* Paolo Bonzini ([email protected]) wrote:
> This patch adds to the model an optimization, whereby threads are
> told whether they are still being waited on, and skip the futex wakeup
> if not.
Merged, thanks!
Mathieu
> ---
> futex-wakeup/futex.spin | 40 +++++++++++++++++++++++++++++++---------
> 1 files changed, 31 insertions(+), 9 deletions(-)
>
> diff --git a/futex-wakeup/futex.spin b/futex-wakeup/futex.spin
> index ab41a0a..44acd7e 100644
> --- a/futex-wakeup/futex.spin
> +++ b/futex-wakeup/futex.spin
> @@ -9,9 +9,12 @@
> * Waker
> * while (1) {
> * this.queue = gp;
> - * if (gp_futex == -1) {
> - * gp_futex = 0;
> - * futex_wake = 1;
> + * if (this.waiting == 1) {
> + * this.waiting = 0;
> + * if (gp_futex == -1) {
> + * gp_futex = 0;
> + * futex_wake = 1;
> + * }
> * }
> * }
> *
> @@ -19,6 +22,7 @@
> * in_registry = 1;
> * while (1) {
> * gp_futex = -1;
> + * waiting |= (queue != gp);
> * in_registry &= (queue != gp);
> * if (all in_registry == 0) {
> * progress:
> @@ -56,6 +60,7 @@
> #define get_pid() (_pid)
>
> int queue[2] = 0;
> +int waiting[2] = 0;
> int futex_wake = 0;
> int gp_futex = 0;
> int gp = 1;
> @@ -69,14 +74,18 @@ active [2] proctype waker()
> :: 1 ->
> queue[get_pid()] = gp;
>
> - if
> - :: (gp_futex == -1) ->
> - gp_futex = 0;
> + if
> + :: (waiting[get_pid()] == 1) ->
> + waiting[get_pid()] = 0;
> + if
> + :: (gp_futex == -1) ->
> + gp_futex = 0;
> #ifndef INJ_QUEUE_NO_WAKE
> - futex_wake = 1;
> + futex_wake = 1;
> #endif
> - :: else ->
> - skip;
> + :: else ->
> + skip;
> + fi;
> fi;
> od;
> }
> @@ -92,6 +101,18 @@ restart:
> #ifndef INJ_LATE_DEC
> gp_futex = -1;
> #endif
> + if
> + :: (in_registry[0] == 1 && queue[0] != gp) ->
> + waiting[0] = 1;
> + :: else ->
> + skip;
> + fi;
> + if
> + :: (in_registry[1] == 1 && queue[1] != gp) ->
> + waiting[1] = 1;
> + :: else ->
> + skip;
> + fi;
>
> if
> :: (in_registry[0] == 1 && queue[0] == gp) ->
> @@ -105,6 +126,7 @@ restart:
> :: else ->
> skip;
> fi;
> +
> if
> :: (in_registry[0] == 0 && in_registry[1] == 0) ->
> progress:
> --
> 1.7.6
>
>
>
> _______________________________________________
> ltt-dev mailing list
> [email protected]
> http://lists.casi.polymtl.ca/cgi-bin/mailman/listinfo/ltt-dev
>
--
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com
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