Oleg Bartunov oleg@sai.msu.su writes:
I see a very low performance and high context switches on our
dual itanium2 slackware box (Linux ptah 2.6.14 #1 SMP)
with 8Gb of RAM, running 8.1_STABLE. Any tips here ?
[EMAIL PROTECTED]:~/cvs/8.1/pgsql/contrib/pgbench$ time pgbench -s 10 -c 10
-t 3000
Message-
From: Anjan Dave
Sent: Wed 12/7/2005 10:54 AM
To: Tom Lane
Cc: Vivek Khera; Postgresql Performance
Subject: Re: [PERFORM] High context switches occurring
Thanks for your inputs, Tom. I was going after high
Subject: Re: [PERFORM] High context switches occurring
Thanks for your inputs, Tom. I was going after high concurrent clients,
but should have read this carefully -
-s scaling_factor
this should be used with -i (initialize) option
To: Tom Lane
Cc: Vivek Khera; Postgresql Performance
Subject: Re: [PERFORM] High context switches occurring
Thanks for your inputs, Tom. I was going after high concurrent clients,
but should have read this carefully -
-s scaling_factor
Subject: Re: [PERFORM] High context switches occurring
Thanks for your inputs, Tom. I was going after high concurrent
clients,
but should have read this carefully -
-s scaling_factor
this should be used with -i (initialize) option.
number
Bruce Momjian pgman@candle.pha.pa.us writes:
Tom Lane wrote:
1. You don't want number of clients (-c) much higher than scaling factor
(-s in the initialization step).
Should we throw a warning when someone runs the test this way?
Not a bad idea (though of course only for the standard
contention.
I'll rerun the tests.
Thanks,
Anjan
-Original Message-
From: Tom Lane [mailto:[EMAIL PROTECTED]
Sent: Tuesday, December 06, 2005 6:45 PM
To: Anjan Dave
Cc: Vivek Khera; Postgresql Performance
Subject: Re: [PERFORM] High context switches occurring
Anjan Dave [EMAIL PROTECTED
On Tue, 2005-12-06 at 22:49, Tom Lane wrote:
Bruce Momjian pgman@candle.pha.pa.us writes:
Tom Lane wrote:
1. You don't want number of clients (-c) much higher than scaling factor
(-s in the initialization step).
Should we throw a warning when someone runs the test this way?
Not a bad
]
Sent: Tuesday, November 22, 2005 2:42 PM
To: Anjan Dave
Cc: Vivek Khera; Postgresql Performance
Subject: Re: [PERFORM] High context switches occurring
Anjan Dave [EMAIL PROTECTED] writes:
Would this problem change it's nature in any way on the recent
Dual-Core
Intel XEON MP machines?
Probably
On Dec 6, 2005, at 2:04 PM, Anjan Dave wrote:
interestingly, it was experiencing 3x more context switches than the
Intel box (upto 100k, versus ~30k avg on Dell). Both are RH4.0
I'll assume that's context switches per second... so for the opteron
that's 6540 cs's and for the Dell
Anjan Dave [EMAIL PROTECTED] writes:
-bash-3.00$ time pgbench -c 1000 -t 30 pgbench
starting vacuum...end.
transaction type: TPC-B (sort of)
scaling factor: 1
number of clients: 1000
number of transactions per client: 30
number of transactions actually processed: 3/3
tps =
Tom Lane wrote:
Anjan Dave [EMAIL PROTECTED] writes:
-bash-3.00$ time pgbench -c 1000 -t 30 pgbench
starting vacuum...end.
transaction type: TPC-B (sort of)
scaling factor: 1
number of clients: 1000
number of transactions per client: 30
number of transactions actually processed:
Bruce Momjian pgman@candle.pha.pa.us writes:
Tom Lane wrote:
1. You don't want number of clients (-c) much higher than scaling factor
(-s in the initialization step).
Should we throw a warning when someone runs the test this way?
Not a bad idea (though of course only for the standard
PM
To: Anjan Dave
Cc: Tom Lane; Vivek Khera; Postgresql Performance
Subject: Re: [PERFORM] High context switches occurring
On Tue, 2005-11-22 at 14:33, Anjan Dave wrote:
Is there any way to get a temporary relief from this Context Switching
storm? Does restarting postmaster help?
It seems
On Tue, 2005-11-22 at 18:17 -0500, Anjan Dave wrote:
It's mostly a 'read' application, I increased the vm.max-readahead to
2048 from the default 256, after which I've not seen the CS storm,
though it could be incidental.
Can you verify this, please?
Turn it back down again, try the test,
, 2005 1:14 PM
To: Anjan Dave
Cc: Scott Marlowe; Tom Lane; Vivek Khera; Postgresql Performance
Subject: Re: [PERFORM] High context switches occurring
On Tue, 2005-11-22 at 18:17 -0500, Anjan Dave wrote:
It's mostly a 'read' application, I increased the vm.max-readahead to
2048 from the default 256
1:33 PM
To: Simon Riggs
Cc: Scott Marlowe; Tom Lane; Vivek Khera; Postgresql Performance
Subject: Re: [PERFORM] High context switches occurring
The offending SELECT query that invoked the CS storm was optimized by
folks here last night, so it's hard to say if the VM setting made a
difference. I'll
Hi,
One of our PG server is experiencing extreme slowness and
there are hundreds of SELECTS building up. I am not sure if heavy context
switching is the cause of this or something else is causing it.
Is this pretty much the final word on this issue?
On Nov 22, 2005, at 11:59 AM, Anjan Dave wrote: This is a Dell Quad XEON. Hyperthreading is turned on, and I am planning to turn it off as soon as I get a chance to bring it down.You should probably also upgrade to Pg 8.0 or newer since it is a known problem with XEON processors and older postgres
Vivek Khera [EMAIL PROTECTED] writes:
On Nov 22, 2005, at 11:59 AM, Anjan Dave wrote:
This is a Dell Quad XEON. Hyperthreading is turned on, and I am
planning to turn it off as soon as I get a chance to bring it down.
You should probably also upgrade to Pg 8.0 or newer since it is a
Cc: Postgresql Performance; Anjan Dave
Subject: Re: [PERFORM] High context switches occurring
Vivek Khera [EMAIL PROTECTED] writes:
On Nov 22, 2005, at 11:59 AM, Anjan Dave wrote:
This is a Dell Quad XEON. Hyperthreading is turned on, and I am
planning to turn it off as soon as I get a chance
Anjan Dave [EMAIL PROTECTED] writes:
Would this problem change it's nature in any way on the recent Dual-Core
Intel XEON MP machines?
Probably not much.
There's some evidence that Opterons have less of a problem than Xeons
in multi-chip configurations, but we've seen CS thrashing on Opterons
of queries...
Thanks,
Anjan
-Original Message-
From: Anjan Dave
Sent: Tuesday, November 22, 2005 2:24 PM
To: Tom Lane; Vivek Khera
Cc: Postgresql Performance
Subject: Re: [PERFORM] High context switches occurring
Thanks, guys, I'll start planning on upgrading to PG8.1
Would this problem
P.s., followup to my last post, I don't know if turning of HT actually
lowered the number of context switches, just that it made my server run
faster.
---(end of broadcast)---
TIP 3: Have you checked our extensive FAQ?
On Tue, 2005-11-22 at 14:33, Anjan Dave wrote:
Is there any way to get a temporary relief from this Context Switching
storm? Does restarting postmaster help?
It seems that I can recreate the heavy CS with just one SELECT
statement...and then when multiple such SELECT queries are coming in,
-
From: Scott Marlowe [mailto:[EMAIL PROTECTED]
Sent: Tuesday, November 22, 2005 3:38 PM
To: Anjan Dave
Cc: Tom Lane; Vivek Khera; Postgresql Performance
Subject: Re: [PERFORM] High context switches occurring
On Tue, 2005-11-22 at 14:33, Anjan Dave wrote:
Is there any way to get a temporary
26 matches
Mail list logo
