I have been doing some testing on a fileserver recently donated to TNF. The system has an Areca 1280 controller (arcmsr driver) with a single RAID6 volume configured on 12 disks; 32GB of RAM; two quad-core Xeon L5420 CPUs.
I have tested under NetBSD-6 and NetBSD-current as well as the tls-maxphys branch. The test is a 'dd bs=2m of=/test count=65536". Write throughput, while acceptable (300-350MB/sec; 350-400MB/sec with tls-maxphys) is about 2/3 what I get on the same hardware under Linux. Read throughput is less good, 250-300MB/sec. The filesystem is FFSv2, 32k block/4k frag, with WAPBL. Watching systat while I do the dd tests, I see up to 70,000 TLB shootdown IPIs per second. Is this really right? I am not sure I know how to count these under Linux but I don't see any evidence of them. Is there a pmap problem? I'm running port-amd64. I have also seen some other odd things I'll detail elsewhere, but just for a start, can anyone explain to me whether this number of TLB shootdowns should be expected, whether each should really generate its own IPI, and what the performance impact may be? -- Thor Lancelot Simon [email protected] It's very complicated. It's very cumbersome. There's a lot of numbers involved with it.
