From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from n9a.bullet.ukl.yahoo.com ([217.146.183.157]) by www.linuxtv.org with smtp (Exim 4.63) (envelope-from ) id 1JmXya-0003MZ-DN for linux-dvb@linuxtv.org; Thu, 17 Apr 2008 19:32:49 +0200 Message-ID: <48076C7A.7070901@yahoo.de> Date: Thu, 17 Apr 2008 17:27:54 +0200 From: Robert Schedel MIME-Version: 1.0 To: linux-dvb@linuxtv.org References: <47F9E95D.6070705@yahoo.de> <200804120100.14568@orion.escape-edv.de> <48066F62.8000709@yahoo.de> In-Reply-To: <48066F62.8000709@yahoo.de> Subject: Re: [linux-dvb] High CPU load in "top" due to budget_av slot polling List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: linux-dvb-bounces@linuxtv.org Errors-To: linux-dvb-bounces+mchehab=infradead.org@linuxtv.org List-ID: Robert Schedel wrote: > Is the 250ms timeout an approved limit? Decreasing it would push the > load further down. Probably it still has to cover slow CAMs as well as a > stressed PCI bus. Unfortunately, without CAM/CI I cannot make any > statements myself. Just got another idea to improve the code: Function "saa7146_wait_for_debi_done_sleep" could be reworked to use what is known as "truncated binary exponential backoff" algorithm. IOW, on each sleep duplicate the period from 1ms until a fixed maximum, e.g. 32ms. This way polling ends fast for those users with fast bus/CAM, and those requiring 200ms due to slow bus/CAM should not worry about e.g. 216ms response time. My first tests look promising (load goes down to 0). However, is not the simple BEB algorithm already patented? Regards, Robert _______________________________________________ linux-dvb mailing list linux-dvb@linuxtv.org http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb