Re: [PATCH 1/2] kvm: use modern cpumask primitives, no cpumask_ton stack
From: Avi Kivity
Date: Sun Dec 07 2008 - 11:14:20 EST
Avi Kivity wrote:
Rusty Russell wrote:
We're getting rid on on-stack cpumasks for large NR_CPUS.
1) Use cpumask_var_t and alloc_cpumask_var (a noop normally). Fallback
code is inefficient but never happens in practice.
Wow, code duplication from Rusty. Things must be bad.
Since we're in a get_cpu() here, how about a per_cpu static cpumask
instead? I don't mind the inefficient fallback, just the duplication.
Btw, for the general case, instead of forcing everyone to duplicate, how
about:
cpumask_var_t cpus;
with_cpumask(cpus) {
... code to populate cpus
smp_call_function_some(...);
} end_with_cpumask(cpus);
Where with_cpumask() allocates cpus, and uses a mutex + static fallback
on failure.
May need a couple of variants (spinlock + GFP_NOWAIT, mutex with
sleeping allocation).
--
error compiling committee.c: too many arguments to function
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