On Sun, Nov 28, 2010 at 11:41:35PM -0600, Stan Hoeppner wrote: > Yclept Nemo put forth on 11/28/2010 9:57 PM: > > You mention an eight-core machine (8c?). Since I operate a dual-core > > system, would it make sense to increase my AG count slightly, to five > > or six? > > Dave didn't mention the disk configuration of his "workstation". I'm > guessing he's got a local RAID setup with 8-16 drives. 2 SSDs in RAID0. > AG count has a > direct relationship to the storage hardware, not the number of CPUs > (cores) in the system. Actually, I used 16 AGs because it's twice the number of CPU cores and I want to make sure that CPU parallel workloads (e.g. make -j 8) don't serialise on AG locks during allocation. IOWs, I laid it out that way precisely because of the number of CPUs in the system... And to point out the not-so-obvious, this is the _default layout_ that mkfs.xfs in the debian squeeze installer came up with. IOWs, mkfs.xfs did exactly what I wanted without me having to tweak _anything_. > If you have a 24 core system (2x Magny Cours) > and a single disk, creating an FS with 24 AGs will give you nothing, and > may actually impede performance due to all the extra head seeking across > those 24 AGs. In that case, you are right. Single spindle SRDs go backwards in performance pretty quickly once you go over 4 AGs... Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
