linux-kernel - Re: fastboot: unpacking initramfs faster

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Message-Id: <E1LmEqj-0001SN-6Y@be1.7eggert.dyndns.org>
Date:	Tue, 24 Mar 2009 23:11:56 +0100
From:	Bodo Eggert <7eggert@....de>
To:	Andreas Robinson <andr345@...il.com>,
	Arjan van de Ven <arjan@...radead.org>,
	linux-kernel@...r.kernel.org
Subject: Re: fastboot: unpacking initramfs faster

Andreas Robinson <andr345@...il.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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