Still getting kmem exhausted panic

Ben Kelly ben at
Tue Sep 28 16:24:48 UTC 2010

On Sep 28, 2010, at 9:36 AM, Andriy Gapon wrote:
> Well, no time for me to dig through all that history.
> arc_max should be a hard limit and it is now. If it ever wasn't then it was a bug.

I believe the size of the arc could exceed the limit if your working set was larger than arc_max.  The arc can't (couldn't then, anyway) evict data that is still referenced.

A contributing factor at the time was that the page daemon did not take into account back pressure from the arc when deciding which pages to move from active to inactive, etc.  So data was more likely to be referenced and therefore forced to remain in the arc.

I'm not sure if this is still the current state.  I seem to remember some changesets mentioning arc back pressure at some point, but I don't know the details.

- Ben

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