Merge pull request #630 from xiaochenshen/rdt-cat-resctrl-cgroup-v1
specs-go/config: add Intel RDT/CAT Linux support
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Mrunal Patel
GitHub
commit
76159da8ca
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@ -476,6 +476,91 @@ The following parameters can be specified to setup the controller:
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}
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```
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## <a name="configLinuxIntelRdt" />IntelRdt
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Intel platforms with new Xeon CPU support Intel Resource Director Technology
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(RDT). Cache Allocation Technology (CAT) is a sub-feature of RDT, which
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currently supports L3 cache resource allocation.
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This feature provides a way for the software to restrict cache allocation to a
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defined 'subset' of L3 cache which may be overlapping with other 'subsets'.
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The different subsets are identified by class of service (CLOS) and each CLOS
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has a capacity bitmask (CBM).
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In Linux kernel, it is exposed via "resource control" filesystem, which is a
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"cgroup-like" interface.
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Comparing with cgroups, it has similar process management lifecycle and
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interfaces in a container. But unlike cgroups' hierarchy, it has single level
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filesystem layout.
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Intel RDT "resource control" filesystem hierarchy:
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```
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mount -t resctrl resctrl /sys/fs/resctrl
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tree /sys/fs/resctrl
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/sys/fs/resctrl/
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|-- info
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| |-- L3
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| |-- cbm_mask
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| |-- min_cbm_bits
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| |-- num_closids
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|-- cpus
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|-- schemata
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|-- tasks
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|-- <container_id>
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|-- cpus
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|-- schemata
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|-- tasks
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```
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For containers, we can make use of `tasks` and `schemata` configuration for
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L3 cache resource constraints if hardware and kernel support Intel RDT/CAT.
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The file `tasks` has a list of tasks that belongs to this group (e.g.,
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<container_id>" group). Tasks can be added to a group by writing the task ID
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to the "tasks" file (which will automatically remove them from the previous
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group to which they belonged). New tasks created by fork(2) and clone(2) are
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added to the same group as their parent. If a pid is not in any sub group, it
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is in root group.
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The file `schemata` has allocation masks/values for L3 cache on each socket,
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which contains L3 cache id and capacity bitmask (CBM).
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```
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Format: "L3:<cache_id0>=<cbm0>;<cache_id1>=<cbm1>;..."
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```
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For example, on a two-socket machine, L3's schema line could be `L3:0=ff;1=c0`
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Which means L3 cache id 0's CBM is 0xff, and L3 cache id 1's CBM is 0xc0.
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The valid L3 cache CBM is a *contiguous bits set* and number of bits that can
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be set is less than the max bit. The max bits in the CBM is varied among
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supported Intel Xeon platforms. In Intel RDT "resource control" filesystem
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layout, the CBM in a group should be a subset of the CBM in root. Kernel will
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check if it is valid when writing. e.g., 0xfffff in root indicates the max bits
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of CBM is 20 bits, which mapping to entire L3 cache capacity. Some valid CBM
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values to set in a group: 0xf, 0xf0, 0x3ff, 0x1f00 and etc.
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**`intelRdt`** (object, OPTIONAL) represents the L3 cache resource constraints in Intel Xeon platforms.
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For more information, see [Intel RDT/CAT kernel interface][intel-rdt-cat-kernel-interface].
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The following parameters can be specified for the container:
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* **`l3CacheSchema`** *(string, OPTIONAL)* - specifies the schema for L3 cache id and capacity bitmask (CBM)
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###### Example
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```json
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There are two L3 caches in the two-socket machine, the default CBM is 0xfffff
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and the max CBM length is 20 bits. This configuration assigns 4/5 of L3 cache
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id 0 and the whole L3 cache id 1 for the container:
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"linux": {
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"intelRdt": {
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"l3CacheSchema": "L3:0=ffff0;1=fffff"
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}
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}
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```
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## <a name="configLinuxSysctl" />Sysctl
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**`sysctl`** (object, OPTIONAL) allows kernel parameters to be modified at runtime for the container.
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@ -638,3 +723,4 @@ The values MUST be absolute paths in the [container namespace][container-namespa
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[tty.4]: http://man7.org/linux/man-pages/man4/tty.4.html
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[zero.4]: http://man7.org/linux/man-pages/man4/zero.4.html
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[user-namespaces]: http://man7.org/linux/man-pages/man7/user_namespaces.7.html
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[intel-rdt-cat-kernel-interface]: https://www.kernel.org/doc/Documentation/x86/intel_rdt_ui.txt
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@ -169,6 +169,9 @@ type Linux struct {
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ReadonlyPaths []string `json:"readonlyPaths,omitempty"`
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// MountLabel specifies the selinux context for the mounts in the container.
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MountLabel string `json:"mountLabel,omitempty"`
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// IntelRdt contains Intel Resource Director Technology (RDT) information
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// for handling resource constraints (e.g., L3 cache) for the container
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IntelRdt *LinuxIntelRdt `json:"intelRdt,omitempty"`
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}
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// LinuxNamespace is the configuration for a Linux namespace
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@ -550,3 +553,11 @@ type LinuxSyscall struct {
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Action LinuxSeccompAction `json:"action"`
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Args []LinuxSeccompArg `json:"args"`
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}
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// LinuxIntelRdt has container runtime resource constraints
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// for Intel RDT/CAT which introduced in Linux 4.10 kernel
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type LinuxIntelRdt struct {
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// The schema for L3 cache id and capacity bitmask (CBM)
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// Format: "L3:<cache_id0>=<cbm0>;<cache_id1>=<cbm1>;..."
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L3CacheSchema string `json:"l3CacheSchema,omitempty"`
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}
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