Re: Improvement of checkpoint IO scheduler for stable transaction responses

Hi,

I tested and changed segsize=0.25GB which is max partitioned table file size and
default setting is 1GB in configure option (./configure --with-segsize=0.25).
Because I thought that small segsize is good for fsync phase and background disk
write in OS in checkpoint. I got significant improvements in DBT-2 result!

* Performance result in DBT-2 (WH340)
                              | NOTPM    90%tile    Average  Maximum
 -----------------------------+---------------------------------------
 original_0.7 (baseline)      | 3474.62  18.348328  5.739    36.977713
 fsync + write                | 3586.85  14.459486  4.960    27.266958
 fsync + write + segsize=0.25 | 3661.17  8.28816    4.117    17.23191

Changing segsize with my checkpoint patches improved original over 50% at 90%tile
and maximum response time.

However, this tests ware not same condition... I also changed SESSION parameter
100 to 300 in DBT-2 driver. In general, I heard good SESSION parameter is 100.
Andt I didn't understand optimized DBT-2 parameters a lot. So I will retry to
test my patches and baseline with optimized parameters in DBT-2. Please wait for
a while.

Best regards,
--
Mitsumasa KONDO
NTT Open Source Software Center