Re: Blogbench RAID benchmarks

[Matthew Dillon <dillon@xxxxxxxxxxxxxxxxxxxx>]

:Disk performance should normally go up as the number of disk used increases
:(particularly for RAID0 setups), and this is the case on FreeBSD.
:Howewer, DragonFly seems to reach a plateau. The performance curve for writes
:is especially flat.
:
:FreeBSD performance numbers for the single disk test on the SATA controller
:are abysmal, but this is expected: the FreeBSD 8.2 kernel doesn't include
:an AHCI driver and uses the SATA disks in IDE compatibility mode.
:
:-- 
:Francois Tigeot

    That could be a CAM configuration issue.  Is this the arcmsr controller?
    Try this:  Change arcmsr.c's cam_sim_alloc() call from this:

acb->psim=cam_sim_alloc(arcmsr_action, arcmsr_poll, "arcmsr", acb, unit,
			&acb->qbuffer_lock,
			1,
			ARCMSR_MAX_OUTSTANDING_CMD, devq);

    To this:

acb->psim=cam_sim_alloc(arcmsr_action, arcmsr_poll, "arcmsr", acb, unit,
			&acb->qbuffer_lock,
			ARCMSR_MAX_OUTSTANDING_CMD,
			ARCMSR_MAX_OUTSTANDING_CMD, devq);

					-Matt