linux-kernel - [PATCH] memcg remvoe redundant message at swapon

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Date:	Thu, 19 Mar 2009 09:44:33 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	Hugh Dickins <hugh@...itas.com>
Cc:	nishimura@....nes.nec.co.jp,
	Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
	balbir@...ux.vnet.ibm.com, lizf@...fujitsu.com,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: [PATCH] memcg remvoe redundant message at swapon

This is based on this thread http://marc.info/?l=linux-mm&m=123724233418715&w=2
against the mmotm.
=
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>

It's pointed out that swap_cgroup's message at swapon() is nonsense.
Because
  * It can be calculated very easily if all necessary information is
    written in Kconfig.
  * It's not necessary to annoying people at every swapon().

In other view, now, memory usage per swp_entry is reduced to 2bytes
from 8bytes(64bit) and I think it's reasonably small.

Reported-by: Hugh Dickins <hugh@...itas.com>
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
---
Index: mmotm-2.6.29-Mar11/mm/page_cgroup.c
===================================================================
--- mmotm-2.6.29-Mar11.orig/mm/page_cgroup.c
+++ mmotm-2.6.29-Mar11/mm/page_cgroup.c
@@ -426,13 +426,6 @@ int swap_cgroup_swapon(int type, unsigne
 	}
 	mutex_unlock(&swap_cgroup_mutex);
 
-	printk(KERN_INFO
-		"swap_cgroup: uses %ld bytes of vmalloc for pointer array space"
-		" and %ld bytes to hold mem_cgroup information per swap ents\n",
-		array_size, length * PAGE_SIZE);
-	printk(KERN_INFO
-	"swap_cgroup can be disabled by noswapaccount boot option.\n");
-
 	return 0;
 nomem:
 	printk(KERN_INFO "couldn't allocate enough memory for swap_cgroup.\n");
Index: mmotm-2.6.29-Mar11/init/Kconfig
===================================================================
--- mmotm-2.6.29-Mar11.orig/init/Kconfig
+++ mmotm-2.6.29-Mar11/init/Kconfig
@@ -603,6 +603,8 @@ config CGROUP_MEM_RES_CTLR_SWAP
 	  is disabled by boot option, this will be automatically disabled and
 	  there will be no overhead from this. Even when you set this config=y,
 	  if boot option "noswapaccount" is set, swap will not be accounted.
+	  Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
+	  size is 4096bytes, 512k per 1Gbytes of swap.
 
 endif # CGROUPS
 

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