On Thu April 5 2007 6:04 pm, Benjamin Herrenschmidt wrote: > On Thu, 2007-04-05 at 14:55 -0500, Kevin Corry wrote: > > First, the stock 2.6.20 kernel has a prototype in include/linux/smp.h for > > a function called smp_call_function_single(). However, this routine is > > only implemented on i386, x86_64, ia64, and mips. Perfmon2 apparently > > needs to call this to run a function on a specific CPU. Powerpc provides > > an smp_call_function() routine to run a function on all active CPUs, so I > > used that as a basis to add an smp_call_function_single() routine. I've > > included the patch below and was wondering if it looked like a sane > > approach. > > We should do better... it will require some backend work for the various > supported PICs though. I've always wanted to look into doing a > smp_call_function_cpumask in fact :-)
I was actually wondering about that myself today. It would seem like an smp_call_function() that takes a CPU mask would be much more flexible than either the current version or the new one that I proposed. However, that was a little more hacking that I was willing to do today on powerpc architecture code. :) > > Next, we ran into a problem related to Perfmon2 initialization and sysfs. > > The problem turned out to be that the powerpc version of topology_init() > > is defined as an __initcall() routine, but Perfmon2's initialization is > > done as a subsys_initcall() routine. Thus, Perfmon2 tries to initialize > > its sysfs information before some of the powerpc cpu information has been > > initialized. However, on all other architectures, topology_init() is > > defined as a subsys_initcall() routine, so this problem was not seen on > > any other platforms. Changing the powerpc version of topology_init() to a > > subsys_initcall() seems to have fixed the bug. However, I'm not sure if > > that is going to cause problems elsewhere in the powerpc code. I've > > included the patch below (after the smp-call-function-single patch). Does > > anyone know if this change is safe, or if there was a specific reason > > that topology_init() was left as an __initcall() on powerpc? > > It would make sense to follow what other archs do. Note that if both > perfmon and topology_init are subsys_initcall, that is on the same > level, it's still a bit hairy to expect one to be called before the > other... I wondered that as well, but based on what Arnd posted earlier (presumably about the kernel linking order), the topology_init() call, which is in the arch/ top-level directory, should occur before pfm_init(), which is in perfmon/, even if both are in the same initcall level. Thanks, -- Kevin Corry [EMAIL PROTECTED] http://www.ibm.com/linux/ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/