From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx174.postini.com [74.125.245.174]) by kanga.kvack.org (Postfix) with SMTP id EBE796B0031 for ; Mon, 2 Sep 2013 06:53:32 -0400 (EDT) From: "Kirill A. Shutemov" In-Reply-To: <1377883120-5280-3-git-send-email-n-horiguchi@ah.jp.nec.com> References: <1377883120-5280-1-git-send-email-n-horiguchi@ah.jp.nec.com> <1377883120-5280-3-git-send-email-n-horiguchi@ah.jp.nec.com> Subject: RE: [PATCH 2/2] thp: support split page table lock Content-Transfer-Encoding: 7bit Message-Id: <20130902105327.AE4D4E0090@blue.fi.intel.com> Date: Mon, 2 Sep 2013 13:53:27 +0300 (EEST) Sender: owner-linux-mm@kvack.org List-ID: To: Naoya Horiguchi Cc: linux-mm@kvack.org, Andrew Morton , Mel Gorman , Andi Kleen , Michal Hocko , KOSAKI Motohiro , Rik van Riel , Andrea Arcangeli , kirill.shutemov@linux.intel.com, "Aneesh Kumar K.V" , Alex Thorlton , linux-kernel@vger.kernel.org Naoya Horiguchi wrote: > Thp related code also uses per process mm->page_table_lock now. So making > it fine-grained can provide better performance. > > This patch makes thp support split page table lock which makes us use > page->ptl of the pages storing "pmd_trans_huge" pmds. Hm. So, you use page->ptl only when you deal with thp pages, otherwise mm->page_table_lock, right? It looks inconsistent to me. Does it mean we have to take both locks on split and collapse paths? I'm not sure if it's safe to take only page->ptl for alloc path. Probably not. Why not to use new locking for pmd everywhere? -- Kirill A. Shutemov -- 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: email@kvack.org