Re: [Qemu-devel] [PATCH 0/3] target-arm: cache tbflags in CPUARMState

[Alex Bennée]

Paolo Bonzini <address@hidden> writes:

> On 10/11/2016 12:42, Alex Bennée wrote:
>>
>> Paolo Bonzini <address@hidden> writes:
>>
>>> Computing TranslationBlock flags is pretty expensive on ARM, especially
>>> 32-bit.  Because tbflags are computed on every tb lookup, it is not
>>> unlikely to see cpu_get_tb_cpu_state close to the top of the profile
>>> now that QHT makes the hash table much more efficient.
>>>
>>> However, most tbflags only change when the EL is switched or after
>>> MSR instructions.  Based on this observation, this series caches these
>>> tbflags in CPUARMState, resulting in a 10-15% speedup on 32-bit code.
>>
>> Hi,
>>
>> I'm starting to clear out my review queue but I notice these now longer
>> apply cleanly to master. Where you going to re-issue the series once
>> you'd addressed Peter's concerns?
>
> Yes, I didn't want to send them two days before soft freeze and Peter's
> vacation. :)

Cool. Well I'll happily look at it while he's away as I think I need to
learn more about the flag mechanism anyway. Unless there are any
regressions that have come up during soft-freeze that I need to look at?

--
Alex Bennée