realtime:documentation:howto:tools:perf-smi-cost
Differences
This shows you the differences between two versions of the page.
| Both sides previous revision Previous revision | |||
|
realtime:documentation:howto:tools:perf-smi-cost [2018/08/21 15:40] ebugden Add warning about potential unreliability |
realtime:documentation:howto:tools:perf-smi-cost [2018/08/21 15:41] (current) ebugden Move warning above line |
||
|---|---|---|---|
| Line 2: | Line 2: | ||
| Perf's stat tool has an option that can measure the cost of [[realtime:documentation:howto:debugging:smi-latency:start|SMI]]s (--smi-cost) if the necessary MSRs exist on the CPU. This option calculates the percentage of cycles spent handling SMIs. If the --no-metric-only option is also used, the tool can be used to determine the average number of cycles taken to handle an SMI during the measurement period. These Perf options are available as of the 4.13 linux kernel and will only work on Intel x86 processors from after around 2008 (as of the Nehalem microarchitecture). | Perf's stat tool has an option that can measure the cost of [[realtime:documentation:howto:debugging:smi-latency:start|SMI]]s (--smi-cost) if the necessary MSRs exist on the CPU. This option calculates the percentage of cycles spent handling SMIs. If the --no-metric-only option is also used, the tool can be used to determine the average number of cycles taken to handle an SMI during the measurement period. These Perf options are available as of the 4.13 linux kernel and will only work on Intel x86 processors from after around 2008 (as of the Nehalem microarchitecture). | ||
| - | |||
| - | ---- | ||
| <WRAP center round important 60%> | <WRAP center round important 60%> | ||
| **Disclaimer:** The results from this tool may not be reliable. If the system enters an idle state while the tool is running and no SMIs occur, the counter values in the results appear to be inconsistent with their documentation in the Intel Software Development Manual. | **Disclaimer:** The results from this tool may not be reliable. If the system enters an idle state while the tool is running and no SMIs occur, the counter values in the results appear to be inconsistent with their documentation in the Intel Software Development Manual. | ||
| </WRAP> | </WRAP> | ||
| + | |||
| + | ---- | ||
| ===== Installation ===== | ===== Installation ===== | ||
realtime/documentation/howto/tools/perf-smi-cost.txt ยท Last modified: 2018/08/21 15:41 by ebugden
Page Tools
Except where otherwise noted, content on this wiki is licensed under the following license: CC Attribution-Noncommercial-Share Alike 4.0 International
