Changed memtable_total_space_in_mb to 1024 still no luck.
On Fri, Dec 6, 2013 at 11:05 AM, Vicky Kak <vicky....@gmail.com> wrote: > Can you set the memtable_total_space_in_mb value, it is defaulting to 1/3 > which is 8/3 ~ 2.6 gb in capacity > > http://www.datastax.com/dev/blog/whats-new-in-cassandra-1-0-improved-memory-and-disk-space-management > > The flushing of 2.6 gb to the disk might slow the performance if > frequently called, may be you have lots of write operations going on. > > > > On Fri, Dec 6, 2013 at 10:06 PM, srmore <comom...@gmail.com> wrote: > >> >> >> >> On Fri, Dec 6, 2013 at 9:59 AM, Vicky Kak <vicky....@gmail.com> wrote: >> >>> You have passed the JVM configurations and not the cassandra >>> configurations which is in cassandra.yaml. >>> >> >> Apologies, was tuning JVM and that's what was in my mind. >> Here are the cassandra settings http://pastebin.com/uN42GgYT >> >> >> >>> The spikes are not that significant in our case and we are running the >>> cluster with 1.7 gb heap. >>> >>> Are these spikes causing any issue at your end? >>> >> >> There are no big spikes, the overall performance seems to be about 40% >> low. >> >> >>> >>> >>> >>> >>> On Fri, Dec 6, 2013 at 9:10 PM, srmore <comom...@gmail.com> wrote: >>> >>>> >>>> >>>> >>>> On Fri, Dec 6, 2013 at 9:32 AM, Vicky Kak <vicky....@gmail.com> wrote: >>>> >>>>> Hard to say much without knowing about the cassandra configurations. >>>>> >>>> >>>> The cassandra configuration is >>>> -Xms8G >>>> -Xmx8G >>>> -Xmn800m >>>> -XX:+UseParNewGC >>>> -XX:+UseConcMarkSweepGC >>>> -XX:+CMSParallelRemarkEnabled >>>> -XX:SurvivorRatio=4 >>>> -XX:MaxTenuringThreshold=2 >>>> -XX:CMSInitiatingOccupancyFraction=75 >>>> -XX:+UseCMSInitiatingOccupancyOnly >>>> >>>> >>>> >>>>> Yes compactions/GC's could skipe the CPU, I had similar behavior with >>>>> my setup. >>>>> >>>> >>>> Were you able to get around it ? >>>> >>>> >>>>> >>>>> -VK >>>>> >>>>> >>>>> On Fri, Dec 6, 2013 at 7:40 PM, srmore <comom...@gmail.com> wrote: >>>>> >>>>>> We have a 3 node cluster running cassandra 1.2.12, they are pretty >>>>>> big machines 64G ram with 16 cores, cassandra heap is 8G. >>>>>> >>>>>> The interesting observation is that, when I send traffic to one node >>>>>> its performance is 2x more than when I send traffic to all the nodes. We >>>>>> ran 1.0.11 on the same box and we observed a slight dip but not half as >>>>>> seen with 1.2.12. In both the cases we were writing with LOCAL_QUORUM. >>>>>> Changing CL to ONE make a slight improvement but not much. >>>>>> >>>>>> The read_Repair_chance is 0.1. We see some compactions running. >>>>>> >>>>>> following is my iostat -x output, sda is the ssd (for commit log) and >>>>>> sdb is the spinner. >>>>>> >>>>>> avg-cpu: %user %nice %system %iowait %steal %idle >>>>>> 66.46 0.00 8.95 0.01 0.00 24.58 >>>>>> >>>>>> Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s >>>>>> avgrq-sz avgqu-sz await svctm %util >>>>>> sda 0.00 27.60 0.00 4.40 0.00 256.00 >>>>>> 58.18 0.01 2.55 1.32 0.58 >>>>>> sda1 0.00 0.00 0.00 0.00 0.00 0.00 >>>>>> 0.00 0.00 0.00 0.00 0.00 >>>>>> sda2 0.00 27.60 0.00 4.40 0.00 256.00 >>>>>> 58.18 0.01 2.55 1.32 0.58 >>>>>> sdb 0.00 0.00 0.00 0.00 0.00 0.00 >>>>>> 0.00 0.00 0.00 0.00 0.00 >>>>>> sdb1 0.00 0.00 0.00 0.00 0.00 0.00 >>>>>> 0.00 0.00 0.00 0.00 0.00 >>>>>> dm-0 0.00 0.00 0.00 0.00 0.00 0.00 >>>>>> 0.00 0.00 0.00 0.00 0.00 >>>>>> dm-1 0.00 0.00 0.00 0.60 0.00 4.80 >>>>>> 8.00 0.00 5.33 2.67 0.16 >>>>>> dm-2 0.00 0.00 0.00 0.00 0.00 0.00 >>>>>> 0.00 0.00 0.00 0.00 0.00 >>>>>> dm-3 0.00 0.00 0.00 24.80 0.00 198.40 >>>>>> 8.00 0.24 9.80 0.13 0.32 >>>>>> dm-4 0.00 0.00 0.00 6.60 0.00 52.80 >>>>>> 8.00 0.01 1.36 0.55 0.36 >>>>>> dm-5 0.00 0.00 0.00 0.00 0.00 0.00 >>>>>> 0.00 0.00 0.00 0.00 0.00 >>>>>> dm-6 0.00 0.00 0.00 24.80 0.00 198.40 >>>>>> 8.00 0.29 11.60 0.13 0.32 >>>>>> >>>>>> >>>>>> >>>>>> I can see I am cpu bound here but couldn't figure out exactly what is >>>>>> causing it, is this caused by GC or Compaction ? I am thinking it is >>>>>> compaction, I see a lot of context switches and interrupts in my vmstat >>>>>> output. >>>>>> >>>>>> I don't see GC activity in the logs but see some compaction activity. >>>>>> Has anyone seen this ? or know what can be done to free up the CPU. >>>>>> >>>>>> Thanks, >>>>>> Sandeep >>>>>> >>>>>> >>>>>> >>>>> >>>> >>> >> >
