On Thu, 22 Feb 2007, Ingo Molnar wrote: > > * Davide Libenzi <davidel@xmailserver.org> wrote: > > > On Wed, 21 Feb 2007, Ingo Molnar wrote: > > > > > From: Ingo Molnar <[EMAIL PROTECTED]> > > > > > > add the move_user_context() method to move the user-space > > > context of one kernel thread to another kernel thread. > > > User-space might notice the changed TID, but execution, > > > stack and register contents (general purpose and FPU) are > > > still the same. > > > > Also signal handling should/must be maintained, on top of TID. You > > don't want the user to be presented with a different signal handling > > after an sys_async_exec call. > > right now CLONE_SIGNAL and CLONE_SIGHAND is used for new async threads, > so they should inherit and share all the signal settings.
Right. Sorry I missed the signal cloning flags (still has to go thru the whole code). > > So NTSK loads a non up2date FPUo, instead of the FPUc that was the > > "dirty" context to migrate (since TS_USEDFPU was set). I think you > > need an early __unlazy_fpu() in that case, that would turn the above > > into: > > yes. My plan is to to avoid all these problems by having a > special-purpose sched_yield_to(old_task, new_task) function. > > this, besides being even faster than the default scheduler (because the > runqueue balance does not change so no real scheduling decision has to > be done - the true scheduling decisions happen later on at async-wakeup > time), should also avoid all the FPU races: the FPU just gets flipped > between old_task and new_task (and TS_USEDFPU needs to be moved as well, > etc.). No intermediate task can come inbetween. > > can you see a hole in this sched_yield_to() method as well? Not sure till I see the code, but in that case we really need a sync©. This is really a fork-like for the FPU context IMO. The current "dirty" FPU context should follow both OTSK and NTSK. - Davide - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
