From mboxrd@z Thu Jan 1 00:00:00 1970 From: Benno Senoner Date: Thu, 26 Aug 1999 20:42:29 +0000 Subject: Re: Bad MIDI performance : 10ms latency instead of the expected 1-1.5ms 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 On Thu, 26 Aug 1999, Jaroslav Kysela wrote: >> > A 100% CPU usage for 1sec ? > > I can't believe this. > > Try it. > > linux/drivers/sound/mpu401.c: > > /* > * Sometimes it takes about 30000 loops before the output becomes ready > * (After reset). Normally it takes just about 10 loops. > */ > > for (timeout = 30000; timeout > 0 && !output_ready(devc); timeout--); arrgh, really bad ! > > 200bytes/sec is just rudiculous , how do you plan to drive an external synth > > with that little MIDI bandwidth ? > > I need a timer around 2000Hz for some good code. I won't support polling > mode (busy loop) in any case. Yes, is there some free timer available in Linux to perform this job ? It would be nice to be able to use the full MIDI bandwidth without eating all the CPU power. > > > Many songs uses up much of the 3000 bytes/sec bandwidth, especially > > when there are many controller/pitchbend events present. > > > > Do you know if the RX FIFO of the MPU401 has the same problem (no interrupt) or > > is there an interrupt present ? > > No, MPU401 has Rx interrupt. Fortunately ! , this means you can still use your PC as a realtime synth/sampler when played through a MIDI masterkeyboard > > > Does this mean that sequencers running under Windows have the same problems > > as we in Linux on the AWE64 ? > > I don't know, how is this problem solved under W$. > > Jaroslav certainly in a sub-optimal way. :-) regards, Benno.