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* sched/deadline: Switch CPU's presence test orderJuri Lelli2014-02-271-2/+2
| | | | | | | | | | | | | | | Commit 82b9580 ("sched/deadline: Test for CPU's presence explicitly") changed how we check if a CPU returned by cpudeadline machinery is valid. But, we don't want to call cpu_present() if best_cpu is equal to -1. So, switch the order of tests inside WARN_ON(). Signed-off-by: Juri Lelli <juri.lelli@gmail.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: boris.ostrovsky@oracle.com Cc: konrad.wilk@oracle.com Cc: rostedt@goodmis.org Link: http://lkml.kernel.org/r/1393238832-9100-1-git-send-email-juri.lelli@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* sched/deadline: Test for CPU's presence explicitlyBoris Ostrovsky2014-02-211-3/+3
| | | | | | | | | | | | | | | | | | A hot-removed CPU may have ID that is numerically larger than the number of existing CPUs in the system (e.g. we can unplug CPU 4 from a system that has CPUs 0, 1 and 4). Thus the WARN_ONs should check whether the CPU in question is currently present, not whether its ID value is less than num_present_cpus(). Cc: Ingo Molnar <mingo@kernel.org> Cc: Juri Lelli <juri.lelli@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> Reported-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1392646353-1874-1-git-send-email-boris.ostrovsky@oracle.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* sched/deadline: Fix sparse static warningsFengguang Wu2014-01-161-3/+3
| | | | | | | | | | | | | | | | new sparse warnings: >> kernel/sched/cpudeadline.c:38:6: sparse: symbol 'cpudl_exchange' was not declared. Should it be static? >> kernel/sched/cpudeadline.c:46:6: sparse: symbol 'cpudl_heapify' was not declared. Should it be static? >> kernel/sched/cpudeadline.c:71:6: sparse: symbol 'cpudl_change_key' was not declared. Should it be static? >> kernel/sched/cpudeadline.c:195:15: sparse: memset with byte count of 163928 Signed-off-by: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: Juri Lelli <juri.lelli@gmail.com> Fixes: 6bfd6d72f51c ("sched/deadline: speed up SCHED_DEADLINE pushes with a push-heap") Link: http://lkml.kernel.org/r/52d47f8c.EYJsA5+mELPBk4t6\%fengguang.wu@intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* sched/deadline: speed up SCHED_DEADLINE pushes with a push-heapJuri Lelli2014-01-131-0/+216
Data from tests confirmed that the original active load balancing logic didn't scale neither in the number of CPU nor in the number of tasks (as sched_rt does). Here we provide a global data structure to keep track of deadlines of the running tasks in the system. The structure is composed by a bitmask showing the free CPUs and a max-heap, needed when the system is heavily loaded. The implementation and concurrent access scheme are kept simple by design. However, our measurements show that we can compete with sched_rt on large multi-CPUs machines [1]. Only the push path is addressed, the extension to use this structure also for pull decisions is straightforward. However, we are currently evaluating different (in order to decrease/avoid contention) data structures to solve possibly both problems. We are also going to re-run tests considering recent changes inside cpupri [2]. [1] http://retis.sssup.it/~jlelli/papers/Ospert11Lelli.pdf [2] http://www.spinics.net/lists/linux-rt-users/msg06778.html Signed-off-by: Juri Lelli <juri.lelli@gmail.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1383831828-15501-14-git-send-email-juri.lelli@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
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