Emmanuel, hi folks, i'm not sure if i read the patch correctly, but i'd really would like to see the setcontext()/swapcontext() to not use a system call. IIRC its using the system call to set the signal masks etc. Can't this mask be kept in userland only and inspected by the kernel on a signal? Would this make libpthread also a lot faster? since it doesn't need a system call too? Can this info be stored in a uncacheable page shared with all CPU cores so no IPI's need to be done either? Maybe together with other data that needs to be synchronised anyway?
One of the reasons this is important to me is the excessive use of setcontext()/swapcontext() in NetBSD/usermode. It would be nice if it really gets down on system calls. Talking on NetBSD/usermode, i'd really love someone to have a look/audit on its use of setcontext()/swapcontext() since i know it has some shortcuts that might be illegal / uncaring. I do get weird panics at time on a setcontext that are most likely caused by these shortcuts. With regards, Reinoud
