From: Thomas Gleixner <tglx@linutronix.de>
To: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
linux-arch@vger.kernel.org, Peter Zijlstra <peterz@infradead.org>,
Rusty Russell <rusty@rustcorp.com.au>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Ingo Molnar <mingo@kernel.org>,
Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>,
Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [patch 00/18] SMP: Boot and CPU hotplug refactoring - Part 1
Date: Fri, 20 Apr 2012 16:18:04 +0200 (CEST) [thread overview]
Message-ID: <alpine.LFD.2.02.1204201602330.2542@ionos> (raw)
In-Reply-To: <4F916AF3.7020301@linux.vnet.ibm.com>
On Fri, 20 Apr 2012, Srivatsa S. Bhat wrote:
> > This first part moves the idle thread management for non-boot cpus
> > into the core. fork_idle() is called in a workqueue as it is
> > implemented in a few architectures already. This is necessary when not
> > all cpus are brought up by the early boot code as otherwise we would
> > take a ref on the user task VM of the thread which brings the cpu up
> > via the sysfs interface.
> >
>
>
> Do you have a git tree where you have made these patches available?
> That would be pretty useful, so that we can build on whatever you have
Not yet, but I'll stick that into a tip/ branch.
> already done.. Myself and Nikunj had some initial design/ideas on reducing
> the duplication in architecture code, related to managing the setting
> of the cpu in the online mask, sending out CPU_STARTING notifiers etc
> from generic code..
The whole notifier business needs a redesign as well, because we don't
have a way to express proper dependencies, we add random notifier
points and the teardown path is ass backwards. The whole thing wants
to be a tree which can be walked in either direction and from any
point. Right now we cut the trunk first and keep the single limb up
with a helicopter and start dismantling it.
Flat notifiers are not working for this as they do not allow a tree
structure and prevent us to do things in parallel.
That really needs to be completely reworked. There is also a lot of
stuff which wants to be moved into the starting/dying CPU
context. Right now we kinda do that by trampling on the CPU with a
high prio stomper thread, but that's really just a bandaid and steady
cause of trouble.
If you look at facilities which use kthreads, then there is lots other
setup which does not need a notifier at all, as it can be done in the
context of the thread when we have a way to start/park those threads
at the right time in the up/down process.
I've already done a prototype for kthread park/unpark and converted
softirq over to use it. That makes the complete softirq notifier go
away and let the core code handle the thread creation / start / park /
unpark. It's pretty hacky right now, but I'm going to push on this
next, once I have a better idea how to express the dependency tree.
Thanks,
tglx
next prev parent reply other threads:[~2012-04-20 14:18 UTC|newest]
Thread overview: 82+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-20 13:05 [patch 00/18] SMP: Boot and CPU hotplug refactoring - Part 1 Thomas Gleixner
2012-04-20 13:05 ` [patch 01/18] m32r: Remove pointless function prototypes Thomas Gleixner
2012-04-20 13:05 ` [patch 02/18] smp: Add task_struct argument to __cpu_up() Thomas Gleixner
2012-04-20 13:05 ` Thomas Gleixner
2012-04-23 7:58 ` Jesper Nilsson
2012-04-23 7:58 ` Jesper Nilsson
2012-04-20 13:05 ` [patch 03/18] smp: Add generic smpboot facility Thomas Gleixner
2012-04-20 13:05 ` Thomas Gleixner
2012-04-20 20:07 ` Yinghai Lu
2012-04-20 20:07 ` Yinghai Lu
2012-04-21 2:07 ` Stephen Rothwell
2012-04-21 2:07 ` Stephen Rothwell
2012-04-20 13:05 ` [patch 04/18] smp: Provide generic idle thread allocation Thomas Gleixner
2012-04-20 13:05 ` Thomas Gleixner
2012-04-20 16:21 ` Sam Ravnborg
2012-04-20 16:21 ` Sam Ravnborg
2012-04-20 18:55 ` Thomas Gleixner
2012-04-20 18:55 ` Thomas Gleixner
2012-04-21 2:20 ` Stephen Rothwell
2012-04-21 2:20 ` Stephen Rothwell
2012-04-21 2:25 ` Frank Rowand
2012-04-21 2:25 ` Frank Rowand
2012-04-20 13:05 ` [patch 05/18] x86: Add task_struct argument to smp_ops.cpu_up Thomas Gleixner
2012-04-20 13:05 ` [patch 06/18] x86: Use generic idle thread allocation Thomas Gleixner
2012-04-20 13:05 ` [patch 07/18] powerpc: " Thomas Gleixner
2012-04-20 13:05 ` Thomas Gleixner
2012-04-20 13:05 ` [patch 08/18] ia64: " Thomas Gleixner
2012-04-20 13:05 ` [patch 09/18] arm: " Thomas Gleixner
2012-04-20 13:05 ` Thomas Gleixner
2012-04-20 13:05 ` [patch 11/18] hexagon: " Thomas Gleixner
2012-04-20 13:05 ` Thomas Gleixner
2012-04-24 16:47 ` Richard Kuo
2012-04-24 16:47 ` Richard Kuo
2012-04-20 13:05 ` [patch 10/18] mips: " Thomas Gleixner
2012-04-20 13:05 ` Thomas Gleixner
2012-04-20 13:05 ` [patch 12/18] s390: " Thomas Gleixner
2012-04-20 13:05 ` Thomas Gleixner
2012-04-23 7:09 ` Martin Schwidefsky
2012-04-23 7:09 ` Martin Schwidefsky
2012-04-20 13:05 ` [patch 13/18] blackfin: " Thomas Gleixner
2012-04-20 13:05 ` [patch 14/18] cris: " Thomas Gleixner
2012-04-23 7:57 ` Jesper Nilsson
2012-04-23 7:57 ` Jesper Nilsson
2012-04-20 13:05 ` [patch 15/18] sh: " Thomas Gleixner
2012-04-20 13:05 ` Thomas Gleixner
2012-04-21 3:18 ` Paul Mundt
2012-04-20 13:05 ` [patch 16/18] alpha: " Thomas Gleixner
2012-04-20 13:05 ` Thomas Gleixner
2012-04-20 13:05 ` [patch 17/18] parisc: " Thomas Gleixner
2012-04-20 13:05 ` Thomas Gleixner
2012-04-20 13:05 ` [patch 18/18] sparc: " Thomas Gleixner
2012-04-20 13:05 ` Thomas Gleixner
2012-04-22 19:52 ` David Miller
2012-04-20 13:16 ` [patch 00/18] SMP: Boot and CPU hotplug refactoring - Part 1 Thomas Gleixner
2012-04-20 13:21 ` Peter Zijlstra
2012-04-20 13:47 ` Thomas Gleixner
2012-04-21 0:08 ` Suresh Siddha
2012-05-03 9:41 ` Thomas Gleixner
2012-05-03 9:41 ` Thomas Gleixner
2012-05-03 23:42 ` Suresh Siddha
2012-04-20 15:42 ` Tejun Heo
2012-04-20 15:49 ` Peter Zijlstra
2012-04-20 15:56 ` Thomas Gleixner
2012-04-20 13:56 ` Srivatsa S. Bhat
2012-04-20 14:18 ` Thomas Gleixner [this message]
2012-04-24 18:44 ` Konrad Rzeszutek Wilk
2012-05-21 1:42 ` Rusty Russell
2012-05-21 8:25 ` Thomas Gleixner
2012-05-21 8:25 ` Thomas Gleixner
2012-05-22 0:53 ` Rusty Russell
2012-04-20 14:06 ` richard -rw- weinberger
2012-04-20 14:06 ` richard -rw- weinberger
2012-04-20 14:19 ` Thomas Gleixner
2012-04-20 14:27 ` James Bottomley
2012-04-20 17:55 ` Paul E. McKenney
2012-04-20 23:11 ` Venki Pallipadi
2012-04-21 1:04 ` Frank Rowand
2012-04-21 1:55 ` Frank Rowand
2012-04-22 21:01 ` Chris Metcalf
2012-04-22 21:01 ` Chris Metcalf
2012-04-30 8:05 ` Santosh Shilimkar
2012-04-30 8:05 ` Santosh Shilimkar
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=alpine.LFD.2.02.1204201602330.2542@ionos \
--to=tglx@linutronix.de \
--cc=linux-arch@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=nikunj@linux.vnet.ibm.com \
--cc=paulmck@linux.vnet.ibm.com \
--cc=peterz@infradead.org \
--cc=rostedt@goodmis.org \
--cc=rusty@rustcorp.com.au \
--cc=srivatsa.bhat@linux.vnet.ibm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).