lkml.org 
[lkml]   [2003]   [Sep]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] Many groups patch.
On Mon, Sep 29, 2003 at 06:29:32PM -0400, Pete Zaitcev wrote:
> >> This version drops the internal groups array (it's so often shared
> >> that it's not worth it, and the logic becomes a bit neater), and does
> >> vmalloc fallback in case someone has massive number of groups.
> >
> > Why?
>
> > The vmalloc space is limited, and the code just gets uglier.
>
> Tim was going to write a version that segments groups into
> smaller arrays. I reckon it was too difficult?

I posted it once or twice then got busy. It's an array of pages. Rusty has
it, but didn't believe me when I said Linus wouldn't let vmalloc() fly.

> > Have you been looking at glibc sources lately, or why do you believe that
> > we should encourage insane usage?
>
> We have some customers who run insane number of groups,
> with their own patches. This practice is popular in the
> Beowulf crowd for some reason. I should note this is not
> very mainstream.

I'd be ok with the simplest "kmalloc or too bad" version, but our customers
wouldn't.

My version uses a struct group_info which has an array of pages. The groups
are sorted and bsearched, instead of linear. The perfomance is quite good.
An older version against 2.6.0-test1 or something is attached. If this
method will fly, I'll take some of Rusty's good ideas and finish this
version of it..

Linus?
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:49    [W:0.045 / U:0.168 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site