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[GR-44245] Obsolete UseContainerCpuShares and PreferContainerQuotaForCPUCount flags. #6051

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Merged
merged 1 commit into from
Feb 23, 2023
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[GR-44245] Obsolete UseContainerCpuShares and PreferContainerQuotaForCPUCount flags. #6051

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70 changes: 5 additions & 65 deletions substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/Containers.java
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Original file line number Diff line number Diff line change
Expand Up @@ -24,10 +24,7 @@
*/
package com.oracle.svm.core;

import static com.oracle.svm.core.Containers.Options.PreferContainerQuotaForCPUCount;
import static com.oracle.svm.core.Containers.Options.UseContainerCpuShares;
import static com.oracle.svm.core.Containers.Options.UseContainerSupport;
import static com.oracle.svm.core.option.RuntimeOptionKey.RuntimeOptionKeyFlag.RelevantForCompilationIsolates;

import org.graalvm.compiler.options.Option;
import org.graalvm.compiler.serviceprovider.JavaVersionUtil;
Expand All @@ -40,7 +37,6 @@
import com.oracle.svm.core.feature.InternalFeature;
import com.oracle.svm.core.jdk.Jvm;
import com.oracle.svm.core.option.HostedOptionKey;
import com.oracle.svm.core.option.RuntimeOptionKey;
import com.oracle.svm.core.util.VMError;

/**
Expand All @@ -53,45 +49,17 @@ public class Containers {
public static class Options {
@Option(help = "Enable detection and runtime container configuration support.")//
public static final HostedOptionKey<Boolean> UseContainerSupport = new HostedOptionKey<>(true);

@Option(help = "Include CPU shares in the CPU availability calculation.")//
public static final HostedOptionKey<Boolean> UseContainerCpuShares = new HostedOptionKey<>(false);

@Option(help = "Calculate the container CPU availability based on the value of quotas (if set), when true. " +
"Otherwise, use the CPU shares value, provided it is less than quota.")//
public static final RuntimeOptionKey<Boolean> PreferContainerQuotaForCPUCount = new RuntimeOptionKey<>(true, RelevantForCompilationIsolates);
}

/** Sentinel used when the value is unknown. */
public static final int UNKNOWN = -1;

/*-
* PER_CPU_SHARES has been set to 1024 because CPU shares' quota
* is commonly used in cloud frameworks like Kubernetes[1],
* AWS[2] and Mesos[3] in a similar way. They spawn containers with
* --cpu-shares option values scaled by PER_CPU_SHARES. Thus, we do
* the inverse for determining the number of possible available
* CPUs to the JVM inside a container. See JDK-8216366.
*
* [1] https://kubernetes.io/docs/concepts/configuration/manage-compute-resources-container/#meaning-of-cpu
* In particular:
* When using Docker:
* The spec.containers[].resources.requests.cpu is converted to its core value, which is potentially
* fractional, and multiplied by 1024. The greater of this number or 2 is used as the value of the
* --cpu-shares flag in the docker run command.
* [2] https://docs.aws.amazon.com/AmazonECS/latest/APIReference/API_ContainerDefinition.html
* [3] https://github.com/apache/mesos/blob/3478e344fb77d931f6122980c6e94cd3913c441d/src/docker/docker.cpp#L648
* https://github.com/apache/mesos/blob/3478e344fb77d931f6122980c6e94cd3913c441d/src/slave/containerizer/mesos/isolators/cgroups/constants.hpp#L30
*/
private static final int PER_CPU_SHARES = 1024;

/**
* Calculates an appropriate number of active processors for the VM to use. The calculation is
* based on these three inputs:
* based on these two inputs:
* <ul>
* <li>cpu affinity
* <li>cpu quota & cpu period
* <li>cpu shares
* </ul>
*
* @return number of CPUs
Expand All @@ -105,21 +73,12 @@ public static int activeProcessorCount() {
* If user specified a quota (quota != -1), calculate the number of
* required CPUs by dividing quota by period.
*
* If shares are in effect (shares != -1), calculate the number
* of CPUs required for the shares by dividing the share value
* by PER_CPU_SHARES.
*
* All results of division are rounded up to the next whole number.
*
* If neither shares nor quotas have been specified, return the
* If quotas have not been specified, return the
* number of active processors in the system.
*
* If both shares and quotas have been specified, the results are
* based on the flag PreferContainerQuotaForCPUCount. If true,
* return the quota value. If false return the smallest value
* between shares and quotas.
*
* If shares and/or quotas have been specified, the resulting number
* If quotas have been specified, the resulting number
* returned will never exceed the number of active processors.
*/
int cpuCount = Jvm.JVM_ActiveProcessorCount();
Expand All @@ -131,33 +90,14 @@ public static int activeProcessorCount() {
long quota = info.getCpuQuota();
long period = info.getCpuPeriod();

/*-
* It's not a good idea to use CPU shares to limit the number
* of CPUs used by the VM. See JDK-8281181.
*/
long shares = UseContainerCpuShares.getValue() ? info.getCpuShares() : -1;

int quotaCount = 0;
if (quota > -1 && period > 0) {
quotaCount = (int) Math.ceil(((double) quota) / period);
}

int shareCount = 0;
if (shares > -1) {
shareCount = (int) Math.ceil(((double) shares) / PER_CPU_SHARES);
}

if (quotaCount != 0 && shareCount != 0) {
/* Both shares and quotas are specified. */
if (PreferContainerQuotaForCPUCount.getValue()) {
limitCount = quotaCount;
} else {
limitCount = Math.min(quotaCount, shareCount);
}
} else if (quotaCount != 0) {
/* Use quotas. */
if (quotaCount != 0) {
limitCount = quotaCount;
} else if (shareCount != 0) {
limitCount = shareCount;
}
}
}
Expand Down