From: =?utf-8?B?SsO2cm4=?= Engel Subject: Re: [patch 4/15] fs/logfs/compr.c Date: Fri, 11 Apr 2008 12:41:28 +0200 Message-ID: <20080411104128.GG25462@logfs.org> References: <20080401181308.512473173@logfs.org> <20080401181332.853833004@logfs.org> <200804101613.48465.arnd@arndb.de> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mtd@lists.infradead.org To: Arnd Bergmann Return-path: Content-Disposition: inline In-Reply-To: <200804101613.48465.arnd@arndb.de> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Thu, 10 April 2008 16:13:47 +0200, Arnd Bergmann wrote: >=20 > 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? >=20 > 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. J=C3=B6rn --=20 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