Re: [patch 4/15] fs/logfs/compr.c

From: JÃrn Engel
Date: Fri Apr 11 2008 - 06:41:46 EST


On Thu, 10 April 2008 16:13:47 +0200, Arnd Bergmann wrote:
>
> How much time is spent in the compression code? Would it be helpful
> to have a percpu stream and do preempt_disable around it instead
> of the mutex?
>
> That would improve parallelism and cache-locality of the compression,
> at the cost of adding a source of latency to preemptible kernels.

Several years back (before logfs) I was planning to do just that. It
turned out that ipsec doesn't work in such a fashion, because each
connection is a stream. And the two block-oriented users, jffs2 and
cramfs just weren't worth it.

Might be a good idea by now. I guess it should become self-contained
code, so that jffs2, cramfs and ubifs can use it as well.

JÃrn

--
Write programs that do one thing and do it well. Write programs to work
together. Write programs to handle text streams, because that is a
universal interface.
-- Doug MacIlroy
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