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From: Stephen Rothwell <sfr@canb.auug.org.au>
To: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: akpm@linux-foundation.org, gregkh@linuxfoundation.org,
	rafael@kernel.org, viro@zeniv.linux.org.uk,
	darrick.wong@oracle.com, paulmck@linux.vnet.ibm.com,
	josh@joshtriplett.org, 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,
	vdavydov.dev@gmail.com, mhocko@suse.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
Date: Wed, 8 Aug 2018 21:04:50 +1000	[thread overview]
Message-ID: <20180808210450.02108372@canb.auug.org.au> (raw)
In-Reply-To: <9ac119a7-4142-3a5a-6c4b-6f35ad026cb0@virtuozzo.com>

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Hi Kirill,

On Wed, 8 Aug 2018 12:59:40 +0300 Kirill Tkhai <ktkhai@virtuozzo.com> wrote:
>
> On 08.08.2018 04:08, Stephen Rothwell wrote:
> > 
> > So what sort of overheads (in terms of code size and performance) are
> > we adding by having SRCU enabled where it used not to be?  
> 
> SRCU is unconditionally enabled for x86, so I had to use another arch (sparc64)
> to check the size difference. The config, I used to compile, is attached, SRCU
> was enabled via:
> 
> diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
> index 2d58c26bff9a..6e9116e356d4 100644
> --- a/arch/sparc/Kconfig
> +++ b/arch/sparc/Kconfig
> @@ -15,6 +15,7 @@ config SPARC
>  	select ARCH_MIGHT_HAVE_PC_PARPORT if SPARC64 && PCI
>  	select ARCH_MIGHT_HAVE_PC_SERIO
>  	select OF
> +	select SRCU
>  	select OF_PROMTREE
>  	select HAVE_IDE
>  	select HAVE_OPROFILE
> 
> $ 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

Thanks for that.

> I have not ideas about performance overhead measurements. If you have ideas,
> where they may occur, please say. At the first sight, there should not be
> a problem, since SRCU is enabled in x86 by default.

I have no idea, just asking questions that might be relevant for
platforms where SRCU is normally disabled.

-- 
Cheers,
Stephen Rothwell

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  reply	other threads:[~2018-08-08 11:05 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-07 15:37 [PATCH RFC 00/10] Introduce lockless shrink_slab() Kirill Tkhai
2018-08-07 15:37 ` [PATCH RFC 01/10] rcu: Make CONFIG_SRCU unconditionally enabled Kirill Tkhai
2018-08-08  0:55   ` Steven Rostedt
2018-08-08  1:05   ` Stephen Rothwell
2018-08-08  9:46     ` Kirill Tkhai
2018-08-08  1:08   ` Stephen Rothwell
2018-08-08  9:59     ` Kirill Tkhai
2018-08-08 11:04       ` Stephen Rothwell [this message]
2018-08-08  7:20   ` Michal Hocko
2018-08-08 10:17     ` Kirill Tkhai
2018-08-08 10:27       ` Michal Hocko
2018-08-08 21:31         ` Dave Chinner
2018-08-09  0:07           ` Matthew Wilcox
2018-08-09  7:45             ` Greg KH
2018-08-09 10:22           ` Kirill Tkhai
2018-08-08 16:13       ` Josh Triplett
2018-08-08 16:23         ` Kirill Tkhai
2018-08-08 16:30           ` Kirill Tkhai
2018-08-08 18:01             ` Josh Triplett
2018-08-08 23:02               ` Shakeel Butt
2018-08-08 23:09                 ` Josh Triplett
2018-08-07 15:37 ` [PATCH RFC 02/10] mm: Make shrink_slab() lockless Kirill Tkhai
2018-08-08 11:51   ` Kirill Tkhai
2018-08-08 12:36     ` Tetsuo Handa
2018-08-08 12:51       ` Kirill Tkhai
2018-08-08 13:20     ` [PATCH RFC v2 " Kirill Tkhai
2018-08-09  7:14       ` Michal Hocko
2018-08-09  9:21         ` Kirill Tkhai
2018-08-09 10:37           ` Tetsuo Handa
2018-08-09 10:58             ` Kirill Tkhai
2018-08-09 11:23         ` Kirill Tkhai
2018-08-07 15:38 ` [PATCH RFC 03/10] mm: Convert shrinker_rwsem to mutex Kirill Tkhai
2018-08-07 15:38 ` [PATCH RFC 04/10] mm: Split unregister_shrinker() Kirill Tkhai
2018-08-07 15:38 ` [PATCH RFC 05/10] fs: Move list_lru_destroy() to destroy_super_work() Kirill Tkhai
2018-08-07 15:38 ` [PATCH RFC 06/10] fs: Shrink only (SB_ACTIVE|SB_BORN) superblocks in super_cache_scan() Kirill Tkhai
2018-08-07 15:38 ` [PATCH RFC 07/10] fs: Introduce struct super_operations::destroy_super() callback Kirill Tkhai
2018-08-07 15:39 ` [PATCH RFC 08/10] xfs: Introduce xfs_fs_destroy_super() Kirill Tkhai
2018-08-07 15:39 ` [PATCH RFC 09/10] shmem: Implement shmem_destroy_super() Kirill Tkhai
2018-08-07 15:39 ` [PATCH RFC 10/10] fs: Use unregister_shrinker_delayed_{initiate, finalize} for super_block shrinker Kirill Tkhai
2018-08-08  1:12 ` [PATCH RFC 00/10] Introduce lockless shrink_slab() Stephen Rothwell
2018-08-08  5:39   ` Shakeel Butt
2018-08-08 10:18     ` Kirill Tkhai

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