diff options
| -rw-r--r-- | rts/Schedule.c | 32 |
1 files changed, 25 insertions, 7 deletions
diff --git a/rts/Schedule.c b/rts/Schedule.c index abf3be58af..3eb9624231 100644 --- a/rts/Schedule.c +++ b/rts/Schedule.c @@ -699,7 +699,8 @@ schedulePushWork(Capability *cap USED_IF_THREADS, #if defined(THREADED_RTS) Capability *free_caps[n_capabilities], *cap0; - nat i, n_free_caps; + nat i, n_wanted_caps, n_free_caps; + StgTSO *t; // migration can be turned off with +RTS -qm if (!RtsFlags.ParFlags.migrate) return; @@ -713,8 +714,22 @@ schedulePushWork(Capability *cap USED_IF_THREADS, sparkPoolSizeCap(cap) < 1) return; } - // First grab as many free Capabilities as we can. - for (i=0, n_free_caps=0; i < n_capabilities; i++) { + // Figure out how many capabilities we want to wake up. We need at least + // sparkPoolSize(cap) plus the number of spare threads we have. + t = cap->run_queue_hd; + n_wanted_caps = sparkPoolSizeCap(cap); + if (t != END_TSO_QUEUE) { + do { + t = t->_link; + if (t == END_TSO_QUEUE) break; + n_wanted_caps++; + } while (n_wanted_caps < n_capabilities-1); + } + + // Grab free capabilities, starting from cap->no+1. + for (i = (cap->no + 1) % n_capabilities, n_free_caps=0; + n_free_caps < n_wanted_caps && i != cap->no; + i = (i + 1) % n_capabilities) { cap0 = capabilities[i]; if (cap != cap0 && !cap0->disabled && tryGrabCapability(cap0,task)) { if (!emptyRunQueue(cap0) @@ -824,10 +839,13 @@ schedulePushWork(Capability *cap USED_IF_THREADS, // release the capabilities for (i = 0; i < n_free_caps; i++) { task->cap = free_caps[i]; - // The idea behind waking up the capability unconditionally is that - // it might be able to steal sparks. Perhaps we should only do this - // if there were sparks to steal? - releaseAndWakeupCapability(free_caps[i]); + if (sparkPoolSizeCap(cap) > 0) { + // If we have sparks to steal, wake up a worker on the + // capability, even if it has no threads to run. + releaseAndWakeupCapability(free_caps[i]); + } else { + releaseCapability(free_caps[i]); + } } } task->cap = cap; // reset to point to our Capability. |