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sp_BlitzFirst: Made the sys.dm_os_ring_buffers CPU checks respect Linux always setting system_idle to 0. #3717

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sp_BlitzFirst: Made the sys.dm_os_ring_buffers CPU checks respect Linux always setting system_idle to 0. #3717

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73 changes: 56 additions & 17 deletions sp_BlitzFirst.sql
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Original file line number Diff line number Diff line change
Expand Up @@ -145,7 +145,18 @@ DECLARE @StringToExecute NVARCHAR(MAX),
@get_thread_time_ms NVARCHAR(MAX) = N'',
@thread_time_ms FLOAT = 0,
@logical_processors INT = 0,
@max_worker_threads INT = 0;
@max_worker_threads INT = 0,
@is_windows_operating_system BIT = 1;

IF EXISTS
(
SELECT 1
FROM sys.all_objects
WHERE name = 'dm_os_host_info'
)
BEGIN
SELECT @is_windows_operating_system = CASE WHEN host_platform = 'Windows' THEN 1 ELSE 0 END FROM sys.dm_os_host_info;
END;

/* Sanitize our inputs */
SELECT
Expand Down Expand Up @@ -2399,19 +2410,28 @@ If one of them is a lead blocker, consider killing that query.'' AS HowToStopit,
RAISERROR('Running CheckID 24',10,1) WITH NOWAIT;
END

/* Traditionally, we use 100 - SystemIdle here.
However, SystemIdle is always 0 on Linux.
So if we are on Linux, we use ProcessUtilization instead.
This is the approach found in
https://techcommunity.microsoft.com/blog/sqlserver/sql-server-cpu-usage-available-in-sys-dm-os-ring-buffers-dmv-starting-sql-server/825361 */
INSERT INTO #BlitzFirstResults (CheckID, Priority, FindingsGroup, Finding, Details, DetailsInt, URL)
SELECT 24, 50, 'Server Performance', 'High CPU Utilization', CAST(100 - SystemIdle AS NVARCHAR(20)) + N'%.', 100 - SystemIdle, 'https://www.brentozar.com/go/cpu'
SELECT 24, 50, 'Server Performance', 'High CPU Utilization', CAST(CpuUsage AS NVARCHAR(20)) + N'%.', CpuUsage, 'https://www.brentozar.com/go/cpu'
FROM (
SELECT CASE WHEN @is_windows_operating_system = 1 THEN 100 - SystemIdle ELSE ProcessUtilization END AS CpuUsage
FROM (
SELECT record,
record.value('(./Record/SchedulerMonitorEvent/SystemHealth/SystemIdle)[1]', 'int') AS SystemIdle
record.value('(./Record/SchedulerMonitorEvent/SystemHealth/SystemIdle)[1]', 'int') AS SystemIdle,
record.value('(./Record/SchedulerMonitorEvent/SystemHealth/ProcessUtilization)[1]', 'int') AS ProcessUtilization
FROM (
SELECT TOP 1 CONVERT(XML, record) AS record
FROM sys.dm_os_ring_buffers
WHERE ring_buffer_type = N'RING_BUFFER_SCHEDULER_MONITOR'
AND record LIKE '%<SystemHealth>%'
ORDER BY timestamp DESC) AS rb
) AS y
WHERE 100 - SystemIdle >= 50;
) AS ShreddedCpuXml
) AS OsCpu
WHERE CpuUsage >= 50;

/* CPU Utilization - CheckID 23 */
IF (@Debug = 1)
Expand All @@ -2423,7 +2443,8 @@ If one of them is a lead blocker, consider killing that query.'' AS HowToStopit,
WITH y
AS
(
SELECT CONVERT(VARCHAR(5), 100 - ca.c.value('.', 'INT')) AS system_idle,
/* See earlier comments about SystemIdle on Linux. */
SELECT CONVERT(VARCHAR(5), CASE WHEN @is_windows_operating_system = 1 THEN 100 - ca.c.value('.', 'INT') ELSE ca2.p.value('.', 'INT') END) AS cpu_usage,
CONVERT(VARCHAR(30), rb.event_date) AS event_date,
CONVERT(VARCHAR(8000), rb.record) AS record,
event_date as event_date_raw
Expand All @@ -2436,19 +2457,20 @@ If one of them is a lead blocker, consider killing that query.'' AS HowToStopit,
WHERE dorb.ring_buffer_type = N'RING_BUFFER_SCHEDULER_MONITOR'
AND record LIKE '%<SystemHealth>%' ) AS rb
CROSS APPLY rb.record.nodes('/Record/SchedulerMonitorEvent/SystemHealth/SystemIdle') AS ca(c)
CROSS APPLY rb.record.nodes('/Record/SchedulerMonitorEvent/SystemHealth/ProcessUtilization') AS ca2(p)
)
INSERT INTO #BlitzFirstResults (CheckID, Priority, FindingsGroup, Finding, Details, DetailsInt, URL, HowToStopIt)
SELECT TOP 1
23,
250,
'Server Info',
'CPU Utilization',
y.system_idle + N'%. Ring buffer details: ' + CAST(y.record AS NVARCHAR(4000)),
y.system_idle ,
y.cpu_usage + N'%. Ring buffer details: ' + CAST(y.record AS NVARCHAR(4000)),
y.cpu_usage ,
'https://www.brentozar.com/go/cpu',
STUFF(( SELECT TOP 2147483647
CHAR(10) + CHAR(13)
+ y2.system_idle
+ y2.cpu_usage
+ '% ON '
+ y2.event_date
+ ' Ring buffer details: '
Expand Down Expand Up @@ -2479,7 +2501,12 @@ If one of them is a lead blocker, consider killing that query.'' AS HowToStopit,
AND record LIKE '%<SystemHealth>%'
ORDER BY timestamp DESC) AS rb
) AS y
WHERE 100 - (y.SQLUsage + y.SystemIdle) >= 25;
WHERE 100 - (y.SQLUsage + y.SystemIdle) >= 25
/* SystemIdle is always 0 on Linux, as described earlier.
We therefore cannot distinguish between a totally idle Linux server and
a Linux server where SQL Server is being crushed by other CPU-heavy processes.
We therefore disable this check on Linux. */
AND @is_windows_operating_system = 1;

END; /* IF @Seconds < 30 */

Expand Down Expand Up @@ -3593,18 +3620,24 @@ If one of them is a lead blocker, consider killing that query.'' AS HowToStopit,
END

INSERT INTO #BlitzFirstResults (CheckID, Priority, FindingsGroup, Finding, Details, DetailsInt, URL)
SELECT 24, 50, 'Server Performance', 'High CPU Utilization', CAST(100 - SystemIdle AS NVARCHAR(20)) + N'%. Ring buffer details: ' + CAST(record AS NVARCHAR(4000)), 100 - SystemIdle, 'https://www.brentozar.com/go/cpu'
SELECT 24, 50, 'Server Performance', 'High CPU Utilization', CAST(CpuUsage AS NVARCHAR(20)) + N'%. Ring buffer details: ' + CAST(record AS NVARCHAR(4000)), CpuUsage, 'https://www.brentozar.com/go/cpu'
FROM (
SELECT record,
CASE WHEN @is_windows_operating_system = 1 THEN 100 - SystemIdle ELSE ProcessUtilization END AS CpuUsage
FROM (
SELECT record,
record.value('(./Record/SchedulerMonitorEvent/SystemHealth/SystemIdle)[1]', 'int') AS SystemIdle
record.value('(./Record/SchedulerMonitorEvent/SystemHealth/SystemIdle)[1]', 'int') AS SystemIdle,
/* See earlier comments about SystemIdle on Linux. */
record.value('(./Record/SchedulerMonitorEvent/SystemHealth/ProcessUtilization)[1]', 'int') AS ProcessUtilization
FROM (
SELECT TOP 1 CONVERT(XML, record) AS record
FROM sys.dm_os_ring_buffers
WHERE ring_buffer_type = N'RING_BUFFER_SCHEDULER_MONITOR'
AND record LIKE '%<SystemHealth>%'
ORDER BY timestamp DESC) AS rb
) AS y
WHERE 100 - SystemIdle >= 50;
) AS ShreddedCpuXml
) AS OsCpu
WHERE CpuUsage >= 50;

/* Server Performance - CPU Utilization CheckID 23 */
IF (@Debug = 1)
Expand All @@ -3613,17 +3646,23 @@ If one of them is a lead blocker, consider killing that query.'' AS HowToStopit,
END

INSERT INTO #BlitzFirstResults (CheckID, Priority, FindingsGroup, Finding, Details, DetailsInt, URL)
SELECT 23, 250, 'Server Info', 'CPU Utilization', CAST(100 - SystemIdle AS NVARCHAR(20)) + N'%. Ring buffer details: ' + CAST(record AS NVARCHAR(4000)), 100 - SystemIdle, 'https://www.brentozar.com/go/cpu'
SELECT 23, 250, 'Server Info', 'CPU Utilization', CAST(CpuUsage AS NVARCHAR(20)) + N'%. Ring buffer details: ' + CAST(record AS NVARCHAR(4000)), CpuUsage, 'https://www.brentozar.com/go/cpu'
FROM (
SELECT record,
CASE WHEN @is_windows_operating_system = 1 THEN 100 - SystemIdle ELSE ProcessUtilization END AS CpuUsage
FROM (
SELECT record,
record.value('(./Record/SchedulerMonitorEvent/SystemHealth/SystemIdle)[1]', 'int') AS SystemIdle
record.value('(./Record/SchedulerMonitorEvent/SystemHealth/SystemIdle)[1]', 'int') AS SystemIdle,
/* See earlier comments about SystemIdle on Linux. */
record.value('(./Record/SchedulerMonitorEvent/SystemHealth/ProcessUtilization)[1]', 'int') AS ProcessUtilization
FROM (
SELECT TOP 1 CONVERT(XML, record) AS record
FROM sys.dm_os_ring_buffers
WHERE ring_buffer_type = N'RING_BUFFER_SCHEDULER_MONITOR'
AND record LIKE '%<SystemHealth>%'
ORDER BY timestamp DESC) AS rb
) AS y;
) AS ShreddedCpuXml
) AS OsCpu;

END; /* IF @Seconds >= 30 */

Expand Down
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