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    SubjectRe: [PATCH 2/2] x86: modify show_shared_cpu_map in intel_cacheinfo
    Bert Wesarg wrote:
    > On Fri, Mar 28, 2008 at 7:19 PM, Mike Travis <travis@sgi.com> wrote:
    >> > Aren't the most cpumaps (like cpu/cpu*/topology/*_siblings or
    >> > node/node*/cpumap) bitmasks?
    >>
    >> I did an informal survey and you are right, the majority of references do use
    >> cpumask_scnprintf instead of cpulist_scnprintf. Maybe the later function was
    >> added later?
    >>
    >> To me though, it would seem that:
    >>
    >> 240-255
    >>
    >> is more readable than:
    >>
    >> 00000000,00000000,00000000,00000000,00000000,00000000,00000000,0000ffff
    >>
    >> And as I mentioned, bitmask_parselist() [libbitmask(3)] does parse the output.
    > But libbitmask has a bitmask_parsehex() too. (but thanks for the
    > pointer to this code).
    >
    > Anyway, your above example is wrong, the most significant bits comes first:
    >
    > ffff0000,00000000,00000000,00000000,00000000,00000000,00000000,00000000
    >
    > This makes it not more readable, but I think readability isn't in this
    > case of that much importance.

    The original problem was how to avoid allocating a large stack space to display
    cpu ids. By using cpulist_scnprintf, it accomplishes this without, what I think
    is too much pain. If it's really that much of a problem, I will rework this patch.
    But the length of the line with 4096 cpus will be 1152 bytes Is this really
    better?

    >
    > I further think, this problem could be easily solved, if NR_CPUS and
    > possibly your nr_cpus_ids is somehow exported to user space.
    >
    > With this information, the user is not surprised to see more that 1024
    > bits (=CPU_SETSIZE, which is currently the glibc constant for the
    > sched_{set,get}affinity() API). Also the glibc has the new variable
    > cpu_set_t size API (since 2.7).

    Yes, thanks. That is being dealt with in another task.

    Thanks,
    Mike


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