Date: Thu, 19 May 2011 19:58:00 +0300 From: Andriy Gapon <avg@FreeBSD.org> To: Attilio Rao <attilio@FreeBSD.org>, Garrett Cooper <yanegomi@gmail.com> 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: <4DD54C18.8050305@FreeBSD.org> In-Reply-To: <BANLkTikMZ_xs4WCJVJG4oHe3rOKU8rqfVw@mail.gmail.com> 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>
next in thread | previous in thread | raw e-mail | index | archive | help
on 18/05/2011 20:04 Attilio Rao said the following: > 2011/5/18 Garrett Cooper <yanegomi@gmail.com>: >> We use this internally at work still with a software config that uses 4BSD so >> as long as there is an equivalent tunable, that's good enough for us moving >> forward. Can you please clarify which exactly tunable(s) do you use/need? Just turning hyperthreading on/off or more? (BTW, doing that via BIOS is inconvenient / not feasible?) BTW, I think that if we switch hyperthreading off then we better off not sending Start IPI to the logical CPUs at all. > Tunables are pretty much acceptable for this case. What is really broken is the > on-the-fly ability to mark CPUs active/inactive and subsequent handovers. Yes, I completely agree. Static disabling of CPUs doesn't have any problems, and IMO, currently the best way to do it is with hint.lapic.X.disabled. > I thought Andriy attached a patch to the tree, but it doesn't seem so... > anyway, yes, I think that adding tunables for this is very reasonable and not > as dangerous as the current mechanism. I agree. I haven't sent a patch, because I don't have it yet :) I decided to solicit opinions before getting to hacking code. -- Andriy Gapon
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?4DD54C18.8050305>