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From "B. Todd Burruss" <bburr...@real.com>
Subject Re: Persistently increasing read latency
Date Sat, 05 Dec 2009 00:08:09 GMT
procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu------
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
 5  1  29576  88400  27656 13797784    1    0    46   134    0    1  8  1 91  1  0

performance is definitely better now that caching is working, thx!

however, the pending tasks in compaction pool are still not decreasing
and i've reduced the load a bunch on the server.  i'll be doing another
test tonight with some modifications to my test client to simulate real
world a bit better.



On Fri, 2009-12-04 at 16:47 -0600, Jonathan Ellis wrote:
> how much does vmstat say is being used for cache?
> 
> if it's not most of the other 14, then read I/O doesn't sound like the culprit
> 
> On Fri, Dec 4, 2009 at 4:17 PM, B. Todd Burruss <bburruss@real.com> wrote:
> > thx for the tip.  i've allocated -Xmx2G for cassandra out of 16G.
> >
> >
> > On Fri, 2009-12-04 at 14:22 -0600, Brandon Williams wrote:
> >> On Fri, Dec 4, 2009 at 1:40 PM, B. Todd Burruss <bburruss@real.com>
> >> wrote:
> >>         i've actually allocatted plenty of RAM, but it isn't fully
> >>         used.  the
> >>         read performance dwindles well before reaching a RAM limit.
> >>
> >>
> >> You don't want to over-allocate memory to Cassandra, you want to leave
> >> as much free as you can so the OS can cache the reads for you.
> >>
> >>
> >> -Brandon
> >>
> >
> >
> >





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