> -----Original Message----- > From: ceph-devel-owner@xxxxxxxxxxxxxxx [mailto:ceph-devel- > owner@xxxxxxxxxxxxxxx] On Behalf Of Bartlomiej Swiecki > Sent: Monday, November 28, 2016 8:22 AM > To: Ceph Development <ceph-devel@xxxxxxxxxxxxxxx> > Subject: Proposition - latency histogram > > Hi, > > > Currently we can query OSD for op latency but it's given as an average. > Average may not give > the bets information in this case - i.e. spikes can easily get hidden there. > > Instead of an average we could easily do a simple histogram - quantize the > latency into predefined set of time intervals, for each of them have a simple > performance counter, at each op increase one of them. Since those are per > OSD, we could have pretty high resolution with fractional memory usage, > performance impact should be negligible since only one (two if split into read > and write) of those counters would be incremented per one osd op. > +1 A reminder, there are different latency domains for the different media types (flash, HDD). One solution is to make the buckets be parameterized. > In addition we could also do this in 2D - each counter matching given latency > range and op size range. > having such 2D table would show both latency histogram, request size > histogram and combinations of those (i.e. latency histogram of ~4k ops only). > > What do you think about this idea? I can prepare some code - a simple proof > of concept looks really straightforward to implement. > > > Bartek > > -- > To unsubscribe from this list: send the line "unsubscribe ceph-devel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html ��.n��������+%������w��{.n����z��u���ܨ}���Ơz�j:+v�����w����ޙ��&�)ߡ�a����z�ޗ���ݢj��w�f
