From: Ben Nachtrieb <bnachtrieb@crescat.net>
To: "pgsql-performance@postgresql.org" <pgsql-performance@postgresql.org>
Subject: How does max_parallel_workers_per_gather change load averages?
Thread-Topic: How does max_parallel_workers_per_gather change load averages?
Thread-Index: AdM8fyQtw+iSK1wQSmyV8nuRQYnc0g==
Date: Tue, 3 Oct 2017 19:48:39 +0000
Message-ID: 
 <BN6PR1301MB2212820B17792E0E52802EC0D4720@BN6PR1301MB2212.namprd13.prod.outlook.com>
Accept-Language: en-US
Content-Language: en-US
received-spf: None (protection.outlook.com: crescat.net does not designate
 permitted sender hosts)
spamdiagnosticoutput: 1:99
spamdiagnosticmetadata: NSPM
Content-Type: multipart/alternative;
	boundary="_000_BN6PR1301MB2212820B17792E0E52802EC0D4720BN6PR1301MB2212_"
MIME-Version: 1.0
X-MS-Exchange-CrossTenant-originalarrivaltime: 03 Oct 2017 19:48:39.9868
 (UTC)
X-MS-Exchange-CrossTenant-fromentityheader: Hosted
X-MS-Exchange-CrossTenant-id: 142f3b9d-fb1f-4275-937a-0c090feb6430
X-MS-Exchange-Transport-CrossTenantHeadersStamped: BN6PR1301MB2065
List-Archive: <http://archives.postgresql.org/pgsql-performance>
List-Help: <mailto:majordomo@postgresql.org?body=help>
List-ID: <pgsql-performance.postgresql.org>
List-Owner: <mailto:pgsql-performance-owner@postgresql.org>
List-Post: <mailto:pgsql-performance@postgresql.org>
List-Subscribe: <mailto:majordomo@postgresql.org?body=sub%20pgsql-performance>
List-Unsubscribe: 
 <mailto:majordomo@postgresql.org?body=unsub%20pgsql-performance>
X-Mailing-List: pgsql-performance
Precedence: bulk
Sender: pgsql-performance-owner@postgresql.org

--_000_BN6PR1301MB2212820B17792E0E52802EC0D4720BN6PR1301MB2212_
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: quoted-printable

Hello,

This is my first question on this list.

How does max_parallel_workers_per_gather change Linux server load averages?

I have 2 cores and my max_parallel_workers_per_gather =3D 2 and max_worker_=
processes =3D 8, but my load averages are between 8 and 5 with scheduled at=
 1/189 to 5/195. Are these so high because I increased max_parallel_workers=
_per_gather? My understanding is that if my load averages are greater than =
my number of cores the system is overloaded. Should I think about it differ=
ently once I increase max_parallel_workers_per_gather? How should I think a=
bout it?

I am using postgres 9.6.


--_000_BN6PR1301MB2212820B17792E0E52802EC0D4720BN6PR1301MB2212_
Content-Type: text/html; charset="us-ascii"
Content-Transfer-Encoding: quoted-printable

<html xmlns:v=3D"urn:schemas-microsoft-com:vml" xmlns:o=3D"urn:schemas-micr=
osoft-com:office:office" xmlns:w=3D"urn:schemas-microsoft-com:office:word" =
xmlns:x=3D"urn:schemas-microsoft-com:office:excel" xmlns:m=3D"http://schema=
s.microsoft.com/office/2004/12/omml" xmlns=3D"http://www.w3.org/TR/REC-html=
40">
<head>
<meta http-equiv=3D"Content-Type" content=3D"text/html; charset=3Dus-ascii"=
>
<meta name=3D"Generator" content=3D"Microsoft Word 15 (filtered medium)">
<style><!--
/* Font Definitions */
@font-face
	{font-family:"Cambria Math";
	panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
	{font-family:Calibri;
	panose-1:2 15 5 2 2 2 4 3 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
	{margin:0in;
	margin-bottom:.0001pt;
	font-size:11.0pt;
	font-family:"Calibri",sans-serif;}
a:link, span.MsoHyperlink
	{mso-style-priority:99;
	color:#0563C1;
	text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
	{mso-style-priority:99;
	color:#954F72;
	text-decoration:underline;}
span.EmailStyle17
	{mso-style-type:personal-compose;
	font-family:"Calibri",sans-serif;
	color:windowtext;}
.MsoChpDefault
	{mso-style-type:export-only;
	font-family:"Calibri",sans-serif;}
@page WordSection1
	{size:8.5in 11.0in;
	margin:1.0in 1.0in 1.0in 1.0in;}
div.WordSection1
	{page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext=3D"edit" spidmax=3D"1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext=3D"edit">
<o:idmap v:ext=3D"edit" data=3D"1" />
</o:shapelayout></xml><![endif]-->
</head>
<body lang=3D"EN-US" link=3D"#0563C1" vlink=3D"#954F72">
<div class=3D"WordSection1">
<p class=3D"MsoNormal">Hello, <o:p></o:p></p>
<p class=3D"MsoNormal"><o:p>&nbsp;</o:p></p>
<p class=3D"MsoNormal">This is my first question on this list. <o:p></o:p><=
/p>
<p class=3D"MsoNormal"><o:p>&nbsp;</o:p></p>
<p class=3D"MsoNormal">How does max_parallel_workers_per_gather change Linu=
x server load averages?<o:p></o:p></p>
<p class=3D"MsoNormal"><o:p>&nbsp;</o:p></p>
<p class=3D"MsoNormal">I have 2 cores and my max_parallel_workers_per_gathe=
r =3D 2 and max_worker_processes =3D 8, but my load averages are between 8 =
and 5 with scheduled at 1/189 to 5/195. Are these so high because I increas=
ed max_parallel_workers_per_gather? My
 understanding is that if my load averages are greater than my number of co=
res the system is overloaded. Should I think about it differently once I in=
crease max_parallel_workers_per_gather? How should I think about it?<o:p></=
o:p></p>
<p class=3D"MsoNormal"><o:p>&nbsp;</o:p></p>
<p class=3D"MsoNormal">I am using postgres 9.6. <o:p></o:p></p>
<p class=3D"MsoNormal"><o:p>&nbsp;</o:p></p>
<p class=3D"MsoNormal"><o:p>&nbsp;</o:p></p>
<p class=3D"MsoNormal"><o:p>&nbsp;</o:p></p>
</div>
</body>
</html>

--_000_BN6PR1301MB2212820B17792E0E52802EC0D4720BN6PR1301MB2212_--