+ceph-devel to get input on whether we want/need to check the value of /dev/cpu_dma_latency (platform dependant) at startup and issue a warning, or whether documenting this would suffice? Any doc contribution would be welcomed. On Wed, May 3, 2017 at 7:18 PM, Blair Bethwaite <blair.bethwaite@xxxxxxxxx> wrote: > On 3 May 2017 at 19:07, Dan van der Ster <dan@xxxxxxxxxxxxxx> wrote: >> Whether cpu_dma_latency should be 0 or 1, I'm not sure yet. I assume >> your 30% boost was when going from throughput-performance to >> dma_latency=0, right? I'm trying to understand what is the incremental >> improvement from 1 to 0. > > Probably minimal given that represents a state transition latency > taking only 1us. Presumably the main issue is when the CPU can drop > into the lower states and the compounding impact of that over time. I > will do some simple characterisation of that over the next couple of > weeks and report back... > > -- > Cheers, > ~Blairo > _______________________________________________ > ceph-users mailing list > ceph-users@xxxxxxxxxxxxxx > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com -- Cheers, Brad _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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