Observations from a ZFS reorganization on 12-STABLE

[Pete French]

On 17/03/2019 21:57, Eugene Grosbein wrote:
> I agree. Recently I've found kind-of-workaround for this problem:
> increase vm.v_free_min so when "FREE" memory goes low,
> page daemon wakes earlier and shrinks UMA (and ZFS ARC too) moving some 
> memory
> from WIRED to FREE quick enough so it can be re-used before bad things 
> happen.
> 
> But avoid increasing vm.v_free_min too much (e.g. over 1/4 of total RAM)
> because kernel may start behaving strange. For 16Gb system it should be 
> enough
> to raise vm.v_free_min upto 262144 (1GB) or 131072 (512M).
> 
> This is not permanent solution in any way but it really helps.

Ah, thats very interesting, thankyou for that! I;ve been bitten by this 
issue too in the past, and it is (as mentioned) much improved on 12, but 
the act it could still cause issues worries me.

-pete.