在设置新的SQL Server时,我使用以下代码来确定MAXDOP设置的良好起点：
/*
This will recommend a MAXDOP setting appropriate for your machine's NUMA memory
configuration. You will need to evaluate this setting in a non-production
environment before moving it to production.
MAXDOP can be configured using:
EXEC sp_configure 'max degree of parallelism',X;
RECONFIGURE
If this instance is hosting a Sharepoint database,you MUST specify MAXDOP=1
(URL wrapped for readability)
http://blogs.msdn.com/b/rcormier/archive/2012/10/25/
you-shall-configure-your-maxdop-when-using-sharepoint-2013.aspx
Biztalk (all versions,including 2010):
MAXDOP = 1 is only required on the BizTalk Message Box
database server(s),and must not be changed; all other servers hosting other
BizTalk Server databases may return this value to 0 if set.
http://support.microsoft.com/kb/899000
*/
DECLARE @CoreCount int;
DECLARE @NumaNodes int;
SET @CoreCount = (SELECT i.cpu_count from sys.dm_os_sys_info i);
SET @NumaNodes = (
SELECT MAX(c.memory_node_id) + 1
FROM sys.dm_os_memory_clerks c
WHERE memory_node_id < 64
);
IF @CoreCount > 4 /* If less than 5 cores,don't bother. */
BEGIN
DECLARE @MaxDOP int;
/* 3/4 of Total Cores in Machine */
SET @MaxDOP = @CoreCount * 0.75;
/* if @MaxDOP is greater than the per NUMA node
Core Count,set @MaxDOP = per NUMA node core count
*/
IF @MaxDOP > (@CoreCount / @NumaNodes)
SET @MaxDOP = (@CoreCount / @NumaNodes) * 0.75;
/*
Reduce @MaxDOP to an even number
*/
SET @MaxDOP = @MaxDOP - (@MaxDOP % 2);
/* Cap MAXDOP at 8,according to Microsoft */
IF @MaxDOP > 8 SET @MaxDOP = 8;
PRINT 'Suggested MAXDOP = ' + CAST(@MaxDOP as varchar(max));
END
ELSE
BEGIN
PRINT 'Suggested MAXDOP = 0 since you have less than 4 cores total.';
PRINT 'This is the default setting,you likely do not need to do';
PRINT 'anything.';
END
我意识到这有点主观,可以根据很多事情而变化;但是我正在尝试创建一个紧凑的全部代码,用作新服务器的起点.
有没有人对此代码有任何意见？
解决方法
最好的方法是 – 使用coreinfo(sysinternals的实用程序),因为这会给你
a. Logical to Physical Processor Map b. Logical Processor to Socket Map c. Logical Processor to NUMA Node Map as below : Logical to Physical Processor Map: **---------------------- Physical Processor 0 (Hyperthreaded) --**-------------------- Physical Processor 1 (Hyperthreaded) ----**------------------ Physical Processor 2 (Hyperthreaded) ------**---------------- Physical Processor 3 (Hyperthreaded) --------**-------------- Physical Processor 4 (Hyperthreaded) ----------**------------ Physical Processor 5 (Hyperthreaded) ------------**---------- Physical Processor 6 (Hyperthreaded) --------------**-------- Physical Processor 7 (Hyperthreaded) ----------------**------ Physical Processor 8 (Hyperthreaded) ------------------**---- Physical Processor 9 (Hyperthreaded) --------------------**-- Physical Processor 10 (Hyperthreaded) ----------------------** Physical Processor 11 (Hyperthreaded) Logical Processor to Socket Map: ************------------ Socket 0 ------------************ Socket 1 Logical Processor to NUMA Node Map: ************------------ NUMA Node 0 ------------************ NUMA Node 1
现在,根据以上信息,理想MaxDop设置应计算为
a. It has 12 CPU’s which are hyper threaded giving us 24 CPUs. b. It has 2 NUMA node [Node 0 and 1] each having 12 CPU’s with Hyperthreading ON. c. Number of sockets are 2 [socket 0 and 1] which are housing 12 CPU’s each. Considering all above factors,the max degree of Parallelism should be set to 6 which is ideal value for server with above configuration.
所以答案是 – “这取决于”您的处理器占用空间和NUMA配置,下表将总结我上面解释的内容：
8 or less processors ===> 0 to N (where N= no. of processors)
More than 8 processors ===> 8
NUMA configured ===> MAXDOP should not exceed no of CPU’s assigned to each
NUMA node with max value capped to 8
Hyper threading Enabled ===> Should not exceed the number of physical processors.
编辑：下面是一个快速而脏的TSQL脚本,用于为MAXDOP设置生成建议
/*************************************************************************
Author : Kin Shah
Purpose : Recommend MaxDop settings for the server instance
Tested RDBMS : SQL Server 2008R2
**************************************************************************/
declare @hyperthreadingRatio bit
declare @logicalCPUs int
declare @HTEnabled int
declare @physicalCPU int
declare @SOCKET int
declare @logicalCPUPerNuma int
declare @NoOfNUMA int
select @logicalCPUs = cpu_count -- [Logical CPU Count],@hyperthreadingRatio = hyperthread_ratio -- [Hyperthread Ratio],@physicalCPU = cpu_count / hyperthread_ratio -- [Physical CPU Count],@HTEnabled = case
when cpu_count > hyperthread_ratio
then 1
else 0
end -- HTEnabled
from sys.dm_os_sys_info
option (recompile);
select @logicalCPUPerNuma = COUNT(parent_node_id) -- [NumberOfLogicalProcessorsPerNuma]
from sys.dm_os_schedulers
where [status] = 'VISIBLE ONLINE'
and parent_node_id < 64
group by parent_node_id
option (recompile);
select @NoOfNUMA = count(distinct parent_node_id)
from sys.dm_os_schedulers -- find NO OF NUMA Nodes
where [status] = 'VISIBLE ONLINE'
and parent_node_id < 64
-- Report the recommendations ....
select
--- 8 or less processors and NO HT enabled
case
when @logicalCPUs < 8
and @HTEnabled = 0
then 'MAXDOP setting should be : ' + CAST(@logicalCPUs as varchar(3))
--- 8 or more processors and NO HT enabled
when @logicalCPUs >= 8
and @HTEnabled = 0
then 'MAXDOP setting should be : 8'
--- 8 or more processors and HT enabled and NO NUMA
when @logicalCPUs >= 8
and @HTEnabled = 1
and @NoofNUMA = 1
then 'MaxDop setting should be : ' + CAST(@logicalCPUPerNuma / @physicalCPU as varchar(3))
--- 8 or more processors and HT enabled and NUMA
when @logicalCPUs >= 8
and @HTEnabled = 1
and @NoofNUMA > 1
then 'MaxDop setting should be : ' + CAST(@logicalCPUPerNuma / @physicalCPU as varchar(3))
else ''
end as Recommendations
编辑：对于未来的访客,你可以看看test-dbamaxdop powershell功能(以及other extremely helpful DBA functions(全部免费!!).
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