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From: Florian Weimer <fweimer@redhat.com>
To: "H.J. Lu" <hjl.tools@gmail.com>
Cc: GNU C Library <libc-alpha@sourceware.org>
Subject: Re: RFC: Add getcpu wrapper
References: <CAMe9rOpcy16tREX8Gb0qYPXXc__Vzykj2c=M20aBOn4p0gUBGw@mail.gmail.com>
	<87pnuggf5z.fsf@oldenburg2.str.redhat.com>
	<CAMe9rOqEeSY7H-MQybk=wuR4aK4juTNj5dGK1CvjYkxExYOAuw@mail.gmail.com>
Date: Wed, 05 Dec 2018 16:48:43 +0100
In-Reply-To: <CAMe9rOqEeSY7H-MQybk=wuR4aK4juTNj5dGK1CvjYkxExYOAuw@mail.gmail.com>
	(H. J. Lu's message of "Wed, 5 Dec 2018 07:40:12 -0800")
Message-ID: <87lg54gejo.fsf@oldenburg2.str.redhat.com>
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* H. J. Lu:

> On Wed, Dec 5, 2018 at 7:35 AM Florian Weimer <fweimer@redhat.com> wrote:
>>
>> * H. J. Lu:
>>
>> > returns such info.  But syscall () is too slow.  I'd like to add a wrapper to
>> > glibc.   Any comments?
>>
>> We already have it as sched_getcpu, I think.
>>
>
> We have
>
> int
> sched_getcpu (void)
> {
> #ifdef __NR_getcpu
>   unsigned int cpu;
>   int r = INLINE_VSYSCALL (getcpu, 3, &cpu, NULL, NULL);
>
>   ^^^^^  I need the node info.
>
>   return r == -1 ? r : cpu;
> #else
>   __set_errno (ENOSYS);
>   return -1;
> #endif
> }

Ah, so you want to pass a non-null second argument to getcpu?

I think we can expose getcpu (with two arguments), under that name.  Add
it to <sched.h> or <unistd.h>; I do not have a strong preference.

Thanks,
Florian