On Tue, Dec 10, 2013 at 2:06 PM, Claudio Freire wrote:
> On Tue, Dec 10, 2013 at 5:03 PM, Merlin Moncure wrote:
>> Also, can I see a typical 'top' during poor scaling count(*) activity?
>> In particular, what's sys cpu%. I'm guessing it's non trivial.
>
>
> There was another thread, this seems l
On Tue, Dec 10, 2013 at 5:03 PM, Merlin Moncure wrote:
> Also, can I see a typical 'top' during poor scaling count(*) activity?
> In particular, what's sys cpu%. I'm guessing it's non trivial.
There was another thread, this seems like a mistaken double post or
something like that.
In that othe
On Wed, Nov 27, 2013 at 2:28 AM, Metin Doslu wrote:
> We have several independent tables on a multi-core machine serving Select
> queries. These tables fit into memory; and each Select queries goes over one
> table's pages sequentially. In this experiment, there are no indexes or
> table joins.
>
On Thu, Dec 5, 2013 at 1:03 PM, Metin Doslu wrote:
>> From what I've seen so far the bigger problem than contention in the
>> lwlocks itself, is the spinlock protecting the lwlocks...
>
> Postgres 9.3.1 also reports spindelay, it seems that there is no contention
> on spinlocks.
Did you check hu
> From what I've seen so far the bigger problem than contention in the
> lwlocks itself, is the spinlock protecting the lwlocks...
Postgres 9.3.1 also reports spindelay, it seems that there is no contention
on spinlocks.
PID 21121 lwlock 0: shacq 0 exacq 33 blk 1 spindelay 0
PID 21121 lwlock 33:
On 2013-12-05 11:33:29 +0200, Metin Doslu wrote:
> > Is your workload bigger than RAM?
>
> RAM is bigger than workload (more than a couple of times).
> > I think a good bit of the contention
> > you're seeing in that listing is populating shared_buffers - and might
> > actually vanish once you're
> Is your workload bigger than RAM?
RAM is bigger than workload (more than a couple of times).
> I think a good bit of the contention
> you're seeing in that listing is populating shared_buffers - and might
> actually vanish once you're halfway cached.
> From what I've seen so far the bigger prob
On 2013-12-05 11:15:20 +0200, Metin Doslu wrote:
> > - When we increased NUM_BUFFER_PARTITIONS to 1024, this problem is
> > disappeared for 8 core machines and come back with 16 core machines on
> > Amazon EC2. Would it be related with PostgreSQL locking mechanism?
>
> If we build with -DLWLOCK_ST
> - When we increased NUM_BUFFER_PARTITIONS to 1024, this problem is
> disappeared for 8 core machines and come back with 16 core machines on
> Amazon EC2. Would it be related with PostgreSQL locking mechanism?
If we build with -DLWLOCK_STATS to print locking stats from PostgreSQL, we
see tons of
On Wed, Dec 4, 2013 at 11:49 PM, Metin Doslu wrote:
> Here are some extra information:
>
> - When we increased NUM_BUFFER_PARTITIONS to 1024, this problem is
> disappeared for 8 core machines and come back with 16 core machines on
> Amazon EC2. Would it be related with PostgreSQL locking mechanism
We have several independent tables on a multi-core machine serving Select
queries. These tables fit into memory; and each Select queries goes over
one table's pages sequentially. In this experiment, there are no indexes or
table joins.
When we send concurrent Select queries to these tables, query
Here are some extra information:
- When we increased NUM_BUFFER_PARTITIONS to 1024, this problem is
disappeared for 8 core machines and come back with 16 core machines on
Amazon EC2. Would it be related with PostgreSQL locking mechanism?
- I tried this test with 4 core machines including my perso
> Maybe you could help test this patch:
>
http://www.postgresql.org/message-id/20131115194725.gg5...@awork2.anarazel.de
Which repository should I apply these patches. I tried main repository, 9.3
stable and source code of 9.3.1, and in my trials at least of one the
patches is failed. What patch co
On Tue, Dec 3, 2013 at 1:24 PM, Metin Doslu wrote:
> Looking into syncscan.c, it says in comments:
>
> "When multiple backends run a sequential scan on the same table, we try to
> keep them synchronized to reduce the overall I/O needed."
>
> But in my workload, every process was running on a diffe
Looking into syncscan.c, it says in comments:
"When multiple backends run a sequential scan on the same table, we try to
keep them synchronized to reduce the overall I/O needed."
But in my workload, every process was running on a different table.
On Tue, Dec 3, 2013 at 5:56 PM, Claudio Freire
On Tue, Dec 3, 2013 at 10:49 AM, Metin Doslu wrote:
> We have several independent tables on a multi-core machine serving Select
> queries. These tables fit into memory; and each Select queries goes over one
> table's pages sequentially. In this experiment, there are no indexes or
> table joins.
>
Metin Doslu wrote:
> When we send concurrent Select queries to these tables, query performance
> doesn't scale out with the number of CPU cores. We find that complex Select
> queries scale out better than simpler ones. We also find that increasing
> the block size from 8 KB to 32 KB, or increasing
We have several independent tables on a multi-core machine serving Select
queries. These tables fit into memory; and each Select queries goes over
one table's pages sequentially. In this experiment, there are no indexes or
table joins.
When we send concurrent Select queries to these tables, query
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