From: Tejun Heo <tj@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Daniel Jordan <daniel.m.jordan@oracle.com>,
Alexander Duyck <alexanderduyck@fb.com>,
Alex Williamson <alex.williamson@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Ben Segall <bsegall@google.com>,
Cornelia Huck <cohuck@redhat.com>,
Dan Williams <dan.j.williams@intel.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Herbert Xu <herbert@gondor.apana.org.au>,
Ingo Molnar <mingo@redhat.com>, Jason Gunthorpe <jgg@nvidia.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Josh Triplett <josh@joshtriplett.org>,
Michal Hocko <mhocko@suse.com>, Nico Pache <npache@redhat.com>,
Pasha Tatashin <pasha.tatashin@soleen.com>,
Steffen Klassert <steffen.klassert@secunet.com>,
Steve Sistare <steven.sistare@oracle.com>,
Tim Chen <tim.c.chen@linux.intel.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
linux-mm@kvack.org, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org
Subject: Re: [RFC 15/16] sched/fair: Account kthread runtime debt for CFS bandwidth
Date: Fri, 14 Jan 2022 06:38:09 -1000 [thread overview]
Message-ID: <YeGm8cbX6Krw+O3o@slm.duckdns.org> (raw)
In-Reply-To: <YeFE9j4Qynp9sNXS@hirez.programming.kicks-ass.net>
Hello,
On Fri, Jan 14, 2022 at 10:40:06AM +0100, Peter Zijlstra wrote:
> You could do a special case sched_move_task(), that takes a css argument
> instead of using the current task_css. Then for cgroups it looks like
> nothing changes, but the scheduler will DTRT and act like it is in the
> target cgroup. Then at the end, simply move it back to task_css.
>
> This obviously doesn't work for SoftIRQ accounting, but that is
> 'special' anyway. Softirq stuff is not otherwise under scheduler
> control and has preemption disabled.
So, if this particular use case doesn't fit the backcharge model (I'm not
sure yet). I'd much prefer it to maintain dynamic per-cgroup helper threads
than move tasks around dynamically. Nothing else is using migration this way
and we don't even need migration for seeding cgroups w/ CLONE_INTO_CGROUP.
In the future, this should allow further optimizations and likely
simplifications. It'd suck to have an odd exception usage.
Thanks.
--
tejun
next prev parent reply other threads:[~2022-01-14 16:38 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-06 0:46 [RFC 00/16] padata, vfio, sched: Multithreaded VFIO page pinning Daniel Jordan
2022-01-06 0:46 ` [RFC 01/16] padata: Remove __init from multithreading functions Daniel Jordan
2022-01-06 0:46 ` [RFC 02/16] padata: Return first error from a job Daniel Jordan
2022-01-06 0:46 ` [RFC 03/16] padata: Add undo support Daniel Jordan
2022-01-06 0:46 ` [RFC 04/16] padata: Detect deadlocks between main and helper threads Daniel Jordan
2022-01-06 0:46 ` [RFC 05/16] vfio/type1: Pass mm to vfio_pin_pages_remote() Daniel Jordan
2022-01-06 0:46 ` [RFC 06/16] vfio/type1: Refactor dma map removal Daniel Jordan
2022-01-06 0:46 ` [RFC 07/16] vfio/type1: Parallelize vfio_pin_map_dma() Daniel Jordan
2022-01-06 0:46 ` [RFC 08/16] vfio/type1: Cache locked_vm to ease mmap_lock contention Daniel Jordan
2022-01-06 0:53 ` Jason Gunthorpe
2022-01-06 1:17 ` Daniel Jordan
2022-01-06 12:34 ` Jason Gunthorpe
2022-01-06 21:05 ` Alex Williamson
2022-01-07 0:19 ` Jason Gunthorpe
2022-01-07 3:06 ` Daniel Jordan
2022-01-07 15:18 ` Jason Gunthorpe
2022-01-07 16:39 ` Daniel Jordan
2022-01-06 0:46 ` [RFC 09/16] padata: Use kthreads in do_multithreaded Daniel Jordan
2022-01-06 0:46 ` [RFC 10/16] padata: Helpers should respect main thread's CPU affinity Daniel Jordan
2022-01-06 0:46 ` [RFC 11/16] padata: Cap helpers started to online CPUs Daniel Jordan
2022-01-06 0:46 ` [RFC 12/16] sched, padata: Bound max threads with max_cfs_bandwidth_cpus() Daniel Jordan
2022-01-06 0:46 ` [RFC 13/16] padata: Run helper threads at MAX_NICE Daniel Jordan
2022-01-06 0:46 ` [RFC 14/16] padata: Nice helper threads one by one to prevent starvation Daniel Jordan
2022-01-06 0:46 ` [RFC 15/16] sched/fair: Account kthread runtime debt for CFS bandwidth Daniel Jordan
2022-01-11 11:58 ` Peter Zijlstra
2022-01-11 16:29 ` Daniel Jordan
2022-01-12 20:18 ` Tejun Heo
2022-01-13 21:08 ` Daniel Jordan
2022-01-13 21:11 ` Daniel Jordan
2022-01-14 9:31 ` Peter Zijlstra
2022-01-14 9:40 ` Peter Zijlstra
2022-01-14 16:38 ` Tejun Heo [this message]
2022-01-18 17:40 ` Daniel Jordan
2022-01-14 16:30 ` Tejun Heo
2022-01-18 17:32 ` Daniel Jordan
2022-01-06 0:46 ` [RFC 16/16] sched/fair: Consider kthread debt in cputime Daniel Jordan
2022-01-06 1:13 ` [RFC 00/16] padata, vfio, sched: Multithreaded VFIO page pinning Jason Gunthorpe
2022-01-07 3:03 ` Daniel Jordan
2022-01-07 17:12 ` Jason Gunthorpe
2022-01-10 22:27 ` Daniel Jordan
2022-01-11 0:17 ` Jason Gunthorpe
2022-01-11 16:20 ` Daniel Jordan
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