Date: Fri, 3 Jul 2009 11:10:16 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Paul Menage <menage@google.com>
Cc: Benjamin Blum <bblum@google.com>, lizf@cn.fujitzu.com, serue@us.ibm.com,
       containers@lists.linux-foundation.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] Adds a read-only "procs" file similar to "tasks"
 that  shows only unique tgids
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On Fri, 3 Jul 2009 10:54:48 -0700 Paul Menage <menage@google.com> wrote:

> >__Unfortunately radix-trees are presented as operating on
> > void* data, so one would need to do some typecasting when storing
> > BITS_PER_LONG-sized bitfields inside them.
> 
> That would mean adding something a bit like the IDA wrapper that
> converts IDR to deal with bitfields?

I guess so.

> Is the benefit of avoiding a vmalloc() at all costs really worth the
> additional complexity

Well no.  But nor was it worth the additional complexity the last twenty
times someone resorted to vmalloc to solve a problem of this nature.  Taking
a kernel-wide perspective here gives a different answer.

However I don't think a little scoreboarding thing (what's the correct
term) built around radix-trees would suffice to solve many of those
past sins.  Whereas a general dynamic array thing would be applicable
in many cases.
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