Hi, I am modifying the perf internals to avoid the overhead due to a second copy, when using Intel's BTS (execution tracing). Mainly, I have a buffer that fills during the execution of the traced process, and I sometimes need to save its contents.
When my buffer should be emptied, I schedule a task to copy the buffer contents to disk later. This action should be performed: - Whenether the buffer is full (in a IRQ handler). - Whenether the traced task is scheduled out. This is when it blocks. The problem is, deferring work in a work queue with schedule_work() during a context switch (in schedule()) leads to a deadlock, because both want to hold the same lock (&(&pool->lock)->rlock). I also tried to pre-schedule the task, make it wait_event_interruptible(), and wake_up() it during the context switch, but there is also a deadlock due to already-held &p->pi_lock in try_to_wake_up(). I am certainly doing something not the way it should be done. Is there a correct way to defer work during a context switch? Thanks! Adrien -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
