Casey Marshall wrote: > On Jan 31, 2006, at 6:10 PM, David P Grove wrote: > >> Jikes RVM also does m-to-n threading, so it's there's more than 1 VM >> that's whacky in this regard. The things we need to do are most likely >> different than what Kaffe needs to do, but having a chance to inject >> a VM >> callback before the thread dives off into a blocking system call is >> something we would like to be able to do. We have some linux specific >> hacks (evil with dlopen to intercept poll, select, etc), but it's >> fragile >> and doesn't work on other platforms like AIX and OS X that Jikes RVM >> runs >> on. >> > > Would my suggestion for Enter/Exit callbacks help this? > > Though enter/exit callbacks may help for a few syscalls but it won't for some (like blocking read/write). For these new calls you need handle blocking queues in the VM thread scheduler. That needs to put the fd into non-blocking mode and when you do a read you first check if there is any data (in non-blocking mode) and if there is not data then the thread system queues the current thread and tells the scheduler to jump somewhere else until some datas are available on the specified fd. So we must really stick to rerouting a few IOs. I am sure that handling m-to-n threading system is as difficult as what we are doing (maybe more). Regards, Guilhem.
