Hi Todd. I hope you had a good weekend.
Exactly, I'm testing the latency of cold-cache reads from SATA disks and performance of difference schema designs as well. We currently using Elasticsearch for a analytic service. ES has a "clear cache API" feature, it makes me easy to test. Thanks. Jason. 2017-04-08 5:05 GMT+09:00 Todd Lipcon <t...@cloudera.com>: > Hey Jason, > > Can I ask what the purposes of the testing is? > > One thing to note is that we're currently leaving a fair bit of > performance on the table for cold-cache reads from spinning disks. So, if > you find that the performance is not satisfactory, it's worth being aware > that we will likely make some significant improvements in this area in the > future. > > https://issues.apache.org/jira/browse/KUDU-1289 has some details. > > -Todd > > On Fri, Apr 7, 2017 at 8:44 AM, Dan Burkert <danburk...@apache.org> wrote: > >> Hi Jason, >> >> There is no command to have Kudu evict its block cache, but restarting >> the tablet server process will have that effect. Ideally all written data >> will be flushed before the restart, otherwise startup/bootstrap will take a >> bit longer. Flushing typically happens within 60s of the last write. >> Waiting for flush and compaction is also a best-practice for read-only >> benchmarks. I'm not sure if someone else on the list has an easier way of >> determining when a flush happens, but I typically look at the 'MemRowSet' >> memory usage for the tablet on the /mem-trackers HTTP endpoint; it should >> show something minimal like 256B if it's fully flushed and empty. You can >> also see details about how much memory is in the block cache on that page, >> if that interests you. >> >> - Dan >> >> On Thu, Apr 6, 2017 at 11:23 PM, Jason Heo <jason.heo....@gmail.com> >> wrote: >> >>> Hi. >>> >>> I'm using Apache Kudu 1.2 on CDH 5.10. >>> >>> Currently, I'm doing a performance test of Kudu. >>> >>> Flushing OS Page Cache is easy, but I don't know how to flush >>> `block_cache_capacity_mb` easily. >>> >>> I currently execute SELECT statement over a unnecessarily table to evict >>> cached block of testing table. >>> >>> It is cumbersome, so I'd like to know is there a command for flushing >>> block caches (or another kudu's caches which I don't know yet) >>> >>> Thanks. >>> >>> Regards, >>> Jason >>> >> >> > > > -- > Todd Lipcon > Software Engineer, Cloudera >
