Date: Wed, 27 Oct 2004 14:00:31 -0400 From: John Baldwin <jhb@FreeBSD.org> To: freebsd-current@FreeBSD.org Cc: Mike Tancsa <mike@sentex.net> Subject: Re: device apic on a single processor machine Message-ID: <200410271400.31895.jhb@FreeBSD.org> In-Reply-To: <6.1.2.0.0.20041022113405.08fe2c48@64.7.153.2> References: <6.1.2.0.0.20041022113405.08fe2c48@64.7.153.2>
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On Friday 22 October 2004 11:40 am, Mike Tancsa wrote: > When moving from RELENG_4 to RELENG_5, I noticed that in GENERIC, the > options > > options SMP # Symmetric MultiProcessor Kernel > device apic # I/O APIC > > are enabled by default. Going forward, is this the best thing to leave in > my default kernel on a uniprocessor machine ? I am not using the ULE > scheduler either and have hyperthreading disabled in the BIOS. > > I did a search on google, and in 2003 it was said not to having either on a > single processor machine but its not clear if this is no longer the case. You do want to drop SMP. As far as 'apic', that is less clear. If you have lots of PCI devices that share interrupts for the !apic case and you do lots of interrupt intensive tasks, then 'device apic' might help. There may also be cases where it hurts. There have been reports that access to the apic registers for things like masking sources takes longer than on the 8259As. -- John Baldwin <jhb@FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve" = http://www.FreeBSD.org
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