Re: [PATCH] shrinker support for the mmu cache

[Avi Kivity <avi@qumranet.com>]

Marcelo Tosatti wrote:
>>
>> While aging is not too hard to do, I don't think it would add much in 
>> practice; we rarely observe mmu shadow pages being recycled due to 
>> memory pressure.  So this is mostly helpful for preventing a VM from 
>> pinning memory when under severe memory pressure, where we don't expect 
>> good performance anyway.
>>     
>
> Issue is that the shrinker callback will not be called only under
> severe memory pressure, but for normal system pressure too.
>
>   

How much shrinkage goes on under normal pressure?

Rebuilding a single shadow page costs a maximum of 512 faults (so about 
1 msec).  If the shrinker evicts one entry per second, this is a 
performance hiy of 0.1%.

Perhaps if we set the cost high enough, the normal eviction rate will be 
low enough.

-- 
error compiling committee.c: too many arguments to function


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