Re: [patch 2/3] timers: do not raise softirq unconditionally (spinlockless version)

2019-06-11 Thread Anna-Maria Gleixner
On Fri, 31 May 2019, Anna-Maria Gleixner wrote: [...] > I will think about the problem and your solution a little bit more and > give you feedback hopefully on monday. I'm sorry for the delay. But now I'm able to give you a detailed feedback: The general problem is, that your solution is

Re: [patch 2/3] timers: do not raise softirq unconditionally (spinlockless version)

2019-06-06 Thread Marcelo Tosatti
On Tue, Jun 04, 2019 at 02:29:31PM +0800, Peter Xu wrote: > On Mon, Apr 15, 2019 at 05:12:15PM -0300, Marcelo Tosatti wrote: > > Check base->pending_map locklessly and skip raising timer softirq > > if empty. > > > > What allows the lockless (and potentially racy against mod_timer) > > check is

Re: [patch 2/3] timers: do not raise softirq unconditionally (spinlockless version)

2019-06-04 Thread Peter Xu
On Mon, Apr 15, 2019 at 05:12:15PM -0300, Marcelo Tosatti wrote: > Check base->pending_map locklessly and skip raising timer softirq > if empty. > > What allows the lockless (and potentially racy against mod_timer) > check is that mod_timer will raise another timer softirq after > modifying

Re: [patch 2/3] timers: do not raise softirq unconditionally (spinlockless version)

2019-05-31 Thread Anna-Maria Gleixner
On Thu, 30 May 2019, Marcelo Tosatti wrote: > On Wed, May 29, 2019 at 04:53:26PM +0200, Anna-Maria Gleixner wrote: > > On Mon, 15 Apr 2019, Marcelo Tosatti wrote: > > > > > --- linux-rt-devel.orig/kernel/time/timer.c 2019-04-15 > > > 14:21:02.788704354 -0300 > > > +++

Re: [patch 2/3] timers: do not raise softirq unconditionally (spinlockless version)

2019-05-30 Thread Marcelo Tosatti
On Wed, May 29, 2019 at 04:53:26PM +0200, Anna-Maria Gleixner wrote: > On Mon, 15 Apr 2019, Marcelo Tosatti wrote: > > > Check base->pending_map locklessly and skip raising timer softirq > > if empty. > > > > What allows the lockless (and potentially racy against mod_timer) > > check is that

Re: [patch 2/3] timers: do not raise softirq unconditionally (spinlockless version)

2019-05-29 Thread Anna-Maria Gleixner
On Mon, 15 Apr 2019, Marcelo Tosatti wrote: > Check base->pending_map locklessly and skip raising timer softirq > if empty. > > What allows the lockless (and potentially racy against mod_timer) > check is that mod_timer will raise another timer softirq after > modifying base->pending_map. The

[patch 2/3] timers: do not raise softirq unconditionally (spinlockless version)

2019-04-15 Thread Marcelo Tosatti
Check base->pending_map locklessly and skip raising timer softirq if empty. What allows the lockless (and potentially racy against mod_timer) check is that mod_timer will raise another timer softirq after modifying base->pending_map. Signed-off-by: Marcelo Tosatti --- kernel/time/timer.c |