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Subject: Re: [PATCH] Linux-2.5 fix/improve get_pid()
From: Paul Larson <plars@austin.ibm.com>
To: Hubertus Franke <frankeh@us.ibm.com>
Cc: Andries Brouwer <aebr@win.tue.nl>, Andrew Morton <akpm@zip.com.au>,
       andrea@suse.de, Dave Jones <davej@suse.de>,
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On Thu, 2002-08-08 at 13:56, Hubertus Franke wrote:
> (a) Vanilla version which breaks down after 22K pids and 
> really sucks above 32.5K
> (b) Bill Irwin's, which keeps track of which PID is free and 
> which one is not ?
> (c) Andrea's patch which searches in the bitmap when we are 
> running out
> (d) Paul's patch, which I believe was based on one of my earlier 
> submission (03/02) that essentially switches between (a)+(c) at 
> the break even point.

> I feel (c) or (d) is a better solution over (a) and (b)...   Open for
> discussion.
> I have a test program that does the random pid deletion and pid allocation
> in user space. All what's required is to copy the get_pid() code from the
> kernel into there... Can make that available ...
> 
> I don't know what Paul has done to the patch since then ....

It's pretty much the same, with a couple of small changes.  After
forward porting your patch and the one from AA's patches (hch says that
one was actually done by Ihno Krumreich, thanks for the info), I added
the fix from (c) for the race, and moved the check for if(flags &
CLONE_IDLETASK) outside of get_pid into copy_process() since there's no
need to call get_pid and return just to find out that we need to use 0.

-Paul Larson

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