Date: Wed, 25 May 2011 19:15:48 +0300 From: Andriy Gapon <avg@FreeBSD.org> To: Attilio Rao <attilio@FreeBSD.org> Cc: "freebsd-current@freebsd.org" <freebsd-current@FreeBSD.org>, "freebsd-arch@freebsd.org" <freebsd-arch@FreeBSD.org> Subject: Re: [rfc] remove hlt_cpus et al sysctls and related code Message-ID: <4DDD2B34.5070702@FreeBSD.org> In-Reply-To: <4DDA8B2A.6010500@FreeBSD.org> References: <4DD3F662.9040603@FreeBSD.org> <BANLkTikOTe9ut3GFx0bhOernKandRGLhPg@mail.gmail.com> <BANLkTinVGrLoAOS_ZQ1YVB_Fw1cvf5kHyA@mail.gmail.com> <BBCD9D8C-FCAF-4DE3-9F66-4B65AAABE67B@gmail.com> <BANLkTikMZ_xs4WCJVJG4oHe3rOKU8rqfVw@mail.gmail.com> <4DD54C18.8050305@FreeBSD.org> <4DDA8B2A.6010500@FreeBSD.org>
next in thread | previous in thread | raw e-mail | index | archive | help
on 23/05/2011 19:28 Andriy Gapon said the following: > I propose the following path for moving forward. > - use hint.lapic.X.disabled to disable individual CPUs by their APIC ID > - use machdep.hyperthreading_allowed tunable to disable second logical CPU on each > real core > > The above should already work as expected. One thing is that currently we have > handling of machdep.hyperthreading_allowed tunable under SCHED_ULE. I plan to > make it unconditional. > > Things to remove: > - all the related sysctls for dynamic onlining/offlining > - machdep.hlt_logical_cpus tunable (it duplicates hint.lapic.X.disabled) > > It's possible to keep machdep.hlt_logical_cpus and just add some code to convert > hlt_logical_cpus mask to a set of individual hint.lapic.X.disabled, but I don't > see very much value in that. But if there is a good reason to keep that tunable, > I am prepared to jump through this hoop. > > If no one objects to this proposal, I will provide a patch soon. The patch is here: http://people.freebsd.org/~avg/cpu-offline-sysctl.diff It should implement the strategy described above. I have mp_watchdog alone for now. It seems to have the same issues with respect to dynamic CPU state change. Besides its compilation is disabled when SCHED_ULE is enabled. mp_watchdog is a nice idea, but I wonder if anyone actually uses it (with success). -- Andriy Gapon
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?4DDD2B34.5070702>