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linux: clarify pids cgroup settings #1279

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linux: clarify pids cgroup settings #1279

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4 changes: 3 additions & 1 deletion config-linux.md
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Expand Up @@ -564,7 +564,9 @@ For more information, see the kernel cgroups documentation about [pids][cgroup-v

The following parameters can be specified to set up the controller:

* **`limit`** *(int64, REQUIRED)* - specifies the maximum number of tasks in the cgroup
* **`limit`** *(int64, REQUIRED)* - specifies the maximum number of tasks in the cgroup, with `-1` indicating no limit (`max`).

> Note: Even though it superficially seems redundant, `0` is a valid limit value for the `pids` cgroup controller and SHOULD NOT be treated as a special value.
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> Note: Even though it superficially seems redundant, `0` is a valid limit value for the `pids` cgroup controller and SHOULD NOT be treated as a special value.
> Note: Even though it superficially seems redundant, `0` is a valid limit value for the `pids` cgroup controller from kernel's perspective, and SHOULD NOT be treated as "no limit". An implementation may reject `0`.


#### Example

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2 changes: 1 addition & 1 deletion specs-go/config.go
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Expand Up @@ -430,7 +430,7 @@ type LinuxCPU struct {
// LinuxPids for Linux cgroup 'pids' resource management (Linux 4.3)
type LinuxPids struct {
// Maximum number of PIDs. Default is "no limit".
Limit int64 `json:"limit"`
Limit *int64 `json:"limit,omitempty"`
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With this changed to pointer, should that mean that it's no longer REQUIRED? (i.e., either setting -1 or omitting means "no limit"?

I wonder how it originally was intended; i.e., if 0 (or "not set", because of Golang's defaults), meaning inherit whatever defaults are present.

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Yeah, the intention is for it to be the same as most/all of the other cgroup settings we have. As I mentioned in the commit description, we ended up in this situation because of a bunch of unfortunate coincidences and this should correct the situation to be more in line with what most people would expect.

}

// LinuxNetwork identification and priority configuration
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