6bfd6d72f5
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>
34 lines
680 B
C
34 lines
680 B
C
#ifndef _LINUX_CPUDL_H
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#define _LINUX_CPUDL_H
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#include <linux/sched.h>
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#define IDX_INVALID -1
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struct array_item {
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u64 dl;
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int cpu;
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};
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struct cpudl {
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raw_spinlock_t lock;
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int size;
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int cpu_to_idx[NR_CPUS];
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struct array_item elements[NR_CPUS];
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cpumask_var_t free_cpus;
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};
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#ifdef CONFIG_SMP
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int cpudl_find(struct cpudl *cp, struct task_struct *p,
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struct cpumask *later_mask);
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void cpudl_set(struct cpudl *cp, int cpu, u64 dl, int is_valid);
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int cpudl_init(struct cpudl *cp);
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void cpudl_cleanup(struct cpudl *cp);
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#else
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#define cpudl_set(cp, cpu, dl) do { } while (0)
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#define cpudl_init() do { } while (0)
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#endif /* CONFIG_SMP */
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#endif /* _LINUX_CPUDL_H */
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