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SubjectRe: [PATCH 06/10] x86: reduce memory and stack usage in intel_cacheinfo

* H. Peter Anvin <hpa@zytor.com> wrote:

> Ingo Molnar wrote:
>>> The main goal was to avoid allocating 4096 bytes when only 32 would do
>>> (characters needed to represent nr_cpu_ids cpus instead of NR_CPUS cpus.)
>>> But I'll look at cleaning it up a bit more. It wouldn't have to be a
>>> function if CHUNKSZ in cpumask_scnprintf() were visible (or a
>>> non-changeable constant.)
>>
>> well, do we care about allocating 4096 bytes, as long as we also free it?
>> It's not like we need to clear all the bytes or something. Am i missing
>> something here?
>
> Well, 32 bytes fits on the stack, whereas 4096 bytes requires
> allocating a page -- which means either taking the risk of failing or
> blocking. Of course, we're doing this for output, which has the same
> issue.

hm, i thought this was all implemented via dynamic allocation already,
within the cpumask_scnprintf function. But i see it doesnt do it - i
guess a new call could be introduced, cpumask_scnprintf_ptr() which
passes in a cpumask pointer and does dynamic allocation itself?

Ingo


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