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From: Florian Weimer <fw@deneb.enyo.de>
To: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Cc: libc-alpha@sourceware.org
Subject: Re: [PATCH 6/7] linux: Refactor sched_getcpu in terms of getcpu
References: <20191129210327.26434-1-adhemerval.zanella@linaro.org>
	<20191129210327.26434-6-adhemerval.zanella@linaro.org>
Date: Sun, 01 Dec 2019 14:22:00 -0000
In-Reply-To: <20191129210327.26434-6-adhemerval.zanella@linaro.org>
	(Adhemerval Zanella's message of "Fri, 29 Nov 2019 18:03:26 -0300")
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* Adhemerval Zanella:

> diff --git a/sysdeps/unix/sysv/linux/sched_getcpu.c b/sysdeps/unix/sysv/linux/sched_getcpu.c
> index 65dd9fdda7..3646c8b713 100644
> --- a/sysdeps/unix/sysv/linux/sched_getcpu.c
> +++ b/sysdeps/unix/sysv/linux/sched_getcpu.c
> @@ -17,23 +17,11 @@
>  
>  #include <errno.h>
>  #include <sched.h>
> -#include <sysdep.h>
> -
> -#ifdef HAVE_GETCPU_VSYSCALL
> -# define HAVE_VSYSCALL
> -#endif
> -#include <sysdep-vdso.h>
>  
>  int
>  sched_getcpu (void)
>  {
> -#ifdef __NR_getcpu
>    unsigned int cpu;
> -  int r = INLINE_VSYSCALL (getcpu, 3, &cpu, NULL, NULL);
> -
> +  int r = __getcpu (&cpu, NULL);
>    return r == -1 ? r : cpu;
> -#else
> -  __set_errno (ENOSYS);
> -  return -1;
> -#endif
>  }

I wonder if the current state is a useful performance optimization.