Messages in this thread | | | Date | Thu, 4 Dec 2008 17:56:19 +0800 (CST) | From | peter meng <> | Subject | Re: question related page frame reclaim on embedded system |
| |
Hi,Kosaki
1. what happens if used IPC share memory ? As i knew IPC share memory use anonymous mapping ,but not sure my understand is correctly .
Thanks advanced . Best Regards. Peter
--- On Wed, 12/3/08, KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> wrote:
> From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> > Subject: Re: question related page frame reclaim on embedded system > To: mengsanshui@yahoo.com.cn > Cc: kosaki.motohiro@jp.fujitsu.com, linux-kernel@vger.kernel.org > Date: Wednesday, December 3, 2008, 9:48 AM > > > > Hi,Kosaki > > > > Thank you very much . > > I have another question about share memory . Assume a > process create a share memory , > > seems the page that the process used can not be > discard or swap out > > No. Linux can swap out COW shared memory too. see swap > cache related code. > Also, Linux can discard non-dirty and file mapped shared > page. > > but, yes. > Linux can't discart dirty or anonymous mapped page. > > > > when they are no longer used by any process or no swap > space . > > > > 1.whether the maped page of the share memory is > persistent in system until > > system restart ? if not how page frame reclaiming > process it ? > > No. > Linux manage page reference count. > forrk increment it. exit decrement it. > So, when process exiting, Linux can discard non used page > immediately. > > IOW, reclaim provide "page discard/swap although page > is still used" mechanism.
| |