[patch] mallopt.3: Document M_ARENA_TEST, and M_ARENA_MAX.

[Carlos O'Donell]

On 08/30/2015 08:06 AM, Michael Kerrisk (man-pages) wrote:
> diff --git a/man3/mallopt.3 b/man3/mallopt.3
> index c09e801..fd41bf0 100644
> --- a/man3/mallopt.3
> +++ b/man3/mallopt.3
> @@ -66,8 +66,8 @@ and since glibc 2.15 by default.
>  In some versions of the allocator there was no limit on the number
>  of created arenas (e.g., CentOS 5, RHEL 5).
>  
> -When running programs on newer glibc versions,
> -these applications may exhibit high contention when accessing arenas.
> +When employing newer glibc versions, applications may in
> +some cases exhibit high contention when accessing arenas.

OK.

>  In these cases, it may be beneficial to increase
>  .B M_ARENA_MAX
>  to match the number of threads.
> @@ -79,7 +79,7 @@ This is the limit, in number of arenas created, at which the system
>  configuration will be examined to evaluate a hard limit on the
>  number of created arenas.
>  The computed limit is implementation-defined
> -and is usually a multiple of the number of available cores.
> +and is usually a multiple of the number of available CPUs.

I like this. This is better than what I wrote, since a core is not
the right unit here, we are reading /sys/devices/system/cpu/online,
or /proc/stat or /proc/cpuinfo to compute the number of online cpus.

>  Once the limit is computed, the result is final and constrains
>  the total number of arenas.
>  See
 
Thanks for the commit and fixup! 

Cheers,
Carlos.