From: Bodo Eggert <7eggert@gmx.de>
Subject: Re: fastboot: unpacking initramfs faster
To: Andreas Robinson <andr345@gmail.com>,
       Arjan van de Ven <arjan@infradead.org>, linux-kernel@vger.kernel.org
Reply-To: 7eggert@gmx.de
Date: Tue, 24 Mar 2009 23:11:56 +0100
References: <cj9yI-540-17@gated-at.bofh.it>
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Andreas Robinson <andr345@gmail.com> wrote:

> I tried running the initramfs unpacking asynchronously (and earlier) but
> ran into a curious problem: The parent thread stalled until
> decompression was done. I don't know why - I made sure that the two
> threads ran on different cores. Perhaps the parent was cache starved.

I could not stall my system by gzip</dev/urandom>/dev/null.
Maybe you accidentally used vfork?

> I then looked at multithreaded decompression and found that neither gzip
> files nor deflate streams provide enough information (eg block lengths)
> to let you share the decompression among threads.
> 
> It can be done of course, but obviously not without modifying file
> formats and userspace tools.
> 
> (Thoughts of snowballs and hell presented themselves at this point.)

Why not make a new set? http://7eggert.dyndns.org:8080/l/bgz.tar.gz

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