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From: "Américo Wang" <xiyou.wangcong@gmail.com>
To: Pintu Agarwal <pintu_agarwal@yahoo.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Eric Dumazet <eric.dumazet@gmail.com>,
	Changli Gao <xiaosuo@gmail.com>, Jiri Slaby <jslaby@suse.cz>,
	azurIt <azurit@pobox.sk>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	linux-fsdevel@vger.kernel.org, Jiri Slaby <jirislaby@gmail.com>
Subject: Re: Regarding memory fragmentation using malloc....
Date: Wed, 13 Apr 2011 19:44:39 +0800	[thread overview]
Message-ID: <BANLkTi=7KHMA_JOwQcMQj5M+XU=qO07s2g@mail.gmail.com> (raw)
In-Reply-To: <530486.50523.qm@web162020.mail.bf1.yahoo.com>

On Wed, Apr 13, 2011 at 2:54 PM, Pintu Agarwal <pintu_agarwal@yahoo.com> wrote:
> Dear All,
>
> I am trying to understand how memory fragmentation occurs in linux using many malloc calls.
> I am trying to reproduce the page fragmentation problem in linux 2.6.29.x on a linux mobile(without Swap) using a small malloc(in loop) test program of BLOCK_SIZE (64*(4*K)).
> And then monitoring the page changes in /proc/buddyinfo after each operation.
> From the output I can see that the page values under buddyinfo keeps changing. But I am not able to relate these changes with my malloc BLOCK_SIZE.
> I mean with my BLOCK_SIZE of (2^6 x 4K ==> 2^6 PAGES) the 2^6 th block under /proc/buddyinfo should change. But this is not the actual behaviour.
> Whatever is the blocksize, the buddyinfo changes only for 2^0 or 2^1 or 2^2 or 2^3.
>
> I am trying to measure the level of fragmentation after each page allocation.
> Can somebody explain me in detail, how actually /proc/buddyinfo changes after each allocation and deallocation.
>

What malloc() sees is virtual memory of the process, while buddyinfo
shows physical memory pages.

When you malloc() 64K memory, the kernel may not allocate a 64K
physical memory at one time
for you.

Thanks.

  reply	other threads:[~2011-04-13 11:44 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-03-15 13:25 Regression from 2.6.36 azurIt
2011-03-17  0:15 ` Greg KH
2011-03-17  0:53   ` Dave Jones
2011-03-17 13:30     ` azurIt
2011-04-07 10:01   ` azurIt
2011-04-07 10:19     ` Jiri Slaby
2011-04-07 11:21       ` Américo Wang
2011-04-07 11:57         ` Eric Dumazet
2011-04-07 12:13           ` Eric Dumazet
2011-04-07 15:27             ` Changli Gao
2011-04-07 15:36               ` Eric Dumazet
2011-04-12 22:49                 ` Andrew Morton
2011-04-13  1:23                   ` Changli Gao
2011-04-13  1:31                     ` Andrew Morton
2011-04-13  2:37                       ` Eric Dumazet
2011-04-13  6:54                         ` Regarding memory fragmentation using malloc Pintu Agarwal
2011-04-13 11:44                           ` Américo Wang [this message]
2011-04-13 13:56                             ` Pintu Agarwal
2011-04-13 15:25                               ` Michal Nazarewicz
2011-04-14  6:44                                 ` Pintu Agarwal
2011-04-14 10:47                                   ` Michal Nazarewicz
2011-04-14 12:24                                     ` Pintu Agarwal
2011-04-14 12:31                                       ` Michal Nazarewicz
2011-04-13 21:16                         ` Regression from 2.6.36 Andrew Morton
2011-04-13 21:24                           ` Andrew Morton
2011-04-19 19:29                             ` azurIt
2011-04-19 19:55                               ` Andrew Morton
2011-04-13 21:44                           ` David Rientjes
2011-04-13 21:54                             ` Andrew Morton
2011-04-14  2:10                           ` Eric Dumazet
2011-04-14  5:28                             ` Andrew Morton
2011-04-14  6:31                               ` Eric Dumazet
2011-04-14  9:08                                 ` azurIt
2011-04-14 10:27                                   ` Eric Dumazet
2011-04-14 10:31                                     ` azurIt
2011-04-14 10:25                           ` Mel Gorman
2011-04-15  9:59                             ` azurIt
2011-04-15 10:47                               ` Mel Gorman
2011-04-15 10:56                                 ` azurIt
2011-04-15 11:17                                   ` Mel Gorman
2011-04-15 11:36                                     ` azurIt
2011-04-15 13:01                                       ` Mel Gorman
2011-04-15 13:21                                         ` azurIt
2011-04-15 14:15                                           ` Mel Gorman
2011-04-08 12:25               ` azurIt

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