> Il giorno 18 ott 2017, alle ore 16:45, Jens Axboe <axboe@xxxxxxxxx> ha scritto: > > On 10/18/2017 07:19 AM, Tejun Heo wrote: >>> We tried to understand the reason for this high overhead, and, in >>> particular, to find out whether whether there was some issue that we >>> could address on our own. But the causes seem somehow substantial: >>> one of the most time-consuming operations needed by some blkg_*stats_* >>> functions is, e.g., find_next_bit, for which we don't see any trivial >>> replacement. >> >> Can you point to the specific ones? I can't find find_next_bit usages >> in generic blkg code. > > Yeah, in general a report like this is pretty much useless without > any sort of call traces or perf output. The best way to get help > is to post exactly what to run to reproduce the performance issue, > and profile output that shows/highlights the issues. > Yes, sorry. To be very brief, I just provided a link to the script with which one can immediately reproduce the issue. I hope the information I have now provided in my reply to Tejun are enough. Thanks, Paolo > -- > Jens Axboe >
