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From: Nitin Gupta <ngupta@vflare.org>
To: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/2] [mmotm] Add notifiers for various swap events
Date: Mon, 28 Dec 2009 15:51:31 +0530	[thread overview]
Message-ID: <d760cf2d0912280221s7d24fac6u571243fdd2c71862@mail.gmail.com> (raw)
In-Reply-To: <84144f020912272213u38389b79i25a0f50855d55673@mail.gmail.com>

On Mon, Dec 28, 2009 at 11:43 AM, Pekka Enberg <penberg@cs.helsinki.fi> wrote:
> On Mon, Dec 28, 2009 at 3:19 AM, Nitin Gupta <ngupta@vflare.org> wrote:
>> Events:
>>  - Swapon
>>  - Swapoff
>>  - When a swap slot is freed

<snip>

> This looks good to me. Hugh? Nitin, does this patch cause any
> performance hit for the !CONFIG_RAMZSWAP case?
>

I have not yet collected any data to check overhead in !RAMZSWAP
case but an empty notifier chain is essentially equivalent to:

rcu_read_lock()
        nb = rcu_dereference(*nl);
rcu_read_unlock()

This should not cause any performance problem. Anyway, I will
try to come up with some numbers to confirm this.

Thanks for looking into this.
Nitin

  reply	other threads:[~2009-12-28 10:21 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-12-28  1:19 Nitin Gupta
2009-12-28  1:20 ` [PATCH 2/2] [mmotm] ramzswap: add handlers " Nitin Gupta
2009-12-28 16:26   ` Yin Kangkai
2009-12-29  2:42     ` Nitin Gupta
2009-12-28  6:13 ` [PATCH 1/2] [mmotm] Add notifiers " Pekka Enberg
2009-12-28 10:21   ` Nitin Gupta [this message]
2009-12-28 15:02 ` Andi Kleen
2009-12-28 15:37   ` Nitin Gupta
2009-12-28 17:29     ` Andi Kleen
2009-12-28 18:43       ` Pekka Enberg
2009-12-28 19:23         ` Andi Kleen
2009-12-29  2:41           ` Nitin Gupta

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