Date: Fri, 18 Mar 2011 18:15:24 +0200 From: Kostik Belousov <kostikbel@gmail.com> To: Andriy Gapon <avg@freebsd.org> Cc: freebsd-hackers@freebsd.org, Jung-uk Kim <jkim@freebsd.org>, Bruce Evans <brde@optusnet.com.au>, Maxim Dounin <mdounin@mdounin.ru> Subject: Re: get_cyclecount(9) deprecation Message-ID: <20110318161524.GC78089@deviant.kiev.zoral.com.ua> In-Reply-To: <4D837F7F.2060403@freebsd.org> References: <201103171436.22283.jkim@FreeBSD.org> <20110318162252.S984@besplex.bde.org> <20110318135647.GY78089@deviant.kiev.zoral.com.ua> <4D837F7F.2060403@freebsd.org>
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--gL219CPYpMREpKpt Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Mar 18, 2011 at 05:51:27PM +0200, Andriy Gapon wrote: > on 18/03/2011 15:56 Kostik Belousov said the following: > > On Fri, Mar 18, 2011 at 05:26:53PM +1100, Bruce Evans wrote: > > ... > >> - set cputicker() has some design bugs. It assumes that the tick freq= uency > >> is the same across all CPUs, but the TSC is per-CPU. I have an old = SMP > >> system with CPUs of different frequency that can demonstrate bugs fr= om > >> this. > > We definitely do not support configurations with different models of > > CPUs in SMP, this is what Simmetric is about. Different as in frequency > > or stepping. >=20 > Are there any fundamental reasons for us to not support that configuratio= n in > situations where hardware and BIOS (in x86 case) happen to support it? >=20 > I am personally more interested in non-uniform topologies like one packag= e having > two cores and another having four. We do not handle CPU errata/quirks individually per-core. I think that we assume that all cores have the same stepping and thus require the same workarounds, if any, as BSP. Also, I think tsc calibration is done only on BSP, but I may be wrong there. --gL219CPYpMREpKpt Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (FreeBSD) iEYEARECAAYFAk2DhRwACgkQC3+MBN1Mb4jtmACguqAsvWYeXb6Y23NHLqnblNiC UMEAoIu/L8aaw1tE+X5gnCw0Ir3euF7i =QS5W -----END PGP SIGNATURE----- --gL219CPYpMREpKpt--
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