[email protected] said: > 3 properties can be edited in mpt.conf to tune the performance: > . . . > mpt_doneq_length_threshold_prop - default 8 > > This property is the tolerable backlog of completed IO operations at the > interrupt CPU for which I/O completion processing has not been performed. > While the backlog remains below this level, I/O completion callbacks will be > made in the traditional manner on the interrupt CPU. When the backlog > exceeds this level, the entire backlog will be transferred to one of the > helper threads.
Thanks for the suggestion, I'll give this a try today. I expect that since the V245 has only two single-core CPU's, there's not a lot of help to be had with this approach, but it still sounds encouraging. Do you (or anyone listening) know some DTrace code that will display the size of this backlog, for before/after comparison? I've done a bit of comparison against an X4150 using the same HBA connected to a J4400. The overall number of interrupts is the same as on this slow V245, for the same amount of I/O (and identical ZFS pool config). It's just the amount of time spent in the mpt driver (in calls to "mpt_check_dma_handle", according to DTrace) which is much longer on the V245. Are there some tuning knobs related to DMA, PCI-express transfers, etc. that might help? Regards, Marion _______________________________________________ storage-discuss mailing list [email protected] http://mail.opensolaris.org/mailman/listinfo/storage-discuss
