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author | Lai Jiangshan <laijs@cn.fujitsu.com> | 2008-06-12 16:43:07 +0800 |
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committer | Ingo Molnar <mingo@elte.hu> | 2008-06-12 14:29:54 +0200 |
commit | 7a232e0350940d2664f4de5cc3f0f443bae5062d (patch) | |
tree | bb91a53faab7bf6e92df127f8bdb2225cf808925 /include | |
parent | 2e084786f6fe052274f1dfa7c675fe4a02cacd6e (diff) |
sched: 64-bit: fix arithmetics overflow
(overflow means weight >= 2^32 here, because inv_weigh = 2^32/weight)
A weight of a cfs_rq is the sum of weights of which entities
are queued on this cfs_rq, so it will overflow when there are
too many entities.
Although, overflow occurs very rarely, but it break fairness when
it occurs. 64-bits systems have more memory than 32-bit systems
and 64-bit systems can create more process usually, so overflow may
occur more frequently.
This patch guarantees fairness when overflow happens on 64-bit systems.
Thanks to the optimization of compiler, it changes nothing on 32-bit.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'include')
0 files changed, 0 insertions, 0 deletions