Re: [tip:timers/core] timer: Allocate per-cpu tvec_base's statically

[Eric Dumazet]

On Thu, 2015-04-02 at 11:47 -0700, tip-bot for Peter Zijlstra wrote:
> Commit-ID:  b337a9380f7effd60d082569dd7e0b97a7549730
> Gitweb:     http://git.kernel.org/tip/b337a9380f7effd60d082569dd7e0b97a7549730
> Author:     Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> AuthorDate: Tue, 31 Mar 2015 20:49:00 +0530
> Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
> CommitDate: Thu, 2 Apr 2015 17:46:00 +0200
> 
> timer: Allocate per-cpu tvec_base's statically
> 
...

> This will also guarantee that tvec_base is cacheline aligned. Even
> though tvec_base has ____cacheline_aligned stuck on, kzalloc_node() does
> not actually respect that (but guarantees a minimum u64 alignment).

...

> +static DEFINE_PER_CPU(struct tvec_base, __tvec_bases);


This should probably use DEFINE_PER_CPU_ALIGNED() to avoid holes in
percpu section.


$ objdump -h kernel/time/built-in.o | grep percpu
111 .data..percpu 00002592  0000000000000000  0000000000000000  0001cbc0
2**6


instead of :

$ objdump -h kernel/time/built-in.o | grep percpu
111 .data..percpu 00000532  0000000000000000  0000000000000000  0001cbc0
2**5
113 .data..percpu..shared_aligned 00002040  0000000000000000
0000000000000000  0001d140  2**6

I'll send a patch.


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