Re: compression cpu overhead

To clarify, writes have no *immediate* cpu cost from adding the write to the memtable, however the compression overhead cost is paid when writing out a new SSTable (whether from flushing a memtable or compacting), correct? So it sounds like when reads >> writes then Tushar's comments are

Re: compression cpu overhead

For writes it's negligible. For reads it makes a significant difference for high tps and low latency workload. You would see up to 3x higher cpu with LZ4 vs no compression. It would be different for different h/w configurations. Thanks, Tushar (Sent from iPhone) > On Nov 3, 2015, at 5:51 PM,

Re: compression cpu overhead

Most concerned about write since that's where most of the cost is, but perf numbers for a any workload mix would be helpful. On Tue, Nov 3, 2015 at 3:48 PM, Graham Sanderson wrote: > On read or write? > > https://issues.apache.org/jira/browse/CASSANDRA-7039 and friends in 2.2 >

Re: compression cpu overhead

You won't see any overhead on writes because you don't actually write to sstables when performing a write. Just the commit log & memtable. Memtables are flushes asynchronously. > On Nov 4, 2015, at 1:57 AM, Tushar Agrawal wrote: > > For writes it's negligible. For

Re: compression cpu overhead

On read or write? https://issues.apache.org/jira/browse/CASSANDRA-7039 and friends in 2.2 should make some difference, I didn’t immediately find perf numbers though. > On Nov 3, 2015, at 5:42 PM, Dan Kinder wrote: >