Messages in this thread Patch in this message | | | From | Rusty Russell <> | Subject | Re: [PATCH] 2.5.21 Nonlinear CPU support | Date | Wed, 12 Jun 2002 18:06:47 +1000 |
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In message <5.1.0.14.2.20020612084157.041970e0@pop.cus.cam.ac.uk> you write: > >Now, you *could* only allocate buffers for cpus where cpu_possible(i) > >is true, once the rest of the patch goes in. That would be a valid > >optimization. > > Please explain. What is cpu_possible()?
>From Hotcpu/hotcpu-boot-i386.patch.gz:
--- working-2.5.19-pre-hotcpu/include/asm-i386/smp.h Tue Jun 4 15:37:09 2002 +++ working-2.5.19-hotcpu/include/asm-i386/smp.h Mon Jun 3 18:00:09 2002 @@ -93,6 +94,8 @@ #define smp_processor_id() (current_thread_info()->cpu) #define cpu_online(cpu) (cpu_online_map & (1<<(cpu))) + +#define cpu_possible(cpu) (phys_cpu_present_map & (1<<(cpu))) extern inline unsigned int num_online_cpus(void) { ie. "Can this CPU number *ever* exist?", for exactly this kind of optimization. It looks like it was a mistake to leave that to a later patch, but I didn't appreciate the 64k-per-cpu buffer for NTFS (what is it for, by the way? per-cpu buffering for a filesystem seems, um, wierd).
Rusty. -- Anyone who quotes me in their sig is an idiot. -- Rusty Russell. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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