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Move unused buffers to freelist

From: Amit Kapila <amit(dot)kapila(at)huawei(dot)com>
To: "'PostgreSQL-development'" <pgsql-hackers(at)postgreSQL(dot)org>
Subject: Move unused buffers to freelist
Date: 2013-05-14 13:42:27
Message-ID: 002f01ce50a8$e057c7a0$a10756e0$@kapila@huawei.com (view raw or flat)
Thread:
Lists: pgsql-hackers
As discussed and concluded in mail thread
(http://www.postgresql.org/message-id/006f01ce34f0$d6fa8220$84ef8660$@kapila
@huawei.com), for moving unused buffer's to freelist end, 

I having implemented the idea and taken some performance data.

 

 

In the attached patch, bgwriter/checkpointer moves unused (usage_count =0 &&
refcount = 0) buffer's to end of freelist. I have implemented a new API
StrategyMoveBufferToFreeListEnd() to 

move buffer's to end of freelist.

 

Performance Data :

 

Configuration Details

O/S - Suse-11

RAM - 24GB

Number of Cores - 8

Server Conf - checkpoint_segments = 256; checkpoint_timeout = 25 min,
synchronous_commit = 0FF, shared_buffers = 5GB

Pgbench - Select-only

Scalefactor - 1200

Time - Each run is of 20 mins

 

Below data is for average 3 runs of 20 minutes

 

                        8C-8T                16C-16T            32C-32T
64C-64T

HEAD               11997               8455                 4989
2757

After Patch        19807               13296               8388
2821

 

Detailed each run data is attached with mail.

 

This is just the initial data, I will collect more data based on different
configuration of shared buffers and other configurations.

 

Feedback/Suggesions?

 

With Regards,

Amit Kapila.


Attachment: move_unsed_buffers_to_freelist.patch
Description: application/octet-stream (4.4 KB)
Attachment: move_unused_buffers_to_freelist.htm
Description: text/html (23.3 KB)

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