Code review comment for lp:~zephyrleaves/percona-server/row_cache

> > I can't get good performance numbers with row cache.
> >
> > I am running sysbench oltp, ZipF distribution, 100GB database, 16 threads
> >
> > mysqld --innodb-buffer-pool-size=10GB --innodb-log-file-size=4G
> > --innodb_flush_log_at_trx_commit=1 --innodb_row_cache_mem_pool_size=10GB
> > --innodb_row_cache_on=ON
> >
> > with innodb_row_cache_mem_pool_size=10GB the results is actually worse then
> > with innodb_row_cache_mem_pool_size=5GB
> >
> > and in any case it is worse then with no row cache at all.
> >
> > I suspect it maybe a some mutex contention issue.
>
> You need use this sysbench
> http://code.google.com/p/row-cache-for-
> innodb/downloads/detail?name=sysbench-0.4.8.tar.gz
> for test.
> This sysbench which i modified for row cache's scene.
> You can use command like this to run test:
> sysbench --test=oltp --oltp-test-mode=simple --oltp-skip-trx=on --oltp-table-
> size=80000000 --oltp-range-size=1 --mysql-host=localhost --mysql-user=xx
> --mysql-password=xx --oltp-read-only=on --init-rng=on --num-threads=70 --oltp-
> dist-type=special --oltp-dist-pct=1 --oltp-dist-res=80 --max-requests=0 --max-
> time=1800 run
>
> Because of the common sysbench's oltp-dist-type is not random enough.

RowCache is good at for hot data and the hot data is distributed in random ,not continuous.