Re: Scaling shared buffer eviction

On 04/09/14 14:42, Amit Kapila wrote:
> On Thu, Sep 4, 2014 at 8:00 AM, Mark Kirkwood <mark.kirkwood@catalyst.net.nz>
> wrote:
>>
>>
>> Hi Amit,
>>
>> Results look pretty good. Does it help in the read-write case too?
>
> Last time I ran the tpc-b test of pgbench (results of which are
> posted earlier in this thread), there doesn't seem to be any major
> gain for that, however for cases where read is predominant, you
> might see better gains.
>
> I am again planing to take that data in next few days.
>

FWIW below are some test results on the 60 core beast with this patch 
applied to 9.4. I'll need to do more runs to iron out the variation, but 
it looks like the patch helps the standard (write heavy) pgbench 
workload a little, and clearly helps the read only case.


4x E7-4890 15 cores each.
1 TB ram
16x Toshiba PX02SS SATA SSD
4x Samsung NVMe XS1715 PCIe SSD

Ubuntu 14.04  (Linux 3.13)
Postgres 9.4 beta2
+ buffer eviction patch v5

Pgbench

scale 2000

Non default params:

max_connections = 400;
shared_buffers = "10GB";
maintenance_work_mem = "1GB";
effective_io_concurrency = 10;
wal_buffers = "256MB";
checkpoint_segments = 1920;
checkpoint_completion_target = 0.8;
ssl = 'off';
wal_sync_method = 'open_datasync';

read write

elapsed 600s

Clients  | tps   | tps (unpatched)
---------+-------+----------------  6      |  8279 |  8328  12     | 16260 | 16381  24     | 23639 | 23451  48     |
31430| 31004  96     | 38516 | 34777 192     | 33535 | 32443 384     | 27978 | 25068 384     | 30589 | 28798
 


read only

elapsed 300s

Clients  | tps    | tps (unpatched)
---------+--------+----------------  6      |  57654 |  57255  12     | 111361 | 112360  24     | 220304 | 187967  48
 | 384567 | 230961  96     | 380309 | 241947 192     | 330865 | 214570 384     | 315516 | 207548
 


Regards

Mark