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Re: [Qemu-devel] GSoC 2017 Proposal: TCG performance enhancements
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] GSoC 2017 Proposal: TCG performance enhancements |
Date: |
Mon, 27 Mar 2017 13:32:37 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.7.0 |
On 25/03/2017 17:52, Pranith Kumar wrote:
> * Implement an LRU translation block code cache.
>
> In the current TCG design, when the translation cache fills up, we flush all
> the translated blocks (TBs) to free up space. We can improve this situation
> by not flushing the TBs that were recently used i.e., by implementing an LRU
> policy for freeing the blocks. This should avoid the re-translation overhead
> for frequently used blocks and improve performance.
IIRC, Emilio measured one flush every roughly 10 seconds with 128 MB
cache in system emulation mode---and "never" is a pretty accurate
estimate for user-mode emulation. This means that a really hot block
would be retranslated very quickly.
Paolo