Linux-rt-users archive on lore.kernel.org
 help / color / Atom feed
* remove of ktimersoftd in linux-rt-devel 5.0
@ 2020-05-15 23:46 Alison Chaiken
  2020-05-26 14:24 ` Sebastian Andrzej Siewior
  0 siblings, 1 reply; 2+ messages in thread
From: Alison Chaiken @ 2020-05-15 23:46 UTC (permalink / raw)
  To: linux-rt-users

About a year ago the following commit greatly simplified softirqs:

commit 6f6ba7715a91877cf5fd2b357db3799baa331d9b
Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date:   Wed May 29 18:47:32 2019 +0200
    softirq: rework

It also removed ktimersoftd, without comment as far as I can see.  Is
it obvious that performance improvements due to lockless
synchronization render useless the earlier split of ktimersoftd from
ksoftirqd?   Is it now less likely that a large number of other
softirqs that are run immediately when hard IRQs terminate will use up
ksoftirqd's time slice and prevent the timer softirqs from getting a
chance to run?

Thanks,
Alison Chaiken
achaiken@aurora.tech
Aurora Innovation

^ permalink raw reply	[flat|nested] 2+ messages in thread

* Re: remove of ktimersoftd in linux-rt-devel 5.0
  2020-05-15 23:46 remove of ktimersoftd in linux-rt-devel 5.0 Alison Chaiken
@ 2020-05-26 14:24 ` Sebastian Andrzej Siewior
  0 siblings, 0 replies; 2+ messages in thread
From: Sebastian Andrzej Siewior @ 2020-05-26 14:24 UTC (permalink / raw)
  To: Alison Chaiken; +Cc: linux-rt-users

On 2020-05-15 16:46:48 [-0700], Alison Chaiken wrote:
> About a year ago the following commit greatly simplified softirqs:
> 
> commit 6f6ba7715a91877cf5fd2b357db3799baa331d9b
> Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> Date:   Wed May 29 18:47:32 2019 +0200
>     softirq: rework
> 
> It also removed ktimersoftd, without comment as far as I can see.  Is
> it obvious that performance improvements due to lockless
> synchronization render useless the earlier split of ktimersoftd from
> ksoftirqd?   Is it now less likely that a large number of other
> softirqs that are run immediately when hard IRQs terminate will use up
> ksoftirqd's time slice and prevent the timer softirqs from getting a
> chance to run?

When hard IRQs terminate and raise the softirq then the ksoftirqd is
woken up. The softirq may be processed by the thread _or_ by anything
else that is running happens to process softirqs. That can be any
force-threaded interrupt handler.
In general nothing raises softirqs from hardirq context. One exception
here are POSIX timer. The plan was to rework POSIX-timer code.

Sebastian

^ permalink raw reply	[flat|nested] 2+ messages in thread

end of thread, back to index

Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-05-15 23:46 remove of ktimersoftd in linux-rt-devel 5.0 Alison Chaiken
2020-05-26 14:24 ` Sebastian Andrzej Siewior

Linux-rt-users archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-rt-users/0 linux-rt-users/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-rt-users linux-rt-users/ https://lore.kernel.org/linux-rt-users \
		linux-rt-users@vger.kernel.org
	public-inbox-index linux-rt-users

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-rt-users


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git