Subject: [RFC v5 PATCH 0/8] CFS Hard limits - v5
Date: Tuesday 5th January 2010 07:57:03 UTC (over 6 years ago)
Hi, This is the v5 post of CFS hard limits. In this patchset, I have pulled out bandwidth and runtime handling code from RT into sched.c so that the same code can be used by CFS hard limits. Also I have addressed the review comments given by Peter Zijlstra for v4. Changes ------- RFC v5: - Make RT bandwidth and runtime handing code generic and use it in CFS also. - Remove the *_locked() version from sched_fair.c by simplifying the locking. This fixes the unlock imbalance bug seen by Jarek Dylag who observed it while using CFS hard limits with Linux vserver. RFC v4: - http://lkml.org/lkml/2009/11/17/191 - Reclaim runtimes lent to other cpus when a cpu goes offline. (Kamalesh Babulal) - Fixed a few bugs. - Some cleanups. RFC v3: - http://lkml.org/lkml/2009/11/9/65 - Till v2, I was updating rq->nr_running when tasks go and come back on runqueue during throttling and unthrottling. Don't do this. - With the above change, quite a bit of code simplification is achieved. Runtime related fields of cfs_rq are now being protected by per cfs_rq lock instead of per rq lock. With this it looks more similar to rt. - Remove the control file cpu.cfs_hard_limit which enabled/disabled hard limits for groups. Now hard limits is enabled by having a non-zero runtime. - Don't explicitly prevent movement of tasks into throttled groups during load balancing as throttled entities are anyway prevented from being enqueued in enqueue_task_fair(). - Moved to 2.6.32-rc6 RFC v2: - http://lkml.org/lkml/2009/9/30/115 - Upgraded to 2.6.31. - Added CFS runtime borrowing. - New locking scheme The hard limit specific fields of cfs_rq (cfs_runtime, cfs_time and cfs_throttled) were being protected by rq->lock. This simple scheme will not work when runtime rebalancing is introduced where it will be required to look at these fields on other CPU's which requires us to acquire rq->lock of other CPUs. This will not be feasible from update_curr(). Hence introduce a separate lock (rq->runtime_lock) to protect these fields of all cfs_rq under it. - Handle the task wakeup in a throttled group correctly. - Make CFS_HARD_LIMITS dependent on CGROUP_SCHED (Thanks to Andrea Righi) RFC v1: - First version of the patches with minimal features was posted at http://lkml.org/lkml/2009/8/25/128 RFC v0: - The CFS hard limits proposal was first posted at http://lkml.org/lkml/2009/6/4/24 Patches description ------------------- This post has the following patches: 1/8 sched: Rename struct rt_bandwidth to sched_bandwidth 2/8 sched: Make rt bandwidth timer and runtime related code generic 3/8 sched: Bandwidth initialization for fair task groups 4/8 sched: Enforce hard limits by throttling 5/8 sched: Unthrottle the throttled tasks 6/8 sched: Add throttle time statistics to /proc/sched_debug 7/8 sched: CFS runtime borrowing 8/8 sched: Hard limits documentation Documentation/scheduler/sched-cfs-hard-limits.txt | 48 + include/linux/sched.h | 6 init/Kconfig | 13 kernel/sched.c | 591 +++++++++++++++++--- kernel/sched_debug.c | 23 kernel/sched_fair.c | 354 +++++++++++ kernel/sched_rt.c | 268 +-------- 7 files changed, 964 insertions(+), 339 deletions(-) Regards, Bharata.