From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: hch@infradead.org, mhocko@kernel.org, minchan@kernel.org,
ying.huang@intel.com, mgorman@techsingularity.net,
vdavydov.dev@gmail.com, hannes@cmpxchg.org,
akpm@linux-foundation.org, shakeelb@google.com,
gthelen@google.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] mm,vmscan: Kill global shrinker lock.
Date: Mon, 20 Nov 2017 10:28:38 -0800 [thread overview]
Message-ID: <20171120182838.GU3624@linux.vnet.ibm.com> (raw)
In-Reply-To: <201711201956.IIB86978.OFMVFFOJLtOSHQ@I-love.SAKURA.ne.jp>
On Mon, Nov 20, 2017 at 07:56:28PM +0900, Tetsuo Handa wrote:
> Christoph Hellwig wrote:
> > On Mon, Nov 20, 2017 at 10:42:37AM +0100, Michal Hocko wrote:
> > > The patch has been dropped because allnoconfig failed to compile back
> > > then http://lkml.kernel.org/r/CAP=VYLr0rPWi1aeuk4w1On9CYRNmnEWwJgGtaX=wEvGaBURtrg@mail.gmail.com
> > > I have problem to find the follow up discussion though. The main
> > > argument was that SRC is not generally available and so the core
> > > kernel should rely on it.
> >
> > Paul,
> >
> > isthere any good reason to not use SRCU in the core kernel and
> > instead try to reimplement it using atomic counters?
>
> CONFIG_SRCU was added in order to save system size. There are users who run Linux on very
> small systems ( https://www.elinux.org/images/5/52/Status-of-embedded-Linux-2017-09-JJ62.pdf ).
>
> Also, atomic counters are not mandatory for shrinker case; e.g.
> http://lkml.kernel.org/r/201711161956.EBF57883.QFFMOLOVSOHJFt@I-love.SAKURA.ne.jp .
CONFIG_SRCU was indeed added in order to shrink single-CPU systems.
But many architectures are now requiring SRCU for one reason or another,
in more and more situations.
So I recently implemented a UP-only Tiny SRCU, which is quite a bit
smaller than its scalable counterpart, Tree SRCU:
text data bss dec hex filename
983 64 0 1047 417 /tmp/c/kernel/rcu/srcutiny.o
text data bss dec hex filename
6844 193 0 7037 1b7d /tmp/b/kernel/rcu/srcutree.o
So perhaps it is time to unconditionally enable SRCU?
Thanx, Paul
WARNING: multiple messages have this Message-ID (diff)
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: hch@infradead.org, mhocko@kernel.org, minchan@kernel.org,
ying.huang@intel.com, mgorman@techsingularity.net,
vdavydov.dev@gmail.com, hannes@cmpxchg.org,
akpm@linux-foundation.org, shakeelb@google.com,
gthelen@google.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] mm,vmscan: Kill global shrinker lock.
Date: Mon, 20 Nov 2017 10:28:38 -0800 [thread overview]
Message-ID: <20171120182838.GU3624@linux.vnet.ibm.com> (raw)
In-Reply-To: <201711201956.IIB86978.OFMVFFOJLtOSHQ@I-love.SAKURA.ne.jp>
On Mon, Nov 20, 2017 at 07:56:28PM +0900, Tetsuo Handa wrote:
> Christoph Hellwig wrote:
> > On Mon, Nov 20, 2017 at 10:42:37AM +0100, Michal Hocko wrote:
> > > The patch has been dropped because allnoconfig failed to compile back
> > > then http://lkml.kernel.org/r/CAP=VYLr0rPWi1aeuk4w1On9CYRNmnEWwJgGtaX=wEvGaBURtrg@mail.gmail.com
> > > I have problem to find the follow up discussion though. The main
> > > argument was that SRC is not generally available and so the core
> > > kernel should rely on it.
> >
> > Paul,
> >
> > isthere any good reason to not use SRCU in the core kernel and
> > instead try to reimplement it using atomic counters?
>
> CONFIG_SRCU was added in order to save system size. There are users who run Linux on very
> small systems ( https://www.elinux.org/images/5/52/Status-of-embedded-Linux-2017-09-JJ62.pdf ).
>
> Also, atomic counters are not mandatory for shrinker case; e.g.
> http://lkml.kernel.org/r/201711161956.EBF57883.QFFMOLOVSOHJFt@I-love.SAKURA.ne.jp .
CONFIG_SRCU was indeed added in order to shrink single-CPU systems.
But many architectures are now requiring SRCU for one reason or another,
in more and more situations.
So I recently implemented a UP-only Tiny SRCU, which is quite a bit
smaller than its scalable counterpart, Tree SRCU:
text data bss dec hex filename
983 64 0 1047 417 /tmp/c/kernel/rcu/srcutiny.o
text data bss dec hex filename
6844 193 0 7037 1b7d /tmp/b/kernel/rcu/srcutree.o
So perhaps it is time to unconditionally enable SRCU?
Thanx, Paul
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2017-11-20 18:28 UTC|newest]
Thread overview: 74+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-13 21:37 [PATCH 1/2] mm,vmscan: Kill global shrinker lock Tetsuo Handa
2017-11-13 21:37 ` Tetsuo Handa
2017-11-13 21:37 ` [PATCH 2/2] mm,vmscan: Allow parallel registration/unregistration of shrinkers Tetsuo Handa
2017-11-13 21:37 ` Tetsuo Handa
2017-11-13 22:05 ` [PATCH 1/2] mm,vmscan: Kill global shrinker lock Shakeel Butt
2017-11-13 22:05 ` Shakeel Butt
2017-11-15 0:56 ` Minchan Kim
2017-11-15 0:56 ` Minchan Kim
2017-11-15 6:28 ` Shakeel Butt
2017-11-15 6:28 ` Shakeel Butt
2017-11-16 0:46 ` Minchan Kim
2017-11-16 0:46 ` Minchan Kim
2017-11-16 1:41 ` Shakeel Butt
2017-11-16 1:41 ` Shakeel Butt
2017-11-16 4:50 ` Minchan Kim
2017-11-16 4:50 ` Minchan Kim
2017-11-15 8:56 ` Michal Hocko
2017-11-15 8:56 ` Michal Hocko
2017-11-15 9:18 ` Michal Hocko
2017-11-15 9:18 ` Michal Hocko
2017-11-16 17:44 ` Johannes Weiner
2017-11-16 17:44 ` Johannes Weiner
2017-11-23 23:46 ` Minchan Kim
2017-11-23 23:46 ` Minchan Kim
2017-11-15 9:02 ` Michal Hocko
2017-11-15 9:02 ` Michal Hocko
2017-11-15 10:58 ` Tetsuo Handa
2017-11-15 10:58 ` Tetsuo Handa
2017-11-15 11:51 ` Michal Hocko
2017-11-15 11:51 ` Michal Hocko
2017-11-16 0:56 ` Minchan Kim
2017-11-16 0:56 ` Minchan Kim
2017-11-15 13:28 ` Johannes Weiner
2017-11-15 13:28 ` Johannes Weiner
2017-11-16 10:56 ` Tetsuo Handa
2017-11-16 10:56 ` Tetsuo Handa
2017-11-15 14:00 ` Johannes Weiner
2017-11-15 14:00 ` Johannes Weiner
2017-11-15 14:11 ` Michal Hocko
2017-11-15 14:11 ` Michal Hocko
2018-01-25 2:04 ` Tetsuo Handa
2018-01-25 2:04 ` Tetsuo Handa
2018-01-25 8:36 ` Michal Hocko
2018-01-25 8:36 ` Michal Hocko
2018-01-25 10:56 ` Tetsuo Handa
2018-01-25 10:56 ` Tetsuo Handa
2018-01-25 11:41 ` Michal Hocko
2018-01-25 11:41 ` Michal Hocko
2018-01-25 22:19 ` Eric Wheeler
2018-01-25 22:19 ` Eric Wheeler
2018-01-26 3:12 ` Tetsuo Handa
2018-01-26 3:12 ` Tetsuo Handa
2018-01-26 10:08 ` Michal Hocko
2018-01-26 10:08 ` Michal Hocko
2017-11-17 17:35 ` Christoph Hellwig
2017-11-17 17:35 ` Christoph Hellwig
2017-11-17 17:41 ` Shakeel Butt
2017-11-17 17:41 ` Shakeel Butt
2017-11-17 17:53 ` Shakeel Butt
2017-11-17 17:53 ` Shakeel Butt
2017-11-17 18:36 ` Christoph Hellwig
2017-11-17 18:36 ` Christoph Hellwig
2017-11-20 9:25 ` Michal Hocko
2017-11-20 9:25 ` Michal Hocko
2017-11-20 9:33 ` Christoph Hellwig
2017-11-20 9:33 ` Christoph Hellwig
2017-11-20 9:42 ` Michal Hocko
2017-11-20 9:42 ` Michal Hocko
2017-11-20 10:41 ` Christoph Hellwig
2017-11-20 10:41 ` Christoph Hellwig
2017-11-20 10:56 ` Tetsuo Handa
2017-11-20 10:56 ` Tetsuo Handa
2017-11-20 18:28 ` Paul E. McKenney [this message]
2017-11-20 18:28 ` Paul E. McKenney
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=20171120182838.GU3624@linux.vnet.ibm.com \
--to=paulmck@linux.vnet.ibm.com \
--cc=akpm@linux-foundation.org \
--cc=gthelen@google.com \
--cc=hannes@cmpxchg.org \
--cc=hch@infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mgorman@techsingularity.net \
--cc=mhocko@kernel.org \
--cc=minchan@kernel.org \
--cc=penguin-kernel@I-love.SAKURA.ne.jp \
--cc=shakeelb@google.com \
--cc=vdavydov.dev@gmail.com \
--cc=ying.huang@intel.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.