Re: [gentoo-user] Is my system (really) using nptl

[Florian Philipp]

Am 14.10.2012 17:07, schrieb Michael Mol:
> On Sun, Oct 14, 2012 at 5:31 AM, Florian Philipp <lists@×××××××××××.net> wrote:
>> Am 14.10.2012 01:20, schrieb Michael Mol:
>>> On Sat, Oct 13, 2012 at 4:18 PM, Canek Peláez Valdés <caneko@×××××.com> wrote:
>>>> On Sat, Oct 13, 2012 at 2:50 PM, Michael Mol <mikemol@×××××.com> wrote:
>>>> [snip]
>>>>> (Well, I'm not certain that POSIX thinks of threads as parents to each other.
>>>>
>>>> Hence the reason I put "parent" in quotes, and I specified "actually,
>>>> the thread that created it".
>>>>
>>>>> There are *numerous* IPC mechanisms available on Linux. For starters,
>>>>> there are sockets (domain, IPv4, IPv6, et al), named pipes, signals,
>>>>> mmap()'d files, messaging, etc.
>>>>
>>>> Yeah, none of them "easy and quickly" to use, or at least not if you
>>>> compare it with shared memory.
>>>
>>> I assume you mean 'shared memory' in the 'many threads to an address
>>> space', not the /dev/shm sense.
>>>
>>
>> If we really want to be nit-picking, we have to assume 'shared memory'
>> as in malloc'ed [1] or stack memory. Anonymous mmap'ed memory mappings
>> are preserved across forks and changes in them can be shared since
>> kernel 2.4.
>
> Absolutely.
>
>> [1] Yes, I know that malloc uses mmap but its mappings are MAP_PRIVATE.
>
> For the GNU libc, yeah. I noticed that in strace, and was amused.
>

Huh? Are there other libcs that do it differently? I can't imagine any
alternative (except of the sbrk function from the bad old days).

Regards,
Florian Philipp