Monday, December 18, 2017

Sysbench: IO-bound and a fast server, part 2

This post has results for sysbench with an IO-bound workload and a fast server. It uses 1 table with 800M rows. The previous post had results for 8 tables with 100M rows/table. The goal is to understand the impact from more contention. Before that I published a report comparing sysbench with 8 tables vs 1 table for an in-memory workload.

All of the data is on github. With the exception of the scan section, the graphs below have the absolute QPS for 48 concurrent clients using 8 tables and 1 table.


  • MyRocks scans are up to 2X faster with readahead
  • update-one - all engines do worse. This is expected.
  • update-index - InnoDB 5.6 & 5.7 do worse. This doesn't repeat on the in-memory benchmark.
  • read-write - InnoDB 5.6 does better on the 1 table test. This is odd.
  • hot-points - all engines do worse. This is expected. MyRocks can do 3X better by switching from LRU to Clock once that feature is GA.
  • insert - InnoDB gets ~50% of the QPS with 1 table vs 8 tables.


This scan test uses one connection to scan the 800M row table. For the previous post there were 8 connections each scanning a different table with 100M rows/table. Fortunately the results here are similar to the results from the previous test.
  • InnoDB 5.6 is faster than MyRocks without readahead.
  • MyRocks with readahead is faster than InnoDB 5.6 but slower than InnoDB 5.7/8.0


All engines lose QPS with 1 table, the result is expected given all updates go to one row on this test. The result here is similar to the in-memory benchmark.

MyRocks and InnoDB 8.0 do great. InnoDB 5.6/5.7 lose QPS with 1 table but I did not debug that.

read-write range=100

Most engines do the same for 1 vs 8 tables. InnoDB 5.6 does much better with 1 table but I did not debug that.


All engines lose QPS with 1 table and this is similar to the in-memory benchmark. That is expected because the test fetches the same 100 rows per query and this stays in-memory. The QPS for MyRocks can be ~3X better by switching from using LRU to Clock for the block cache but that feature might not be GA today.


InnoDB gets ~2X more QPS with 8 tables than with 1. That result is similar to the in-memory benchmark. I didn't debug the source of contention.

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