[PATCH v4 0/2] cgroups: implement moving a threadgroup's threads atomically with cgroup.procs
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From: Ben Blum on 30 Jul 2010 20:00 This patch series is a revision of http://lkml.org/lkml/2010/6/25/11 . This patch series implements a write function for the 'cgroup.procs' per-cgroup file, which enables atomic movement of multithreaded applications between cgroups. Writing the thread-ID of any thread in a threadgroup to a cgroup's procs file causes all threads in the group to be moved to that cgroup safely with respect to threads forking/exiting. (Possible usage scenario: If running a multithreaded build system that sucks up system resources, this lets you restrict it all at once into a new cgroup to keep it under control.) Example: Suppose pid 31337 clones new threads 31338 and 31339. # cat /dev/cgroup/tasks .... 31337 31338 31339 # mkdir /dev/cgroup/foo # echo 31337 > /dev/cgroup/foo/cgroup.procs # cat /dev/cgroup/foo/tasks 31337 31338 31339 A new lock, called threadgroup_fork_lock and living in signal_struct, is introduced to ensure atomicity when moving threads between cgroups. It's taken for writing during the operation, and taking for reading in fork() around the calls to cgroup_fork() and cgroup_post_fork(). I put calls to down_read/up_read directly in copy_process(), since new inline functions seemed like overkill. -- Ben --- Documentation/cgroups/cgroups.txt | 13 - include/linux/init_task.h | 9 include/linux/sched.h | 10 kernel/cgroup.c | 426 +++++++++++++++++++++++++++++++++----- kernel/cgroup_freezer.c | 4 kernel/cpuset.c | 4 kernel/fork.c | 16 + kernel/ns_cgroup.c | 4 kernel/sched.c | 4 9 files changed, 440 insertions(+), 50 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |