Date: Wed, 06 Jun 2012 23:16:09 +0300 From: Andriy Gapon <avg@FreeBSD.org> To: Mitsuru IWASAKI <iwasaki@jp.FreeBSD.org> Cc: attilio@FreeBSD.org, freebsd-acpi@FreeBSD.org, freebsd-arch@FreeBSD.org Subject: Re: cpu stopping Message-ID: <4FCFBA89.9030105@FreeBSD.org> In-Reply-To: <20120607.040342.73368798.iwasaki@jp.FreeBSD.org> References: <4FCB0FE5.4050607@FreeBSD.org> <20120603.234243.28389486.iwasaki@jp.FreeBSD.org> <4FCBBEDD.5000604@FreeBSD.org> <20120607.040342.73368798.iwasaki@jp.FreeBSD.org>
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on 06/06/2012 22:03 Mitsuru IWASAKI said the following: > Hi, > > I've created the patches of experimental implementation based on > discussion so far. > > http://people.freebsd.org/~iwasaki/acpi/cpustop_hook-20120606.diff > > In acpi_wakeup.c, cpususpend_handler() and susppcbs are replaced with > cpustop_handler() and stoppcbs. > > This is for RELENG_9 and only for i386 but I think it's enough for the > start. I think that there is no need for DPCPU here. All (affected) CPUs should see the same hook, IMO. At least I can not imagine the case where something else would be required. Also, it might make sense to provide a void pointer as a potential context for for the context. As Attilio has said before this has many similarities to what smp_rendezvous does, just for different kind of situations. > From: Andriy Gapon <avg@FreeBSD.org> > Subject: Re: cpu stopping > Date: Sun, 03 Jun 2012 22:45:33 +0300 > Message-ID: <4FCBBEDD.5000604@FreeBSD.org> > >>> Never mind :) What I'm trying to do in the patches is just to unify >>> amd64/i386 independent part (acpi_wakeup.c) for the code maintenance, >>> so please let's commit it first, then start re-design the >>> cpususpend_handler(). >> >> In no way I am trying to delay your work :) >> Just shared my view on the design of cpu stopping code. > > I got it :) > >>>> My view of how this should work is: >>>> - there can be only one master CPU that controls all other (slave) CPUs >>>> - the master sets entry and exit hooks >>> >>> Entry hook for suspending might be >>> ---- >>> ctx_fpusave(suspfpusave[cpu]); >>> wbinvd(); >>> CPU_SET_ATOMIC(cpu, &stopped_cpus); >>> ---- >>> >>> and for stopping is >>> ---- >>> /* Indicate that we are stopped */ >>> CPU_SET_ATOMIC(cpu, &stopped_cpus); >>> ---- >>> >>> Correct? >> >> Yes. The only nit is that CPU_SET_ATOMIC(cpu, &stopped_cpus) could be part of >> the wait loop prologue. No need to duplicate it in each hook. > > OK, I did so. > > I hope the patch is not far from your idea. > > Thanks! -- Andriy Gapon
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