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

[Ingo Molnar <mingo@elte.hu>]

* 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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