[IVI] 15.1.2 system stability optimization (lmkd Ⅱ) psi pressure stall information

Write it at the front

To better identify resource conflicts , And easy to manage Facebook Data center system overload problem .Facebook The kernel team developed PSI Mechanism .PSI It's a kind of passing Linux The kernel gets memory 、CPU and I/O A new method of utilization index .

Next, let's briefly introduce PSI And how to use it , However, this article does not start from Android From the perspective of , More purely based on PSI Own research .

One 、 summary

PSI For the first time, it provides a method specification to observe the increasing resource pressure with development , This method uses a new pressure index to monitor the three resources of the system -Memory、CPU、IO.

These stress indicators are consistent with CGroup2 Associated with other kernel or user space tools described below , To help you monitor and respond to resource constraints during development , Such as stopping or killing unimportant processes , Reclaim system memory, etc .

PSI The state is like a barometer , Provide warnings when resources are tight , More importantly, under the trend of resource tension , Take more initiative , More sophisticated resource management .

You can refer to https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/accounting/psi.txt For more information .

Two 、 precondition

Linux kernel 4.20+ Version introduced PSI, So I want to enable PSI function , You need to configure the following options when compiling the kernel ：

CONFIG_PS