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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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e210bffd39
The task_fork_fair() callback already calls __set_task_cpu() and takes rq->lock. If we move the sched_class::task_fork callback in sched_fork() under the existing p->pi_lock, right after its set_task_cpu() call, we can avoid doing two such calls and omit the IRQ disabling on the rq->lock. Change to __set_task_cpu() to skip the migration bits, this is a new task, not a migration. Similarly, make wake_up_new_task() use __set_task_cpu() for the same reason, the task hasn't actually migrated as it hasn't ever ran. This cures the problem of calling migrate_task_rq_fair(), which does remove_entity_from_load_avg() on tasks that have never been added to the load avg to begin with. This bug would result in transiently messed up load_avg values, averaged out after a few dozen milliseconds. This is probably the reason why this bug was not found for such a long time. Reported-by: Vincent Guittot <vincent.guittot@linaro.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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| .. | ||
| auto_group.c | ||
| auto_group.h | ||
| clock.c | ||
| completion.c | ||
| core.c | ||
| cpuacct.c | ||
| cpuacct.h | ||
| cpudeadline.c | ||
| cpudeadline.h | ||
| cpufreq_schedutil.c | ||
| cpufreq.c | ||
| cpupri.c | ||
| cpupri.h | ||
| cputime.c | ||
| deadline.c | ||
| debug.c | ||
| fair.c | ||
| features.h | ||
| idle_task.c | ||
| idle.c | ||
| loadavg.c | ||
| Makefile | ||
| rt.c | ||
| sched.h | ||
| stats.c | ||
| stats.h | ||
| stop_task.c | ||
| swait.c | ||
| wait.c | ||