On Tue, Aug 28, 2018 at 01:11:11PM -0700, Randy Dunlap wrote: > On 08/28/2018 10:22 AM, Johannes Weiner wrote: > > 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@xxxxxxxxxxx> > > + > > +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, > > > +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
