On 09/13/2017 10:03 PM, Jens Axboe wrote: > On 09/13/2017 04:59 PM, Jens Axboe wrote: >> On 09/07/2017 01:59 PM, Dave Jiang wrote: >>> Jens, >>> fio can display completion latency percentages via the percentile_list >>> parameter. I can get p90 and p99 numbers for clat via >>> percentile_list=90:99. Is there a way to get the overall latency for >>> percentile? I'm interested in the total latency measurements for p90 and >>> p99 while doing some measurements on the persistent memory block driver >>> and playing around using DMA engines for transfer. >> >> If I understand correctly, you are using an IO engine that is async, and >> you want the latency percentiles to reflect total IO time >> (submission+completion), not just completion time? >> >> We can't currently do that, but it'd be trivial to do with an option of >> some sort. Currently the percentile enable option is clat_percentile, >> and it defaults to on. We could have a lat_percentile option that, if >> enabled, would change the reporting to being total IO time. IOW: >> >> clat_percentile=1 Latency percentiles are completion latencies >> lat_percentile=1 Latency percentiles are total IO time >> >> and have them be mutually exclusive. > > Something like the below. Please try it out and see if it works for you. Or just try current -git. I got cocky and just committed it. -- Jens Axboe -- To unsubscribe from this list: send the line "unsubscribe fio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
