Initially, this was copied over from libcontainer/cgroups, where it made
sense as for cgroup v1 we have multiple controllers and mount points.
Here, we only have a single mount, so there's no need for the whole
type.
Replace all that with a simple error (which is currently internal since
the only user is our own test case).
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
1. These tests can't be run in parallel since they do check
a global variable (mbaScEnabled).
2. findIntelRdtMountpointDir() relies on mbaScEnabled to be initially
set to the default value (false) and this the test fails if run
more than once:
> go test -count 2
> ...
> intelrdt_test.go:243: expected mbaScEnabled=false, got true
> --- FAIL: TestFindIntelRdtMountpointDir/Valid_mountinfo_with_MBA_Software_Controller_disabled (0.00s)
Fixes: 2c70d2384
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
MBA Software Controller feature is introduced in Linux kernel v4.18.
It is a software enhancement to mitigate some limitations in MBA which
describes in kernel documentation. It also makes the interface more user
friendly - we could specify memory bandwidth in "MBps" (Mega Bytes per
second) as well as in "percentages".
The kernel underneath would use a software feedback mechanism or a
"Software Controller" which reads the actual bandwidth using MBM
counters and adjust the memory bandwidth percentages to ensure:
"actual memory bandwidth < user specified memory bandwidth".
We could enable this feature through mount option "-o mba_MBps":
mount -t resctrl resctrl -o mba_MBps /sys/fs/resctrl
In runc, we handle both memory bandwidth schemata in unified format:
"MB:<cache_id0>=bandwidth0;<cache_id1>=bandwidth1;..."
The unit of memory bandwidth is specified in "percentages" by default,
and in "MBps" if MBA Software Controller is enabled.
For more information about Intel RDT and MBA Software Controller:
https://www.kernel.org/doc/Documentation/x86/intel_rdt_ui.txt
Signed-off-by: Xiaochen Shen <xiaochen.shen@intel.com>
This is the follow-up PR of #1279 to fix remaining issues:
Use init() to avoid race condition in IsIntelRdtEnabled().
Add also rename some variables and functions.
Signed-off-by: Xiaochen Shen <xiaochen.shen@intel.com>
