On Fri, Dec 20, 2013 at 6:19 PM, James Pearce <james@xxxxxxxxxxxx> wrote: > > "fio --size=100m --ioengine=libaio --invalidate=1 --direct=1 --numjobs=10 > --rw=read --name=fiojob --blocksize_range=4K-512k --iodepth=16" > > Since size=100m so reads would be entirely cached --invalidate=1 drops the cache, no? Our results of that particular fio test are consistently just under 1Gb/s on varied VMs running on varied HVs. BTW, look what happens when you don't drop the cache: # fio --size=100m --ioengine=libaio --invalidate=0 --direct=0 --numjobs=10 --rw=read --name=fiojob --blocksize_range=4K-512k | grep READ READ: io=1000.0MB, aggrb=4065.5MB/s, minb=416260KB/s, maxb=572067KB/s, mint=179msec, maxt=246msec > and, if hypervisor is > write-back, potentially many writes would never make it to the cluster as > well? Maybe you're right, but only if fio in randwrite mode overwrites the same address many times (does it??), and the rbd cache discards overwritten writes (does it??). By observation, I can say for certain that when we have those 10 VMs running these benchmarks in a while 1 loop, our cluster becomes quite busy. Cheers, Dan > > Sorry if I've misunderstood :) > > > _______________________________________________ > ceph-users mailing list > ceph-users@xxxxxxxxxxxxxx > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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