From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Sat, 02 Oct 2004 18:30:15 +0900 (JST) Message-Id: <20041002.183015.41630389.taka@valinux.co.jp> Subject: Re: [RFC] memory defragmentation to satisfy high order allocations From: Hirokazu Takahashi In-Reply-To: <20041001234200.GA4635@logos.cnet> References: <20041001190430.GA4372@logos.cnet> <1096667823.3684.1299.camel@localhost> <20041001234200.GA4635@logos.cnet> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: marcelo.tosatti@cyclades.com Cc: haveblue@us.ibm.com, akpm@osdl.org, linux-mm@kvack.org, piggin@cyberone.com.au, arjanv@redhat.com, linux-kernel@vger.kernel.org List-ID: Hello, Marcelo. Generic memory defragmentation will be very nice for me to implement hugetlbpage migration, as allocating a new hugetlbpage is a hard job. > For the "defragmentation" operation we want to do an "easy" try - ie if we > can't remap giveup. > > I feel we should try to "untie" the code which checks for remapping availability / > does the remapping from the page migration - so to be able to share the most > code between it and other users of the same functionality. I think it's possible to introduce non-wait mode to the migration code, as you may expect. Shall I implement it? > Curiosity: How did you guys test the migration operation? Several threads on > several processors operating on the memory, etc? I always test it with the zone hotplug emulation patch, which Mr.Iwamoto has made. I usually run following jobs concurrently while zones are added and removed repeatedly on a SMP machine. - making linux kernel - copying file trees. - overwriting file trees. - removing file trees - some pages are swapped out automatically:) And Mr.Iwamoto has some small programs to check any kind of page can be migrated. The programs repeat one of following actions: - read/write files . - use MAP_SHARED and MAP_PRIVATE mmap()'s and read/write there. - use Direct I/O. - use AIO. - fork to have COW pages. - use shmem. - use sendfile. > Cool. I'll take a closer look at the relevant parts of memory hotplug patches > this weekend, hopefully. See if I can help with testing of these patches too. Any comments are very welcome. Thank you, Hirokazu Takahashi. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: aart@kvack.org