Messages in this thread |  | | Date | Wed, 16 Jan 2013 13:02:51 +0100 | Subject | Re: [PATCH] tty: Only wakeup the line discipline idle queue when queue is active | From | Ivo Sieben <> |
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2013/1/16 Preeti U Murthy <preeti@linux.vnet.ibm.com>: > > Yes.Thank you very much for the explanation :) But I dont see how the > context switching goes away with your patch.With your patch, when the > higher priority thread comes in when the lower priority thread is > running in the critical section,it will see the wait queue empty and > "continue its execution" without now wanting to enter the critical > section.So this means it will preempt the lower priority thread because > it is not waiting on a lock anyway.There is a context switch here right? > I dont see any problem in scheduling due to this,but I do think your > patch is essential. >
I don't have a problem that there is a context switch to the high priority process: it has a higher priority, so it probably is more important. My problem is that even when the waitqueue is empty, the high priority thread has a risk to block on the spinlock needlessly (causing context switches to low priority task and back to the high priority task)
Regards, Ivo Sieben
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