From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paul Barton-Davis Date: Wed, 27 Oct 1999 17:55:58 +0000 Subject: Re: sequencer timing issues Message-Id: List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-sound@vger.kernel.org [ why softwerk can't use a kernel sequencer ] >Hmm..sounds like you're already paying much of the price of the >hyperseq approach..might as well go all the way. :) thats the plan, just as soon as i: * finish autoconf-izing Quasimodo * fix Quasimodo's audio input system * finish writing a prototype of my take on the plugin API * port the ALSA CS4231 driver to pcm-v2 * port SoftWerk to Gtk-- etc. etc. :) >> in SoftWerk's case, because it doesn't process audio data in any way, >> I use sigitimer(2) to give me a periodic async signal every so often >> (typically 20-100ms: its controllable in the UI). i use this to >> measure the passage of time, and compute when a beat/tick is >> happening. soon, i will use the RTC with select(2), which will be >> more accurate and permit much faster tempos than sigitimer can. > >Wouldn't you say that an HZ > 100 kernel is the cleanest solution? its the cleanest, but not the best. HZ = 1000 adds about 8% overhead to IRQ processing *all the time*. and even then, the system timer is only accurate to 1ms, which is still not adequate for some envisioned uses of SoftWerk (though given its use of h/w MIDI ports and the speed of MIDI communication, its pretty excellent for 99% of them :) --p