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Re: [Qemu-devel] [RFC 26/38] cpu: protect tb_jmp_cache with seqlock
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From: |
Paolo Bonzini |
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Subject: |
Re: [Qemu-devel] [RFC 26/38] cpu: protect tb_jmp_cache with seqlock |
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Date: |
Fri, 4 Sep 2015 12:04:33 +0200 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.1.0 |
On 04/09/2015 10:50, Paolo Bonzini wrote:
> Having now reviewed the patch, I think we can do better.
>
> The idea is:
>
> - only the CPU thread can set cpu->tb_jmp_cache[]
>
> - other threads can, under seqlock protection, _clear_ cpu->tb_jmp_cache[]
>
> - the seqlock can be protected by tb_lock. Then you need not retry the
> read, you can just fall back to the slow path, which will take the
> tb_lock and thus serialize with the clearer.
... and then we're back to the idea of making tb_invalidated_flag per-TB. :)
Paolo