On Thu, 29.04.10 17:38, pl bossart (bossart.nospam at gmail.com) wrote: > 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. This patch looks very interesting and desirable. This is something have long been waiting for. I wonder how this actually relates to snd_pcm_sw_params_set_period_event() though. > 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? I am sold! Lennart -- Lennart Poettering Red Hat, Inc. lennart [at] poettering [dot] net http://0pointer.net/lennart/ GnuPG 0x1A015CC4
