ZFS arc_reclaim_needed: better cooperation with pagedaemon

[Andriy Gapon]

on 12/09/2010 16:45 Martin Matuska said the following:
>  I am running a really busy system with 48GB of RAM, equipped with 300GB
> of SSD L2 cache as well and the I have recently observed the problem.
> The system runs static fileserving from ZFS via sendfile() and NFS export.
> 
> My vfs.zfs.arc_max is set to 40GB, vfs.zfs.arc_min is auto-set to 5GB (=
> metalimit / 2, metalimit = arc_max / 4)
> 
> NFS generates inactive memory that is not in use and leads to a
> reduction of ARC up to vfs.zfs.arc_min (not below).
> But I actually don't care about the cache of NFS and I really need the ARC.
> 
> So if I understand this correctly, this might help me - but it would
> lead to some kind of balance of incative memory vs ARC.
> Anyway, best help for me would probably be setting vfs.zfs.arc_min to a

Well, I am not sure - until you define a criterion "best" sounds a bit
subjective :-)
Anyway, I will greatly appreciate if you could test the patch before changing
arc_min.

> high value (20GB or more) so that the system tries to stay at this level.


-- 
Andriy Gapon