Hi *,
as I have read many postings from users using qemu, too, I would like
them to keep an eye on memory consumption.
I'm with qemu-1.0.1 and qemu-1.1.0-1 and linux-kernel 3.4.2/3.5.0-rc2.
If I restart a VM from cold, I do some readings, up to memory being
fully used ( cache/buffers), that is, VM started with:
-m 1024
and I can see RSS of 1.1g in top.
After doing some normal IOps testing with:
spew -v --raw -P -t -i 5 -b 4k -p random -B 4k 2G /tmp/doof.dat
so a 2G file, tested for IOps-performance with 4k blocks I get a pretty
good value for 5x write/read-after-write:
Total iterations: 5
Total runtime: 00:04:43
Total write transfer time (WTT): 00:02:15
Total write transfer rate (WTR): 77480.53 KiB/s
Total write IOPS: 19370.13 IOPS
Total read transfer time (RTT): 00:01:40
Total read transfer rate (RTR): 103823.12 KiB/s
Total read IOPS: 25955.78 IOPS
but at the cost of approx. 400MiB more memory used, showing now 1.5g.
Though it's not proportional, after next run I get 1.6g, then the
process slows down... two another runs and we break the 1.7g border...
But with the following settings in the global section of ceph.conf:
rbd_cache = true
rbd_cache_size=16777216
rbd_cache_max_dirty=8388608
rbd_cache_target_dirty=4194304
I cannot see, why we should waste 500+ MiB of memory ;) ( multiplied
with approx. 100 VM's running).
If same VM started with:
:rbd_cache=false
everything stays as it should.
Anybody with similar setup willing to do some testing?
Other than that: fast and stable release, it seems ;)
Thnx in @vance,
Oliver.
--
Oliver Francke
filoo GmbH
Moltkestraße 25a
33330 Gütersloh
HRB4355 AG Gütersloh
Geschäftsführer: S.Grewing | J.Rehpöhler | C.Kunz
Folgen Sie uns auf Twitter: http://twitter.com/filoogmbh
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