Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1622826

Re: [PATCH v2] sched: Have do_idle() call __schedule() without enabling preemption

From Peter Zijlstra <peterz@infradead.org>
Newsgroups linux.kernel
Subject Re: [PATCH v2] sched: Have do_idle() call __schedule() without enabling preemption
Date 2017-04-13 10:50 +0200
Message-ID <tvIBX-oq-7@gated-at.bofh.it> (permalink)
References <tvvbH-7UV-13@gated-at.bofh.it>
Organization linux.* mail to news gateway

Show all headers | View raw

On Wed, Apr 12, 2017 at 02:27:44PM -0400, Steven Rostedt wrote:
> + * schedule_idle() is similar to schedule_preempt_disable() except
> + * that it never enables preemption.

That's not right. The primary distinction is that it doesn't call
sched_submit_work().

And because that function is a no-op for the idle thread, the idle
thread can do without calling that and therefore avoid the preemption
window.

You also need a few words about fake idle threads, search play_idle()
callers.

You could also make schedule_idle() more robust by adding a WARN for the
blk_schedule_flush_plug() condition.


You Changelog is still entirely long and rambling but fails to mention
the fundamental important stuff :-(

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCH v2] sched: Have do_idle() call __schedule() without   enabling preemption Steven Rostedt <rostedt@goodmis.org> - 2017-04-12 20:30 +0200
  Re: [PATCH v2] sched: Have do_idle() call __schedule() without   enabling preemption Steven Rostedt <rostedt@goodmis.org> - 2017-04-12 20:40 +0200
  Re: [PATCH v2] sched: Have do_idle() call __schedule() without   enabling preemption "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-04-13 01:50 +0200
    Re: [PATCH v2] sched: Have do_idle() call __schedule() without   enabling preemption Steven Rostedt <rostedt@goodmis.org> - 2017-04-13 02:50 +0200
      Re: [PATCH v2] sched: Have do_idle() call __schedule() without  enabling preemption "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-04-13 03:00 +0200
  Re: [PATCH v2] sched: Have do_idle() call __schedule() without  enabling preemption Peter Zijlstra <peterz@infradead.org> - 2017-04-13 10:50 +0200
    Re: [PATCH v2] sched: Have do_idle() call __schedule() without  enabling preemption Steven Rostedt <rostedt@goodmis.org> - 2017-04-13 15:50 +0200
      Re: [PATCH v2] sched: Have do_idle() call __schedule() without  enabling preemption Peter Zijlstra <peterz@infradead.org> - 2017-04-13 16:40 +0200
        Re: [PATCH v2] sched: Have do_idle() call __schedule() without  enabling preemption Steven Rostedt <rostedt@goodmis.org> - 2017-04-13 17:00 +0200

csiph-web