From mboxrd@z Thu Jan 1 00:00:00 1970 From: Raymond Yau Subject: Re: [RFC] disabling ALSA period interrupts Date: Fri, 30 Apr 2010 07:18:08 +0800 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail-pz0-f202.google.com (mail-pz0-f202.google.com [209.85.222.202]) by alsa0.perex.cz (Postfix) with ESMTP id 1B17B24335 for ; Fri, 30 Apr 2010 01:18:09 +0200 (CEST) Received: by pzk40 with SMTP id 40so1455181pzk.23 for ; Thu, 29 Apr 2010 16:18:08 -0700 (PDT) In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: alsa-devel-bounces@alsa-project.org Errors-To: alsa-devel-bounces@alsa-project.org To: ALSA Development Mailing List List-Id: alsa-devel@alsa-project.org 2010/4/30 pl bossart > Howdy, > When PulseAudio is used and all PCM is routed through PulseAudio > (Fedora, Meego, etc), the notion of ALSA periods isn't very useful. > PulseAudio uses a timer to refill buffers and the period interrupts > are not used at all. > > So why not disable them entirely to reduce the number of wakeups? This > is possible with a number of existing DMA controllers. The simple > patch attached shows a proof-of-concept on HDAudio, it's been working > for 5 hours on my Fedora12 laptop without any glitches and powertop > does show _zero_ wakeups from the HDAudio controller (except on > startup). I am told by my colleagues working in Windows environments > that this is what's done on Vista/Windows7 btw. This isn't to say > Windows is great but that artificial generation of not-needed > interrupts is avoidable. > > There are probably some cases where you don't want this type of > behavior (broken hardware, legacy code with multiple-buffering, > disabled timer in PulseAudio), so I think it would make sense to > request the disabling of interrupts when hw_params are set, since this > is also the time when period sizes are set. I am aware that some > changes would be needed in pcm_lib.c, where all the error checks are > done. Takashi, Jaroslav, Lennart, what do you think? > Feedback and suggestions welcome. > Cheers > - Pierre > do you mean that it only work on HDaudio and not intel8x0 ? How about other drivers ? How pulseaudio and alsa driver resume/suspend from hibernation seem to be a mystery ?