From: Detlev Zundel Date: Fri, 22 Jan 2010 17:03:28 +0100 Subject: [U-Boot] Performance problems with gunzip In-Reply-To: <20100122154511.GA13051@morgana.gnudd.com> (Alessandro Rubini's message of "Fri, 22 Jan 2010 16:45:11 +0100") References: <000301ca9b6b$078572e0$@de> <000401ca9b73$3e5ff1e0$@de> <20100122154511.GA13051@morgana.gnudd.com> Message-ID: List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de Hi Alessandro, >> I fear this is not as easy as flipping a bit in a register. Depending >> on the platform caches tend to be tied to the MMU, so enabling the >> caches require setting up correct data structures for the MMU to work. >> That's the non-trivial work. > > Not that difficult, either. I never said it was difficult, only non-trivial :) > You just need to fill the top-level page table for 1MB sections (4096 > sections = 16k bytes, which must be aligned on a 16k boundary). > >> Apart from that, there is CONFIG_CMD_CACHE which builds >> common/cmd_cache.c. I see that at least two PXA250 platforms enable >> this, so maybe simply try that? > > I think it's always disabled on arm, for the mmu reason. > >> Maybe you can reap the code from their repository. If you do, please >> post it here ;) > > Or I can cook an RFC patch later, after redoing the 8815 patches. > I was just considering trying it these days, as I've done the same > on another straight-on-iron project and it's not that difficult. I am looking forward to something like this for a long time now and I'm sure other people will value it too, so thanks in advance! Detlev -- Sometimes I lie awake at night and I ask, "Why me?", then a voice answers "Nothing personal, your name just happened to come up." -- Charlie Brown -- DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: (+49)-8142-66989-40 Fax: (+49)-8142-66989-80 Email: dzu at denx.de