Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Wed, 8 Aug 2018 09:13:30 -0700
From:   Josh Triplett <josh@joshtriplett.org>
To:     Kirill Tkhai <ktkhai@virtuozzo.com>
Cc:     Michal Hocko <mhocko@kernel.org>, akpm@linux-foundation.org,
        gregkh@linuxfoundation.org, rafael@kernel.org,
        viro@zeniv.linux.org.uk, darrick.wong@oracle.com,
        paulmck@linux.vnet.ibm.com, rostedt@goodmis.org,
        mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com,
        hughd@google.com, shuah@kernel.org, robh@kernel.org,
        ulf.hansson@linaro.org, aspriel@gmail.com,
        vivek.gautam@codeaurora.org, robin.murphy@arm.com, joe@perches.com,
        heikki.krogerus@linux.intel.com, sfr@canb.auug.org.au,
        vdavydov.dev@gmail.com, chris@chris-wilson.co.uk,
        penguin-kernel@I-love.SAKURA.ne.jp, aryabinin@virtuozzo.com,
        willy@infradead.org, ying.huang@intel.com, shakeelb@google.com,
        jbacik@fb.com, mingo@kernel.org, mhiramat@kernel.org,
        linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        linux-mm@kvack.org
Subject: Re: [PATCH RFC 01/10] rcu: Make CONFIG_SRCU unconditionally enabled
Message-ID: <20180808161330.GA22863@localhost>
References: <153365347929.19074.12509495712735843805.stgit@localhost.localdomain>
 <153365625652.19074.8434946780002619802.stgit@localhost.localdomain>
 <20180808072040.GC27972@dhcp22.suse.cz>
 <d17e65bb-c114-55de-fb4e-e2f538779b92@virtuozzo.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <d17e65bb-c114-55de-fb4e-e2f538779b92@virtuozzo.com>
User-Agent: Mutt/1.10.1 (2018-07-13)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Wed, Aug 08, 2018 at 01:17:44PM +0300, Kirill Tkhai wrote:
> On 08.08.2018 10:20, Michal Hocko wrote:
> > On Tue 07-08-18 18:37:36, Kirill Tkhai wrote:
> >> This patch kills all CONFIG_SRCU defines and
> >> the code under !CONFIG_SRCU.
> > 
> > The last time somebody tried to do this there was a pushback due to
> > kernel tinyfication. So this should really give some numbers about the
> > code size increase. Also why can't we make this depend on MMU. Is
> > anybody else than the reclaim asking for unconditional SRCU usage?
> 
> I don't know one. The size numbers (sparc64) are:
> 
> $ size image.srcu.disabled 
>    text	   data	    bss	    dec	    hex	filename
> 5117546	8030506	1968104	15116156	 e6a77c	image.srcu.disabled
> $ size image.srcu.enabled
>    text	   data	    bss	    dec	    hex	filename
> 5126175	8064346	1968104	15158625	 e74d61	image.srcu.enabled
> The difference is: 15158625-15116156 = 42469 ~41Kb

41k is a *substantial* size increase. However, can you compare
tinyconfig with and without this patch? That may have a smaller change.