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

["Michael Kerrisk (man-pages)" <mtk dot manpages at gmail dot com>]

On 31 August 2015 at 15:20, Carlos O'Donell <carlos@redhat.com> wrote:
> 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!


Thanks for checking the changes, Carlos!

Cheers,

Michael




-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/