[LAD] Faster context switch

Hi list, I am seeing what appears to be a 4 - 7 usec context switch time on a 3 GHz Core 2 Duo machine with the 2.6 kernel, and 10 - 15 usecs on a 1.66 GHz Atom. Is that reasonable? Does anyone have any tips on how to speed that up, if possible? The background is that I have two apps --- one a straight Linux app and the other a Wine one. The Linux app is doing the mixing and the Wine app is hosting Windows VSTs. During audio processing I use a sem_t to signal from the mixer app to the vst app. Once the vst app is done processing, it signals back to the mixer app over another sem_t. I believe this is roughly the approach taken by other linux audio apps to host Wine vsts. And is also something like how Jack does IPC. But it takes about 4-7 usecs on the faster machine to signal another app and have it wake up again. I assume this is the time needed for a context switch. Since this has to happen twice per buffer, at a 32 sample buffer size and with 10 VSTs, overhead accounts for about 14% of the CPU. On the slower Atom machine, it would account for 33% of the CPU. Any hints on how to reduce that time, or an alternate IPC design to look in to? Thanks for any help, Michael Ost Muse Research, Inc.