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authorLinus Torvalds2021-11-10 16:10:47 -0800
committerLinus Torvalds2021-11-10 16:10:47 -0800
commita41b74451b35f7a6529689760eb8c05241feecbc (patch)
tree3a5985890703e5ef36a698a3284ddecb6d1086c8 /drivers
parent6752de1aebee8e73ee9cc31263407fdf0e29c274 (diff)
parent61bc346ce64a3864ac55f5d18bdc1572cda4fb18 (diff)
Merge tag 'kernel.sys.v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux
Pull prctl updates from Christian Brauner: "This contains the missing prctl uapi pieces for PR_SCHED_CORE. In order to activate core scheduling the caller is expected to specify the scope of the new core scheduling domain. For example, passing 2 in the 4th argument of prctl(PR_SCHED_CORE, PR_SCHED_CORE_CREATE, <pid>, 2, 0); would indicate that the new core scheduling domain encompasses all tasks in the process group of <pid>. Specifying 0 would only create a core scheduling domain for the thread identified by <pid> and 2 would encompass the whole thread-group of <pid>. Note, the values 0, 1, and 2 correspond to PIDTYPE_PID, PIDTYPE_TGID, and PIDTYPE_PGID. A first version tried to expose those values directly to which I objected because: - PIDTYPE_* is an enum that is kernel internal which we should not expose to userspace directly. - PIDTYPE_* indicates what a given struct pid is used for it doesn't express a scope. But what the 4th argument of PR_SCHED_CORE prctl() expresses is the scope of the operation, i.e. the scope of the core scheduling domain at creation time. So Eugene's patch now simply introduces three new defines PR_SCHED_CORE_SCOPE_THREAD, PR_SCHED_CORE_SCOPE_THREAD_GROUP, and PR_SCHED_CORE_SCOPE_PROCESS_GROUP. They simply express what happens. This has been on the mailing list for quite a while with all relevant scheduler folks Cced. I announced multiple times that I'd pick this up if I don't see or her anyone else doing it. None of this touches proper scheduler code but only concerns uapi so I think this is fine. With core scheduling being quite common now for vm managers (e.g. moving individual vcpu threads into their own core scheduling domain) and container managers (e.g. moving the init process into its own core scheduling domain and letting all created children inherit it) having to rely on raw numbers passed as the 4th argument in prctl() is a bit annoying and everyone is starting to come up with their own defines" * tag 'kernel.sys.v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux: uapi/linux/prctl: provide macro definitions for the PR_SCHED_CORE type argument
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