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From "Will @ SOHO" <w...@voodoolunchbox.com>
Subject Re: Row caching memory usage in Cassandra 1.0.x
Date Tue, 23 Oct 2012 01:13:11 GMT
On 10/22/2012 08:24 PM, aaron morton wrote:
> I'm not aware of how to track the memory usage for the off heap row 
> cache in 1.0. The memory may show up in something like JConsole. What 
> about seeing how much os memory is allocated to buffers and working 
> backwards from there?
>
> Anyone else ?
>
> (One thing to be away of is each CF has it's own row cache, so tuning 
> must be done per CF. )
>
> Cheers
> -----------------
> Aaron Morton
> Freelance Developer
> @aaronmorton
> http://www.thelastpickle.com
>
> On 23/10/2012, at 3:35 AM, Josh <jbuss@thebrighttag.com 
> <mailto:jbuss@thebrighttag.com>> wrote:
>
>> Hi, I'm hoping to get some help on how to help tune our 1.0.x cluster 
>> w.r.t. row
>> caching.
>>
>> We're using the netflix priam client, so unfortunately upgrading to 
>> 1.1.x is out
>> of the question for now.. but until we find a way around that, is 
>> there any way
>> to help determine where the 'sweet spot' is between heap size, row 
>> cache size,
>> and leaving the rest of the ram available to the OS?
>>
>> We're using the oracle jvm with jna so we can do the off-heap row 
>> caching, but
>> I'm not sure how to tell how much ram it's using, thus I'm not 
>> comfortable
>> increasing it further. (currently we have it set to 100,000 rows and 
>> we're
>> already seeing ~85% hit rates, so we've stopped upping it further for 
>> now).
>>
>> Thanks for any advice,
>>
>> -Josh
>>
>>
>>
>
ByteBuffer::AllocateDirect uses memlocking, i think. mLock takes a mask 
of "all current" and "all future". Most developers outside C/C++ word 
won't use "all future". So buffer counts * sizes should be reliable. 
Even with JNA, you'd be using the same system call.



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