Date: Fri, 17 Dec 2010 22:06:12 +0800 From: David Xu <davidxu@freebsd.org> To: John Baldwin <jhb@freebsd.org> Cc: arch@freebsd.org, Sergey Babkin <babkin@verizon.net> Subject: Re: Realtime thread priorities Message-ID: <4D0B6E54.2070802@freebsd.org> In-Reply-To: <201012170752.06540.jhb@freebsd.org> References: <201012101050.45214.jhb@freebsd.org> <201012160940.58116.jhb@freebsd.org> <4D0AC3EC.1040701@freebsd.org> <201012170752.06540.jhb@freebsd.org>
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John Baldwin wrote: > Yes, we do not do priority lending for sleep locks, and to date we never > have. This is not a new problem and moving RT priority higher is not > introducing any _new_ problems. However, it does bring _new_ functionality > that some people need. Just because you don't need it doesn't mean it isn't > important. > > Don't let the perfect be the enemy of the good. > > I guess that your real requirement is preempting at user boundary for static priority thread, however current code does not. I doubt that preempting in kernel path which holding an unknown lock has any visible benefit for your application. Yes, perfect is not the enemy but the goal, isn't mutex with priority propagating for perfect ?
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