// Copyright 2019 The Prometheus Authors // Licensed under the Apache License, Version 2.0 (the "License"); // you may not use this file except in compliance with the License. // You may obtain a copy of the License at // // http://www.apache.org/licenses/LICENSE-2.0 // // Unless required by applicable law or agreed to in writing, software // distributed under the License is distributed on an "AS IS" BASIS, // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. // See the License for the specific language governing permissions and // limitations under the License. package procfs // The PSI / pressure interface is described at // https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/accounting/psi.txt // Each resource (cpu, io, memory, ...) is exposed as a single file. // Each file may contain up to two lines, one for "some" pressure and one for "full" pressure. // Each line contains several averages (over n seconds) and a total in µs. // // Example io pressure file: // > some avg10=0.06 avg60=0.21 avg300=0.99 total=8537362 // > full avg10=0.00 avg60=0.13 avg300=0.96 total=8183134 import ( "bufio" "bytes" "fmt" "io" "strings" "github.com/prometheus/procfs/internal/util" ) const lineFormat = "avg10=%f avg60=%f avg300=%f total=%d" // PSILine is a single line of values as returned by `/proc/pressure/*`. // // The Avg entries are averages over n seconds, as a percentage. // The Total line is in microseconds. type PSILine struct { Avg10 float64 Avg60 float64 Avg300 float64 Total uint64 } // PSIStats represent pressure stall information from /proc/pressure/* // // "Some" indicates the share of time in which at least some tasks are stalled. // "Full" indicates the share of time in which all non-idle tasks are stalled simultaneously. type PSIStats struct { Some *PSILine Full *PSILine } // PSIStatsForResource reads pressure stall information for the specified // resource from /proc/pressure/<resource>. At time of writing this can be // either "cpu", "memory" or "io". func (fs FS) PSIStatsForResource(resource string) (PSIStats, error) { data, err := util.ReadFileNoStat(fs.proc.Path(fmt.Sprintf("%s/%s", "pressure", resource))) if err != nil { return PSIStats{}, fmt.Errorf("%w: psi_stats: unavailable for %q: %w", ErrFileRead, resource, err) } return parsePSIStats(bytes.NewReader(data)) } // parsePSIStats parses the specified file for pressure stall information. func parsePSIStats(r io.Reader) (PSIStats, error) { psiStats := PSIStats{} scanner := bufio.NewScanner(r) for scanner.Scan() { l := scanner.Text() prefix := strings.Split(l, " ")[0] switch prefix { case "some": psi := PSILine{} _, err := fmt.Sscanf(l, fmt.Sprintf("some %s", lineFormat), &psi.Avg10, &psi.Avg60, &psi.Avg300, &psi.Total) if err != nil { return PSIStats{}, err } psiStats.Some = &psi case "full": psi := PSILine{} _, err := fmt.Sscanf(l, fmt.Sprintf("full %s", lineFormat), &psi.Avg10, &psi.Avg60, &psi.Avg300, &psi.Total) if err != nil { return PSIStats{}, err } psiStats.Full = &psi default: // If we encounter a line with an unknown prefix, ignore it and move on // Should new measurement types be added in the future we'll simply ignore them instead // of erroring on retrieval continue } } return psiStats, nil }