on 05/04/2011 21:37 Matthias Andree said the following:
> Am 05.04.2011 15:51, schrieb Andriy Gapon:
> 
>> Boris,
>> ARC is an adaptive cache (as its name says), but the adaption doesn't happen
>> instantly.  So, when your applications do not use a lot of memory, but there 
>> is
>> steady filesystem usage, then ZFS ARC is going to gradually grow to consume 
>> an
>> optimum amount of RAM.  Then, your applications suddenly need a lot more 
>> memory,
>> they put pressure on VM system, ARC starts to shrink.  But if memory demand 
>> grows
>> faster than ARC shrinks, you are going to get a memory shortage.  And since 
>> you
>> don't have any swap to act as a safety net, you are getting out-of-memory 
>> situation.
>> So no surprises here, no system problems, just a normal foot-shooting :)
>>
>> Clamping maximum ARC size, as Jeremy has suggested, should help some.
>> Adding some swap would help a lot more.
> 
> The problem to me seems that ARC, the way you describe it, isn't really
> integrated with the system.

Define "really integrated".

> It's not buffer or cache memory, but some

True.

> separate application memory that can't adapt as quickly to system memory
> demands as all other kernel-managed caches and buffers can.

Other kernel-managed caches and buffers are not instant either.

But I have never compared "speed of adaptions".

-- 
Andriy Gapon
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