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Message-ID: <1fe6c7900901221921m586b129dwf8c3446f897b57f0@mail.gmail.com> Date: Thu, 22 Jan 2009 19:21:09 -0800 From: Mandeep Baines <msb@...gle.com> To: mingo@...e.hu, fweisbec@...il.com, linux-kernel@...r.kernel.org Cc: rientjes@...gle.com, mbligh@...gle.com, thockin@...gle.com Subject: Re: [PATCH v3] softlockup: remove hung_task_check_count On Thu, Jan 22, 2009 at 11:55 AM, Mandeep Singh Baines <msb@...gle.com> wrote: > > The unlock and lock could be removed and only compiled in if PREEMPT. > If the number of tasks isn't bound, the lock might be held too long. > This is incorrect. The adding the lock and unlock will not make the system more pre-emptive. To be more pre-emptive you'd want to check need_resched() as often as possible. > It would be kinda funny if hung_task caused a softlockup. > Again. This is incorrect. Rescheduling if need_resched() will prevent softlockup. Not sure what I was thinking this morning;) However, I am happy with the patch. To give writers a chance, the lock should held for bounded time. Holding the lock in khungtask (which is running at low scheduler priority) could potentially be delaying important work. The longer the lock is held, the bigger the priority inversion problem. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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