Added to TODO:
* SMP scalability improvements
http://archives.postgresql.org/pgsql-hackers/2007-07/msg00439.php
---
Simon Riggs wrote:
David Strong presented some excellent results of his SMP scalability
testing at
Add to TODO:
* SMP scalability improvements
http://archives.postgresql.org/pgsql-hackers/2007-07/msg00439.php
---
Simon Riggs wrote:
David Strong presented some excellent results of his SMP scalability
testing at
This has been saved for the 8.4 release:
http://momjian.postgresql.org/cgi-bin/pgpatches_hold
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Simon Riggs wrote:
David Strong presented some excellent results of his SMP scalability
testing at Ottawa in May.
The NUM_BUFFER_PARTITIONS patch is fairly simple. We've
noticed gains with NUM_BUFFER_PARTITIONS set between 256 and
2048, but little to no gain after 2048, although this might
depend on the benchmark and platform being used. We've
Might this also be a padding issue, because 2048
David Strong presented some excellent results of his SMP scalability
testing at Ottawa in May.
http://www.pgcon.org/2007/schedule/events/16.en.html
There are some easy things we can do to take advantage of those results,
especially the ones that were hardware independent.
The hardware
Simon Riggs wrote:
Proposals
1. For the first result, I suggest that we introduce some padding into
the shmem structure XLogCtlData to alleviate false sharing that may
exist between holders of WALInsertLock, WALWriteLock and info_lck. The
cost of this will be at most about 200 bytes of shmem,
Joshua D. Drake [EMAIL PROTECTED] writes:
+1 on the idea (I can speak to the technical side). What I can say is that it
is pretty much known that after 8 cores we slow down. Although 8.2 is better
than any other release in this regard.
Wait, what benchmarks have you seen where we slow down?
Gregory Stark wrote:
Joshua D. Drake [EMAIL PROTECTED] writes:
+1 on the idea (I can speak to the technical side). What I can say is that it
is pretty much known that after 8 cores we slow down. Although 8.2 is better
than any other release in this regard.
Wait, what benchmarks have you seen
Simon Riggs wrote:
Proposals
1. For the first result, I suggest that we introduce some padding
into
the shmem structure XLogCtlData to alleviate false sharing that may
exist between holders of WALInsertLock, WALWriteLock and info_lck.
The
cost of this will be at most about 200 bytes of
Joshua D. Drake wrote:
Gregory Stark wrote:
Joshua D. Drake [EMAIL PROTECTED] writes:
+1 on the idea (I can speak to the technical side). What I can say
is that it
is pretty much known that after 8 cores we slow down. Although 8.2
is better
than any other release in this regard.
Wait,
Andrew Dunstan wrote:
Joshua D. Drake wrote:
Gregory Stark wrote:
Joshua D. Drake [EMAIL PROTECTED] writes:
If I have 16 cores, things are still really loud but I start to not be
able to tell the difference. The percentage of improvement is much lower.
E.g, 16 cores works and
Simon Riggs [EMAIL PROTECTED] writes:
2. Increase NUM_BUFFER_PARTITIONS from 16 to 256 (or higher).
Do you have any evidence to back up such a large increase?
This change is not free; at the very least it will break
contrib/pg_buffercache, which wants to lock all the partitions at once.
To: Simon Riggs
Cc: pgsql-hackers@postgresql.org
Subject: Re: [HACKERS] Straightforward changes for increased SMP
scalability
Simon Riggs [EMAIL PROTECTED] writes:
2. Increase NUM_BUFFER_PARTITIONS from 16 to 256 (or higher).
Do you have any evidence to back up such a large increase
Strong, David [EMAIL PROTECTED] writes:
I'm happy to run some benchmarks to show the improvements with various
NUM_BUFFER_PARTITIONS settings. However, I want to make sure that this
is going to be useful. I can run 16 (base), 32, 64, 128 etc. type
increments, but I'm more concerned about the
I'm happy to run some benchmarks to show the improvements with
various
NUM_BUFFER_PARTITIONS settings. However, I want to make sure that
this
is going to be useful. I can run 16 (base), 32, 64, 128 etc. type
increments, but I'm more concerned about the number of cores to use.
Do
you have a
On Mon, Jul 16, 2007 at 01:23:46PM +0100, Simon Riggs wrote:
Both of these changes are simple enough to consider for 8.3
I'm in favour of scalability, of course, but are they really simple
enough to put in for 8.3? I was under the impression that there was
a push on to get the thing shipped,
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