Re: [RFC PATCH] getcpu_cache system call: caching current CPU number (x86)

[Mathieu Desnoyers <mathieu.desnoyers-vg+e7yoeK/dWk0Htik3J/w@public.gmane.org>]

----- On Jul 17, 2015, at 6:58 AM, Ondřej Bílka neleai@seznam.cz wrote:
[...]
>> If we invoke this per-thread registration directly in the glibc NPTL
>> implementation,
>> in start_thread, do you think it would fit your requirements ?
>>
> A generic solution would be adding eager initialization of thread_local
> variables which would fix more performance problems.

Concretely, what code would be in charge of this initialization ?

What changes does "eager initialization" imply from the current
implementation ?

> Second would be write patch to libc adding function
> pthread_create_add_hook_np to register function that would be ran after
> each thread creation.

Do you suggest that this callback should be registered once per thread,
or somehow attached to pthread_attr_t ? As maintainer of lttng-ust,
where we need some control over our own threads, but where we want minimal
impact on the overall application, I would really prefer if we can attach
the callback to pthread_attr_t.

Thanks,

Mathieu


-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com