On Sun, Apr 9, 2017 at 6:38 PM, Jason Heo <[email protected]> wrote:
> 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. > > Makes sense. I don't think it would be particularly difficult to add such an API. Any interest in contributing a patch? I'm happy to point you in the right direction, if so. -Todd > 2017-04-08 5:05 GMT+09:00 Todd Lipcon <[email protected]>: > >> 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 <[email protected]> >> 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 <[email protected]> >>> 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 >> > > -- Todd Lipcon Software Engineer, Cloudera
