the right solution is to just clean up
> > /proc. Which is getting done. And yes, /proc will be larger
> > than /dev/ps, but I still find that preferable to having two
> > incompatible ways to do the same thing.
>
> Ummm ... how do we make /proc smaller than 1 file to open per PID?
> It's pretty easy to get it down that far. But it still sucks.
>
> > I do dislike /dev/ps mightily.
>
> Well it can't be any worse than the current crap. At least it'd
> stand a chance in hell of scaling a little bit. So I took a very
> quick look ... what syscalls are you reduced to per pid, one ioctl
> and one read?

As I implemented it, it was one ioctl per pid... Of course
it could be easily modified to be one syscall, one read from
the /dev/ps char device, or similar...

-Erik

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Erik B. Andersen http://codepoet-consulting.com/
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