On 01/26/2017 05:42 PM, Jens Axboe wrote: > On 01/26/2017 09:35 AM, Hannes Reinecke wrote: >> On 01/25/2017 11:27 PM, Jens Axboe wrote: [ .. ] >>> And another variant, this one should be better in that it should result >>> in less queue runs and get better merging. Hope it works with your >>> stalls as well. >>> >>> >> >> Looking good; queue stalls are gone, and performance is okay-ish. >> I'm getting 84k IOPs now, which is not bad. > > Is that a tested-by? > Not yet; while doing the performance analysis the system now got a queue stalled with _legacy_ SQ. Need to figure out if it's my mpt3sas patches or something else. >> But we absolutely need to work on I/O merging; with CFQ I'm seeing >> requests having about double the size of those done by mq-deadline. >> (Bit unfair, I know :-) >> >> I'll be having some more data in time for LSF/MM. > > I agree, looking at the performance delta, it's all about merging. It's > fairly easy to observe with mq-deadline, as merging rates drop > proportionally to the number of queues configured. But even with 1 queue > with scsi-mq, we're still seeing lower merging rates than !mq + > deadline, for instance. > > I'll look at the merging case, it should not be that hard to bring at > least the single queue case to parity with !mq. I'm actually surprised > it isn't already. > Thanks. Cheers, Hannes -- Dr. Hannes Reinecke Teamlead Storage & Networking hare@xxxxxxx +49 911 74053 688 SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton HRB 21284 (AG Nürnberg) -- To unsubscribe from this list: send the line "unsubscribe linux-block" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
