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Re: [PATCH 1/3] percpu: Add alloc_percpu_aligned()

From Christopher Lameter <cl@linux.com>
Newsgroups linux.kernel
Subject Re: [PATCH 1/3] percpu: Add alloc_percpu_aligned()
Date 2017-08-02 16:00 +0200
Message-ID <ua2lQ-281-13@gated-at.bofh.it> (permalink)
References <u9XFv-7As-5@gated-at.bofh.it> <u9XFw-7As-25@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On Wed, 2 Aug 2017, Huang, Ying wrote:

> --- a/include/linux/percpu.h
> +++ b/include/linux/percpu.h
> @@ -129,5 +129,8 @@ extern phys_addr_t per_cpu_ptr_to_phys(void *addr);
>  #define alloc_percpu(type)						\
>  	(typeof(type) __percpu *)__alloc_percpu(sizeof(type),		\
>  						__alignof__(type))
> +#define alloc_percpu_aligned(type)					\
> +	((typeof(type) __percpu *)__alloc_percpu(sizeof(type),		\
> +		max_t(unsigned int, cache_line_size(), __alignof__(type))))
>
>  #endif /* __LINUX_PERCPU_H */

This is not needeed since alloc_percpu() already uses __alignof__(type).

If you add an attribute to the definition of "type" that requires
cacheline alignmet (f.e. __cacheline_aligned) then alloc_percpu() will
align the allocation as you desire.

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Thread

[PATCH 1/3] percpu: Add alloc_percpu_aligned() "Huang, Ying" <ying.huang@intel.com> - 2017-08-02 11:00 +0200
  Re: [PATCH 1/3] percpu: Add alloc_percpu_aligned() Christopher Lameter <cl@linux.com> - 2017-08-02 16:00 +0200
    Re: [PATCH 1/3] percpu: Add alloc_percpu_aligned() "Huang\, Ying" <ying.huang@intel.com> - 2017-08-03 02:40 +0200

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