From patchwork Thu Sep 15 11:55:00 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Kirill A . Shutemov" X-Patchwork-Id: 9333447 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 7A3B26077F for ; Thu, 15 Sep 2016 12:09:14 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 686C82969F for ; Thu, 15 Sep 2016 12:09:14 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 5D379296A3; Thu, 15 Sep 2016 12:09:14 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id E1BB12969F for ; Thu, 15 Sep 2016 12:09:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934126AbcIOLzo (ORCPT ); Thu, 15 Sep 2016 07:55:44 -0400 Received: from mga09.intel.com ([134.134.136.24]:40135 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756136AbcIOLzl (ORCPT ); Thu, 15 Sep 2016 07:55:41 -0400 Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga102.jf.intel.com with ESMTP; 15 Sep 2016 04:55:40 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.30,339,1470726000"; d="scan'208";a="1040321636" Received: from black.fi.intel.com ([10.237.72.56]) by fmsmga001.fm.intel.com with ESMTP; 15 Sep 2016 04:55:36 -0700 Received: by black.fi.intel.com (Postfix, from userid 1000) id DA7F1842; Thu, 15 Sep 2016 14:55:26 +0300 (EEST) From: "Kirill A. Shutemov" To: "Theodore Ts'o" , Andreas Dilger , Jan Kara , Andrew Morton Cc: Alexander Viro , Hugh Dickins , Andrea Arcangeli , Dave Hansen , Vlastimil Babka , Matthew Wilcox , Ross Zwisler , linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-block@vger.kernel.org, "Kirill A. Shutemov" Subject: [PATCHv3 18/41] HACK: readahead: alloc huge pages, if allowed Date: Thu, 15 Sep 2016 14:55:00 +0300 Message-Id: <20160915115523.29737-19-kirill.shutemov@linux.intel.com> X-Mailer: git-send-email 2.9.3 In-Reply-To: <20160915115523.29737-1-kirill.shutemov@linux.intel.com> References: <20160915115523.29737-1-kirill.shutemov@linux.intel.com> Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Most page cache allocation happens via readahead (sync or async), so if we want to have significant number of huge pages in page cache we need to find a ways to allocate them from readahead. Unfortunately, huge pages doesn't fit into current readahead design: 128 max readahead window, assumption on page size, PageReadahead() to track hit/miss. I haven't found a ways to get it right yet. This patch just allocates huge page if allowed, but doesn't really provide any readahead if huge page is allocated. We read out 2M a time and I would expect spikes in latancy without readahead. Therefore HACK. Having that said, I don't think it should prevent huge page support to be applied. Future will show if lacking readahead is a big deal with huge pages in page cache. Any suggestions are welcome. Signed-off-by: Kirill A. Shutemov --- mm/readahead.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff --git a/mm/readahead.c b/mm/readahead.c index c8a955b1297e..f46a9080f6a9 100644 --- a/mm/readahead.c +++ b/mm/readahead.c @@ -174,6 +174,21 @@ int __do_page_cache_readahead(struct address_space *mapping, struct file *filp, if (page_offset > end_index) break; + if (IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE) && + (!page_idx || !(page_offset % HPAGE_PMD_NR)) && + page_cache_allow_huge(mapping, page_offset)) { + page = __page_cache_alloc_order(gfp_mask | __GFP_COMP, + HPAGE_PMD_ORDER); + if (page) { + prep_transhuge_page(page); + page->index = round_down(page_offset, + HPAGE_PMD_NR); + list_add(&page->lru, &page_pool); + ret++; + goto start_io; + } + } + rcu_read_lock(); page = radix_tree_lookup(&mapping->page_tree, page_offset); rcu_read_unlock(); @@ -189,7 +204,7 @@ int __do_page_cache_readahead(struct address_space *mapping, struct file *filp, SetPageReadahead(page); ret++; } - +start_io: /* * Now start the IO. We ignore I/O errors - if the page is not * uptodate then the caller will launch readpage again, and