On Thu, Aug 11, 2016 at 02:53:10AM -0400, Robin Humble wrote:
have you tried setting zfs_arc_min = zfs_arc_max? that should stop ARC from releasing memory for linux buffers to use.
is that what most folks do?
no idea. it just seems like something that's worth trying.
as the SSD is fast at large reads (500MB/s), I could also just cache metadata and not data. would that make sense do you think?
it might help. I used to do it and it didn't seem to do much, but that was on a low memory system with only 1GB of ARC. IIRC, I have primarycache=metadata and secondarycache=all you can set that per filesystem or zvol for both ARC and L2ARC with 'zfs set'. primarycache=all | none | metadata Controls what is cached in the primary cache (ARC). If this property is set to all, then both user data and metadata is cached. If this property is set to none, then neither user data nor metadata is cached. If this property is set to metadata, then only metadata is cached. The default value is all. secondarycache=all | none | metadata Controls what is cached in the secondary cache (L2ARC). If this property is set to all, then both user data and metadata is cached. If this property is set to none, then neither user data nor metadata is cached. If this property is set to metadata, then only metadata is cached. The default value is all. craig -- craig sanders <cas@taz.net.au>