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// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.vespa.hosted.node.admin.cgroup;
import ai.vespa.validation.Validation;
import com.yahoo.vespa.hosted.node.admin.component.TaskContext;
import com.yahoo.vespa.hosted.node.admin.task.util.file.UnixPath;
import java.util.Map;
import java.util.Optional;
import java.util.logging.Logger;
import java.util.stream.Collectors;
import static java.lang.Integer.parseInt;
/**
* Represents a cgroup v2 IO controller, i.e. all io.* files.
*
* @author freva
*/
public class IoController {
private static final Logger logger = Logger.getLogger(IoController.class.getName());
private final Cgroup cgroup;
IoController(Cgroup cgroup) {
this.cgroup = cgroup;
}
public record Device(int major, int minor) implements Comparable<Device> {
public Device {
// https://www.halolinux.us/kernel-architecture/representation-of-major-and-minor-numbers.html
Validation.requireInRange(major, "device major", 0, 0xFFF);
Validation.requireInRange(minor, "device minor", 0, 0xFFFFF);
}
private String toFileContent() { return major + ":" + minor; }
private static Device fromString(String device) {
String[] parts = device.split(":");
return new Device(parseInt(parts[0]), parseInt(parts[1]));
}
@Override
public int compareTo(Device o) {
return major != o.major ? Integer.compare(major, o.major) : Integer.compare(minor, o.minor);
}
}
/**
* Defines max allowed IO:
* <ul>
* <li><b>rbps</b>: Read bytes per seconds</li>
* <li><b>riops</b>: Read IO operations per seconds</li>
* <li><b>wbps</b>: Write bytes per seconds</li>
* <li><b>wiops</b>: Write IO operations per seconds</li>
* </ul>.
*/
public record Max(Size rbps, Size wbps, Size riops, Size wiops) {
public static Max UNLIMITED = new Max(Size.max(), Size.max(), Size.max(), Size.max());
// Keys can be specified in any order, this is the order they are outputted in from io.max
// https://github.com/torvalds/linux/blob/c1a515d3c0270628df8ae5f5118ba859b85464a2/block/blk-throttle.c#L1541
private String toFileContent() { return "rbps=%s wbps=%s riops=%s wiops=%s".formatted(rbps, wbps, riops, wiops); }
public static Max fromString(String max) {
String[] parts = max.split(" ");
Size rbps = Size.max(), riops = Size.max(), wbps = Size.max(), wiops = Size.max();
for (String part : parts) {
if (part.isEmpty()) continue;
String[] kv = part.split("=");
if (kv.length != 2) throw new IllegalArgumentException("Invalid io.max format: " + max);
switch (kv[0]) {
case "rbps" -> rbps = Size.from(kv[1]);
case "riops" -> riops = Size.from(kv[1]);
case "wbps" -> wbps = Size.from(kv[1]);
case "wiops" -> wiops = Size.from(kv[1]);
default -> throw new IllegalArgumentException("Unknown key " + kv[0]);
}
}
return new Max(rbps, wbps, riops, wiops);
}
}
/**
* Returns the maximum allowed IO usage, by device, or empty if cgroup is not found.
*
* @see Max
*/
public Optional<Map<Device, Max>> readMax() {
return cgroup.readIfExists("io.max")
.map(content -> content
.lines()
.map(line -> {
String[] parts = line.strip().split(" ", 2);
return Map.entry(Device.fromString(parts[0]), Max.fromString(parts[1]));
})
.collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue)));
}
public boolean updateMax(TaskContext context, Device device, Max max) {
Max prevMax = readMax()
.map(maxByDevice -> maxByDevice.get(device))
.orElse(Max.UNLIMITED);
if (prevMax.equals(max)) return false;
UnixPath path = cgroup.unixPath().resolve("io.max");
context.recordSystemModification(logger, "Updating %s for device %s from '%s' to '%s'",
path, device.toFileContent(), prevMax.toFileContent(), max.toFileContent());
path.writeUtf8File(device.toFileContent() + ' ' + max.toFileContent() + '\n');
return true;
}
}
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