From: Byungchul Park <byungchul.park@lge.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Byungchul Park <max.byungchul.park@gmail.com>,
Ingo Molnar <mingo@kernel.org>, Tejun Heo <tj@kernel.org>,
Boqun Feng <boqun.feng@gmail.com>,
david@fromorbit.com, Johannes Berg <johannes@sipsolutions.net>,
oleg@redhat.com,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
kernel-team@lge.com
Subject: Re: [PATCH 4/4] lockdep: Fix workqueue crossrelease annotation
Date: Tue, 5 Sep 2017 09:38:45 +0900 [thread overview]
Message-ID: <20170905003844.GO3240@X58A-UD3R> (raw)
In-Reply-To: <20170904114248.kls4jv2ggsv46mli@hirez.programming.kicks-ass.net>
On Mon, Sep 04, 2017 at 01:42:48PM +0200, Peter Zijlstra wrote:
> On Mon, Sep 04, 2017 at 10:30:32AM +0900, Byungchul Park wrote:
> > On Fri, Sep 01, 2017 at 06:38:52PM +0200, Peter Zijlstra wrote:
> > > And get tangled up with the workqueue annotation again, no thanks.
> > > Having the first few works see the thread setup isn't worth it.
> > >
> > > And your work_id annotation had the same problem.
> >
> > I keep asking you for an example because I really understand you.
> >
> > Fix my problematic example with your patches,
> >
> > or,
> >
> > Show me a problematic scenario with my original code, you expect.
> >
> > Whatever, it would be helpful to understand you.
>
> I _really_ don't understand what you're worried about. Is it the kthread
> create and workqueue init or the pool->lock that is released/acquired in
> process_one_work()?
s/in process_one_work()/in all worker code including setup code/
Original code was already designed to handle real dependencies well. But
you invalidated it _w/o_ any reason, that's why I don't agree with your
patches. Your patches only do avoiding the wq issue now we focus on.
Look at:
worker thread another context
------------- ---------------
wait_for_completion()
|
| (1)
v
+---------+
| Work A | (2)
+---------+
|
| (3)
v
+---------+
| Work B | (4)
+---------+
|
| (5)
v
+---------+
| Work C | (6)
+---------+
|
v
We have to consider whole context of the worker to build dependencies
with a crosslock e.g. wait_for_commplete().
Only thing we have to care here is to make all works e.g. (2), (4) and
(6) independent, because workqueue does _concurrency control_. As I said
last year at the very beginning, for works not applied the control e.g.
max_active == 1, we don't need that isolation. I said, it's a future work.
It would have been much easier to communicate with each other if you
*tried* to understand my examples like now or you *tried* to give me one
example at least. You didn't even *try*. Only thing I want to ask you
for is to *try* to understand my opinions on conflicts.
Now, understand what I intended? Still unsufficient?
next prev parent reply other threads:[~2017-09-05 0:38 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-23 11:58 [PATCH 0/4] workqueue and lockdep stuffs Peter Zijlstra
2017-08-23 11:58 ` [PATCH 1/4] workqueue: Use TASK_IDLE Peter Zijlstra
2017-08-23 13:31 ` Tejun Heo
2017-08-23 11:58 ` [PATCH 2/4] lockdep/selftests: Add mixed read-write ABBA tests Peter Zijlstra
2017-08-23 11:58 ` [PATCH 3/4] workqueue/lockdep: Fix flush_work() annotation Peter Zijlstra
2017-08-23 11:58 ` [PATCH 4/4] lockdep: Fix workqueue crossrelease annotation Peter Zijlstra
2017-08-24 2:18 ` Byungchul Park
2017-08-24 14:02 ` Peter Zijlstra
2017-08-25 1:11 ` Byungchul Park
2017-08-29 8:59 ` Peter Zijlstra
2017-08-29 14:23 ` [tip:locking/core] locking/lockdep: Untangle xhlock history save/restore from task independence tip-bot for Peter Zijlstra
2017-08-29 16:02 ` [PATCH 4/4] lockdep: Fix workqueue crossrelease annotation Byungchul Park
2017-08-29 18:47 ` Peter Zijlstra
2017-08-30 2:09 ` Byungchul Park
2017-08-30 7:41 ` Byungchul Park
2017-08-30 8:53 ` Peter Zijlstra
2017-08-30 9:01 ` Byungchul Park
2017-08-30 9:12 ` Peter Zijlstra
2017-08-30 9:14 ` Peter Zijlstra
2017-08-30 9:35 ` Byungchul Park
2017-08-30 9:24 ` Byungchul Park
2017-08-30 11:25 ` Byungchul Park
2017-08-30 12:49 ` Byungchul Park
2017-08-31 7:26 ` Byungchul Park
2017-08-31 8:04 ` Peter Zijlstra
2017-08-31 8:15 ` Byungchul Park
2017-08-31 8:34 ` Peter Zijlstra
2017-09-01 2:05 ` Byungchul Park
2017-09-01 9:47 ` Peter Zijlstra
2017-09-01 10:16 ` Byungchul Park
2017-09-01 12:09 ` 박병철/선임연구원/SW Platform(연)AOT팀(byungchul.park@lge.com)
2017-09-01 12:38 ` Peter Zijlstra
2017-09-01 13:51 ` Byungchul Park
2017-09-01 16:38 ` Peter Zijlstra
2017-09-04 1:30 ` Byungchul Park
2017-09-04 2:08 ` Byungchul Park
2017-09-04 11:42 ` Peter Zijlstra
2017-09-05 0:38 ` Byungchul Park [this message]
2017-09-05 7:08 ` Peter Zijlstra
2017-09-05 7:19 ` Peter Zijlstra
2017-09-05 8:57 ` Byungchul Park
2017-09-05 9:36 ` Peter Zijlstra
2017-09-05 10:31 ` Byungchul Park
2017-09-05 10:52 ` Peter Zijlstra
2017-09-05 11:24 ` Byungchul Park
2017-09-05 10:58 ` Byungchul Park
2017-09-05 13:46 ` Peter Zijlstra
2017-09-05 23:52 ` Byungchul Park
2017-09-06 0:42 ` Boqun Feng
2017-09-06 1:32 ` Byungchul Park
2017-09-06 23:59 ` Byungchul Park
2017-09-07 0:11 ` Byungchul Park
2017-09-06 0:48 ` Byungchul Park
2017-09-05 8:30 ` Byungchul Park
2017-08-31 8:07 ` Peter Zijlstra
2017-08-25 4:39 ` Byungchul Park
2017-08-29 6:46 ` Byungchul Park
2017-08-29 9:01 ` Peter Zijlstra
2017-08-29 16:12 ` Byungchul Park
2017-08-23 13:32 ` [PATCH 0/4] workqueue and lockdep stuffs Tejun Heo
2017-08-23 13:45 ` Peter Zijlstra
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=20170905003844.GO3240@X58A-UD3R \
--to=byungchul.park@lge.com \
--cc=boqun.feng@gmail.com \
--cc=david@fromorbit.com \
--cc=johannes@sipsolutions.net \
--cc=kernel-team@lge.com \
--cc=linux-kernel@vger.kernel.org \
--cc=max.byungchul.park@gmail.com \
--cc=mingo@kernel.org \
--cc=oleg@redhat.com \
--cc=peterz@infradead.org \
--cc=tj@kernel.org \
/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).