As stated I think this idea is a non-starter. There is a real problem that there are applications that have a legitimate need to know what cpu resources are available for them to use and we don't have a good interfaces for them to request that information. I think MESOS solved this by passing a MAX_CPUS environment variable, and at least the JVM was modified to use that variable. That said as situations can be a bit more dynamic and fluid having something where an application can look and see what resources are available from it's view of the world seems reasonable. AKA we need something so applications can stop conflating physical cpu resources that are available with cpu resources that are allowed to be used in an application. This might be as simple as implementing a /proc/self/cpus_available file. Without the will to go through find existing open source applications that care and update them so that they will use the new interface I don't think anything will really happen. The problem I see with changing existing interfaces that describe the hardware is that the definition becomes unclear and so different applications can legitimately expect different things, and it would become impossible to implement what is needed correctly. The problem I see with using cgroup interfaces is that they are not targeted at end user applications and but rather are targeted at the problem of controlling access to a resource. Using them report what is available again gets you into the multiple master problem. Especially as cgroups may not be the only thing in the system controlling access to your resource. So I really think the only good solution that people won't mind is to go through the applications figure out what information is legitimately needed from an application perspective, and build an interface tailored for applications to get that information. Then applications can be updated to use the new interface, and as the implementation of the system changes the implementation in the kernel can be updated to keep the applications working. Eric
