Il 15/07/2013 14:57, Jan Kiszka ha scritto: > On 2013-07-15 14:45, Paolo Bonzini wrote: >> Il 05/07/2013 19:51, Jan Kiszka ha scritto: >>> On 2013-07-05 14:39, Stefan Hajnoczi wrote: >>>> This series makes the following functions thread-safe: >>>> >>>> qemu_mod_timer_ns() >>>> qemu_mod_timer() >>>> qemu_del_timer() >>>> qemu_timer_pending() >>>> >>>> The following were already thread-safe: >>>> >>>> qemu_free_timer() >>>> qemu_new_timer() >>>> qemu_timer_expired() >>>> >>>> Now it is possible to use QEMUTimer outside the QEMU global mutex. Timer >>>> callbacks are still invoked from the main loop. If a thread wishes to run >>>> timer callbacks it must use a thread-safe QEMUBH (which Ping Fan Liu is >>>> working >>>> on). >>> >>> What do you mean with this? We need main-loop independent timers for any >>> task that depends on timely alarm delivery. Do your patches keep this in >>> mind as well? >> >> These are orthogonal issues. Stefan's usecase does not need timely >> delivery. > > Not necessarily. Timely delivery is likely the harder requirement that > also fulfills the need to move timer setup/manipulation outside of BQL. > I didn't have time to look into details yet, but there is a risk that > this rework will not help to achieve RT qualities
Not a risk, a certainty. :) > but rather needs another, non-orthogonal rework. If you consider the "timers as a library" approach from your presentation at last year's KVM Forum, this series does nothing to help that goal. But it also does nothing to hinder it (all it does is add a mutex, basically), which is why I said it is orthogonal. Paolo