linux/kernel/sched_features.h, branch v2.6.27.59

sched: wakeup preempt when small overlap

2010-04-01T22:52:21Z

commit 15afe09bf496ae10c989e1a375a6b5da7bd3e16e upstream. Lin Ming reported a 10% OLTP regression against 2.6.27-rc4. The difference seems to come from different preemption agressiveness, which affects the cache footprint of the workload and its effective cache trashing. Aggresively preempt a task if its avg overlap is very small, this should avoid the task going to sleep and find it still running when we schedule back to it - saving a wakeup. Reported-by: Lin Ming Signed-off-by: Peter Zijlstra Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman

sched: disable the hrtick for now

2008-11-07T03:05:50Z

commit 0c4b83da58ec2e96ce9c44c211d6eac5f9dae478 upstream sched: disable the hrtick for now David Miller reported that hrtick update overhead has tripled the wakeup overhead on Sparc64. That is too much - disable the HRTICK feature for now by default, until a faster implementation is found. Reported-by: David Miller Acked-by: Peter Zijlstra Signed-off-by: Ingo Molnar Cc: Chuck Ebbert Signed-off-by: Greg Kroah-Hartman

sched: enable LB_BIAS by default

2008-08-21T06:18:02Z

Yanmin reported a significant regression on his 16-core machine due to: commit 93b75217df39e6d75889cc6f8050343286aff4a5 Author: Peter Zijlstra Date: Fri Jun 27 13:41:33 2008 +0200 Flip back to the old behaviour. Reported-by: "Zhang, Yanmin" Signed-off-by: Peter Zijlstra Signed-off-by: Ingo Molnar

sched: bias effective_load() error towards failing wake_affine().

2008-06-27T12:31:47Z

Measurement shows that the difference between cgroup:/ and cgroup:/foo wake_affine() results is that the latter succeeds significantly more. Therefore bias the calculations towards failing the test. Signed-off-by: Peter Zijlstra Cc: Srivatsa Vaddagiri Cc: Mike Galbraith Signed-off-by: Ingo Molnar

sched: update shares on wakeup

2008-06-27T12:31:45Z

We found that the affine wakeup code needs rather accurate load figures to be effective. The trouble is that updating the load figures is fairly expensive with group scheduling. Therefore ratelimit the updating. Signed-off-by: Peter Zijlstra Cc: Srivatsa Vaddagiri Cc: Mike Galbraith Signed-off-by: Ingo Molnar

sched: disable source/target_load bias

2008-06-27T12:31:44Z

The bias given by source/target_load functions can be very large, disable it by default to get faster convergence. Signed-off-by: Peter Zijlstra Cc: Srivatsa Vaddagiri Cc: Mike Galbraith Signed-off-by: Ingo Molnar

sched: fix calc_delta_asym()

2008-06-27T12:31:28Z

calc_delta_asym() is supposed to do the same as calc_delta_fair() except linearly shrink the result for negative nice processes - this causes them to have a smaller preemption threshold so that they are more easily preempted. The problem is that for task groups se->load.weight is the per cpu share of the actual task group weight; take that into account. Also provide a debug switch to disable the asymmetry (which I still don't like - but it does greatly benefit some workloads) This would explain the interactivity issues reported against group scheduling. Signed-off-by: Peter Zijlstra Cc: Srivatsa Vaddagiri Cc: Mike Galbraith Signed-off-by: Ingo Molnar

sched: revert the revert of: weight calculations

2008-06-27T12:31:27Z

Try again.. initial commit: 8f1bc385cfbab474db6c27b5af1e439614f3025c revert: f9305d4a0968201b2818dbed0dc8cb0d4ee7aeb3 Signed-off-by: Peter Zijlstra Cc: Srivatsa Vaddagiri Cc: Mike Galbraith Signed-off-by: Ingo Molnar

sched: trivial sched_features cleanup

2008-06-10T10:38:17Z

Remove unused debug/tuning features. Signed-off-by: Mike Galbraith Signed-off-by: Ingo Molnar

sched: /debug/sched_features

2008-04-19T17:45:00Z

provide a text based interface to the scheduler features; this saves the 'user' from setting bits using decimal arithmetic. Signed-off-by: Peter Zijlstra Signed-off-by: Ingo Molnar