"Inaam Rana" <inaamrana@gmail.com> wrote:
> Did you had a chance to look into this any further? We, at EnterpriseDB,
> have done some testing on this patch (dbt2 runs) and it looks like we are
> getting the desired results, particularly so when we spread out both sync
> and write phases.
Thank you for testing! Yes, I'm cleaning the patch. I changed configuration
parameters to delay each phase in checkpoints from setting absolute times
(checkpoint_xxx_duration) to setting relative to checkpoint_timeout
(checkpoint_xxx_percent). Delay factors strongly depend on total checkpoint
lengths, so I think the relative method is better.
I tested the patch on my machine, too. The belows are the results of
pgbench with/without the patch. As you see, the patch is not a complete
solution -- 12s of response time is not satisfiable yet -- but it was
better than other possible settings we could choose now.
pgbench -s100 -c16 -t100000 on the machine with 1GB ram and one SCSI drive
| A | B | C | D |
--------------------------+--------+--------+--------+--------+bgwriter_all_maxpages | 5 | 5 | 60 |
120 |checkpoint_write_percent | 50.0 | 0 | 0 | 0 |checkpoint_nap_percent | 10.0 | 0 | 0
| 0 |checkpoint_sync_percent | 20.0 | 0 | 0 | 0 |
--------------------------+--------+--------+--------+--------+pgbench tps | 612.23 | 517.64 | 488.90 |
378.39|response average | 2.50ms | 2.89ms | 3.12ms | 3.99ms |response maximum | 12.23s |123.66s |
55.09s| 36.72s |
--------------------------+--------+--------+--------+--------+
A: Proposed configurations with patch
B: Default configurations
C: Make bgwriter aggressive
D: Make bgwriter more aggressive
Other configurations:
- full_page_writes = off
- wal_buffers = 4MB
- checkpoint_segments = 32
- checkpoint_timeout = 15min
Regards,
---
ITAGAKI Takahiro
NTT Open Source Software Center
