From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Ingo Molnar <mingo@kernel.org>
Cc: linux-kernel@vger.kernel.org
Subject: Re: FYI, tiny-kernel fix for rcu_segcblist separate .c file
Date: Sat, 6 May 2017 09:51:47 -0700 [thread overview]
Message-ID: <20170506165147.GR3956@linux.vnet.ibm.com> (raw)
In-Reply-To: <20170506071551.owtodttlhwvjrtzp@gmail.com>
On Sat, May 06, 2017 at 09:15:51AM +0200, Ingo Molnar wrote:
>
> * Paul E. McKenney <paulmck@linux.vnet.ibm.com> wrote:
>
> > Hello, Ingo,
> >
> > Just in case you get complaints about kernel size...
> >
> > In response to Linus's feedback, I did commit 98059b98619d ("rcu:
> > Separately compile large rcu_segcblist functions"), which of course
> > has the side-effect of bloating Tiny SRCU, which 0day Test Robot
> > complains about.
> >
> > So I have queued commit 7bf7fa5acc92 ("srcu: Apply trivial callback
> > lists to shrink Tiny SRCU"), which makes up for the bloating and then some.
> >
> > I don't believe that this debloating is at all urgent because people
> > building kernels for small-memory devices have to do a lot of other
> > tweaking, so that applying this additional commit as a patch should
> > not be too much incremental pain.
> >
> > So again, if you get complaints about 98059b98619d bloating tiny
> > kernel builds, 7bf7fa5acc92 is the fix.
>
> Ok!
>
> I do agree that it's not urgent: single CPU systems are rapidly becoming the
> exception for new hardware designed, even for embedded systems. At this point
> I think the educational value of TinyRCU is its main quality.
To your point, Tiny SRCU certainly is now quite self-contained and easy to
understand. It is arguably even simpler than Tiny RCU because there are
explicit wakeups -- no indirect reasoning about context switches required.
Some people tell me that IoT-style microcontrollers for small devices
require things like Tiny {S,}RCU, with one prominent recent example being
Nicolas Pitre with his Tiny TTY layer. On the other hand, perhaps your
argument about educational value applies to the TTY layer as well as
to RCU. Maybe even more so -- it is quite possible that there are more
people who understand RCU than understand the TTY layer. ;-)
Thanx, Paul
prev parent reply other threads:[~2017-05-06 16:52 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-05 16:13 FYI, tiny-kernel fix for rcu_segcblist separate .c file Paul E. McKenney
2017-05-06 7:15 ` Ingo Molnar
2017-05-06 16:51 ` Paul E. McKenney [this message]
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=20170506165147.GR3956@linux.vnet.ibm.com \
--to=paulmck@linux.vnet.ibm.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@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).