From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Korsgaard Subject: Re: Performance of spi_mpc83xx.c sucks. Date: Tue, 02 Dec 2008 17:23:42 +0100 Message-ID: <87d4gav94h.fsf@macbook.be.48ers.dk> References: <1224605947.14078.17.camel@gentoo-jocke.transmode.se> <877i81rf2g.fsf@macbook.be.48ers.dk> <002f01c933ab$4bee9180$e3cbb480$@Tjernlund@transmode.se> <200811202010.30845.david-b@pacbell.net> <1228231118.9867.108.camel@gentoo-jocke.transmode.se> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: David Brownell , spi-devel-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org To: joakim.tjernlund-SNLAxHN9vbcOP4wsBPIw7w@public.gmane.org Return-path: In-Reply-To: <1228231118.9867.108.camel-/EMGr9iCeazgSi9v3i4K4Pmbkio/vSLMs0AfqQuZ5sE@public.gmane.org> (Joakim Tjernlund's message of "Tue\, 02 Dec 2008 16\:18\:38 +0100") List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: spi-devel-general-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: linux-spi.vger.kernel.org >>>>> "Joakim" == Joakim Tjernlund writes: Hi, >> So long as you do the polling with IRQs enabled, I'd keep it >> simple and just always poll. YMMV of course, but most devices >> seem to prefer more like 10 MHz clocks than 1 MHz ones. Joakim> Sorry for the delay, forgot about this. Joakim> Won't polling for long periods starve user space? How to Joakim> overcome this? I guess it won't be any worse than the processor being overloaded with interrupts - In fact it's better, as there's more real work done. Joakim> Why use a kernel thread(mpc83xx_spi.0) to do the work? Would Joakim> it not be better if the polling was in process context? I guess that's needed for the async stuff. -- Bye, Peter Korsgaard ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/