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由 Kirill Tkhai 提交于
Avoid double_rq_lock() and use TASK_ON_RQ_MIGRATING for load_balance(). The advantage is (obviously) not holding two rq->lock's at the same time and thereby increasing parallelism. Further note that if there was no task to migrate we will not have acquired the second rq->lock at all. The important point to note is that because we acquire dst->lock immediately after releasing src->lock the potential wait time of task_rq_lock() callers on TASK_ON_RQ_MIGRATING is not longer than it would have been in the double rq lock scenario. Signed-off-by: NKirill Tkhai <ktkhai@parallels.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Paul Turner <pjt@google.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Mike Galbraith <umgwanakikbuti@gmail.com> Cc: Kirill Tkhai <tkhai@yandex.ru> Cc: Tim Chen <tim.c.chen@linux.intel.com> Cc: Nicolas Pitre <nicolas.pitre@linaro.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/1408528109.23412.94.camel@tkhaiSigned-off-by: NIngo Molnar <mingo@kernel.org>
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