On Tue, Aug 28, 2018 at 01:11:11PM -0700, Randy Dunlap wrote:

On 08/28/2018 10:22 AM, Johannes Weiner wrote:

quoted

diff --git a/Documentation/accounting/psi.txt b/Documentation/accounting/psi.txt
new file mode 100644
index 000000000000..51e7ef14142e
--- /dev/null
+++ b/Documentation/accounting/psi.txt

@@ -0,0 +1,64 @@
+================================
+PSI - Pressure Stall Information
+================================
+
+:Date: April, 2018
+:Author: Johannes Weiner <hannes@cmpxchg.org>
+
+When CPU, memory or IO devices are contended, workloads experience
+latency spikes, throughput losses, and run the risk of OOM kills.
+
+Without an accurate measure of such contention, users are forced to
+either play it safe and under-utilize their hardware resources, or
+roll the dice and frequently suffer the disruptions resulting from
+excessive overcommit.
+
+The psi feature identifies and quantifies the disruptions caused by
+such resource crunches and the time impact it has on complex workloads
+or even entire systems.
+
+Having an accurate measure of productivity losses caused by resource
+scarcity aids users in sizing workloads to hardware--or provisioning
+hardware according to workload demand.
+
+As psi aggregates this information in realtime, systems can be managed
+dynamically using techniques such as load shedding, migrating jobs to
+other systems or data centers, or strategically pausing or killing low
+priority or restartable batch jobs.
+
+This allows maximizing hardware utilization without sacrificing
+workload health or risking major disruptions such as OOM kills.
+
+Pressure interface
+==================
+
+Pressure information for each resource is exported through the
+respective file in /proc/pressure/ -- cpu, memory, and io.
+

Hi,

quoted

+In both cases, the format for CPU is as such:

I don't see what "In both cases" refers to here.  It seems that you could
just remove it.

You're right, that must be a left-over from when I described CPU
separately; "both cases" referred to memory and IO which have
identical formats. It needs to be removed:

diff --git a/Documentation/accounting/psi.txt b/Documentation/accounting/psi.txt
index e051810d5127..b8ca28b60215 100644
--- a/Documentation/accounting/psi.txt
+++ b/Documentation/accounting/psi.txt

@@ -35,7 +35,7 @@ Pressure interface
 Pressure information for each resource is exported through the
 respective file in /proc/pressure/ -- cpu, memory, and io.
 
-In both cases, the format for CPU is as such:
+The format for CPU is as such:
 
 some avg10=0.00 avg60=0.00 avg300=0.00 total=0