Hi Thanks for your comments I'll indeed put the OS Controller on, when we get our replacement CPU's and try what you described here. If there isn't any guide for this yet, should there be? Br, Tuomas -----Original Message----- From: ceph-users [mailto:ceph-users-bounces@xxxxxxxxxxxxxx] On Behalf Of Jan Schermer Sent: 26. toukokuuta 2015 19:18 To: Robert LeBlanc Cc: ceph-users Subject: Re: Performance and CPU load on HP servers running ceph (DL380 G6, should apply to others too) It should be noted that not all power saving is bad - you can save a lot of power by enabling some sleep states, throttling down, idling, or enabling low voltage mode on memory, with zero performance impact. In the end you can end up with more performance because of higher Turbo Boost TDP reserve and less thermal throttling (which you should never see in a well cooled datacentre, but it pops up from time to time as an issue). Enabling stuff like ?Performance mode? in BIOS usually just says ?act predictably?, which doesn?t imply it?s performing optimally at all. This is where you?ll find the most difference between vendors and how they tune their default settings. Lots of corporates don?t care and just switch to ?Performance? everywhere and trust the vendor to do the right thing, which is seldom the case when you?re on the budget :) Jan > On 26 May 2015, at 18:07, Robert LeBlanc <robert at leblancnet.us> wrote: > > Signed PGP part > In my experience with HP hardware, it was set to Econo mode in the > BIOS which is just plain junk. It will halt cores without respect to > workload to provide energy savings. > > We found that by setting the power mode to "OS controlled" we got > almost the same performance as the "Max performance" setting, but > while at the same time consuming about the same power as the Econo > mode. The kernel is much better at putting cores to sleep, making sure > there is adequate reserve capacity, and making sure that they are > woken up faster when load is increasing. By selecting "Econo or max > performance" profiles, the CPU loses control of the sleep states. My > recommendation is before tweaking any other setting, change the > performance profile to "OS controlled" and then go from there. > > ---------------- > Robert LeBlanc > GPG Fingerprint 79A2 9CA4 6CC4 45DD A904 C70E E654 3BB2 FA62 B9F1 > > > On Tue, May 26, 2015 at 5:53 AM, Lionel Bouton <lionel+ceph at bouton.name> wrote: > > On 05/26/15 10:06, Jan Schermer wrote: > > > > Turbo Boost will not hurt performance. Unless you have 100% load on > > all cores it will actually improve performance (vastly, in terms of > > bursty workloads). > > The issue you have could be related to CPU cores going to sleep mode. > > > > > > Another possibility is that the system is overheating when Turbo > > Boost is enabled. In this case it protects itself by throttling back > > the core frequencies to a very low value (it may use other means > > too, like lowering the system buses frequencies, halting the cores > > periodically, ...). This would explain the high loads. > > If the system switches back and forth between normal loads and huge > > loads and you can link that to CPU package temperature (and/or very > > low CPU core frequencies), this is probably the cause. If the > > ambient temperature isn't a problem (below 25?C any system should be > > fine and most can tolerate 30?C or > > more) then you have an internal cooling problem. > > > > Best regards, > > > > Lionel > > > > _______________________________________________ > > ceph-users mailing list > > ceph-users at lists.ceph.com > > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > > _______________________________________________ ceph-users mailing list ceph-users at lists.ceph.com http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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