From mboxrd@z Thu Jan 1 00:00:00 1970 From: Juri Lelli Subject: Re: [RFD/RFC PATCH 5/8] sched: Add proxy execution Date: Thu, 11 Oct 2018 15:42:24 +0200 Message-ID: <20181011134224.GT9130@localhost.localdomain> References: <20181009092434.26221-1-juri.lelli@redhat.com> <20181009092434.26221-6-juri.lelli@redhat.com> <20181010131048.54afd1b6@luca64> <20181011123448.GS9130@localhost.localdomain> <20181011125325.GA9867@hirez.programming.kicks-ass.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: luca abeni , mingo@redhat.com, rostedt@goodmis.org, tglx@linutronix.de, linux-kernel@vger.kernel.org, claudio@evidence.eu.com, tommaso.cucinotta@santannapisa.it, alessio.balsini@gmail.com, bristot@redhat.com, will.deacon@arm.com, andrea.parri@amarulasolutions.com, dietmar.eggemann@arm.com, patrick.bellasi@arm.com, henrik@austad.us, linux-rt-users@vger.kernel.org To: Peter Zijlstra Return-path: Content-Disposition: inline In-Reply-To: <20181011125325.GA9867@hirez.programming.kicks-ass.net> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-rt-users.vger.kernel.org On 11/10/18 14:53, Peter Zijlstra wrote: [...] > I think it was the safe and simple choice; note that we're not migrating > just a single @p, but a whole chain of @p. rq->curr must not be any of the > possible @p's. rq->idle, is per definition not one of the @p's. > > Does that make sense? It does, and I guess is most probably the safest choice indeed. But, just to put together a proper comment for next version.. The chain we are migrating is composed of blocked_task(s), so tasks that blocked on a mutex owned by @p. Now, if such a chain has been built, it means that proxy() has been called "for" @p previously, and @p might be curr while one of its waiters might be proxy. So, none of the blocked_ task(s) should be rq->curr (even if one of their scheduling context might be in use)?