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Re: [RFC] Don't lookup full CPU state in the indirect branch fast path o
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From: |
Richard Henderson |
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Subject: |
Re: [RFC] Don't lookup full CPU state in the indirect branch fast path on AArch64 when running in user mode. |
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Date: |
Mon, 19 Oct 2020 15:58:36 -0700 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 |
On 10/19/20 3:44 PM, Owen Anderson wrote:
> My use case is currently using QEMU 4.0, but we will be moving to QEMU
> 4.2 soon. I do not have --enable-tcg-debug enabled.
> e979972a6a1 does look promising, and like it might deliver increased
> performance for our use case. It looks like the code in 4.0 is doing a
> lot more work gathering the flags values from a variety of places.
Yes, before 4.2, we did a *lot* more work gathering flags, and the overhead you
see roughly corresponds with what I saw.
r~