[Xen-devel] Re: lmbench lat_mmap slowdown with CONFIG_PARAVIRT

[Ingo Molnar <mingo@xxxxxxx>]

* Jeremy Fitzhardinge <jeremy@xxxxxxxx> wrote:

>>> Also, I just posted patches to get rid of all pvops calls when 
>>> fetching or setting flags in a pte, which I hope will help.
>>
>> Sounds like it will help.
>
> ...but apparently not.

ping?

This is a very serious paravirt_ops slowdown affecting the native kernel's 
performance to the tune of 5-10% in certain workloads.

It's been about 2 years ago that paravirt_ops went upstream, when you told 
us that something like this would never happen, that paravirt_ops is 
designed so flexibly that it will never hinder the native kernel - and if 
it does it will be easy to fix it. Now is the time to fulfill that 
promise.

        Ingo

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