From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2DC8EC83004 for ; Wed, 29 Apr 2020 13:37:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0EDCB206D6 for ; Wed, 29 Apr 2020 13:37:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="j+YR/UrI" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727863AbgD2Nha (ORCPT ); Wed, 29 Apr 2020 09:37:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52972 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727106AbgD2NhB (ORCPT ); Wed, 29 Apr 2020 09:37:01 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2A2BCC0A3BF2; Wed, 29 Apr 2020 06:37:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender :Reply-To:Content-Type:Content-ID:Content-Description; bh=SsJU8G69T3VOptzLNj4acuU2/UPgVlbaEW38OX0+2cU=; b=j+YR/UrI4nDEFJueHFDMNgZdyj xfQn/iZ63FmIU2xyKvPqd4CbZU9PiJ2GndB/1KNRVLnUl0lPtDijN01I8Z/OBfVNIQhaqJYm6Wudu jvZlbpK8eh9LTo+HiMbWLMFX5U0Gkng3W3idxSb/72r3QR3u/SKKbKrNyvZ0s13taNO8d5UZw+vma U/nvPNhsn1a59Jo9IfWhsJbuVXVBSsiWZ1oKKQhpx8QhLU21P4lxMRBFYLLv6vp29l3XT60e61m2T /Bd22G0Q1fQEl5EcR2FrtlhIt7xYD68IxOmq6eWwBUaqFSgkKJN6gf7Qcq1qW2YN+QHk/ew70YZQN dyu8pmPA==; Received: from willy by bombadil.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1jTmtX-0005wp-W7; Wed, 29 Apr 2020 13:36:59 +0000 From: Matthew Wilcox To: linux-fsdevel@vger.kernel.org Cc: "Matthew Wilcox (Oracle)" , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 24/25] mm: Add large page readahead Date: Wed, 29 Apr 2020 06:36:56 -0700 Message-Id: <20200429133657.22632-25-willy@infradead.org> X-Mailer: git-send-email 2.21.1 In-Reply-To: <20200429133657.22632-1-willy@infradead.org> References: <20200429133657.22632-1-willy@infradead.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Matthew Wilcox (Oracle)" If the filesystem supports large pages, allocate larger pages in the readahead code when it seems worth doing. The heuristic for choosing larger page sizes will surely need some tuning, but this aggressive ramp-up seems good for testing. Signed-off-by: Matthew Wilcox (Oracle) --- mm/readahead.c | 93 ++++++++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 87 insertions(+), 6 deletions(-) diff --git a/mm/readahead.c b/mm/readahead.c index 74c7e1eff540..e2493189e832 100644 --- a/mm/readahead.c +++ b/mm/readahead.c @@ -149,7 +149,7 @@ static void read_pages(struct readahead_control *rac, struct list_head *pages, blk_finish_plug(&plug); - BUG_ON(!list_empty(pages)); + BUG_ON(pages && !list_empty(pages)); BUG_ON(readahead_count(rac)); out: @@ -428,13 +428,92 @@ static int try_context_readahead(struct address_space *mapping, return 1; } +#ifdef CONFIG_TRANSPARENT_HUGEPAGE +static inline int ra_alloc_page(struct readahead_control *rac, pgoff_t index, + pgoff_t mark, unsigned int order, gfp_t gfp) +{ + int err; + struct page *page = __page_cache_alloc_order(gfp, order); + + if (!page) + return -ENOMEM; + if (mark - index < (1UL << order)) + SetPageReadahead(page); + err = add_to_page_cache_lru(page, rac->mapping, index, gfp); + if (err) + put_page(page); + else + rac->_nr_pages += 1UL << order; + return err; +} + +static bool page_cache_readahead_order(struct readahead_control *rac, + struct file_ra_state *ra, unsigned int order) +{ + struct address_space *mapping = rac->mapping; + unsigned int old_order = order; + pgoff_t index = readahead_index(rac); + pgoff_t limit = (i_size_read(mapping->host) - 1) >> PAGE_SHIFT; + pgoff_t mark = index + ra->size - ra->async_size; + int err = 0; + gfp_t gfp = readahead_gfp_mask(mapping); + + if (!(mapping->host->i_sb->s_type->fs_flags & FS_LARGE_PAGES)) + return false; + + limit = min(limit, index + ra->size - 1); + + /* Grow page size up to PMD size */ + if (order < HPAGE_PMD_ORDER) { + order += 2; + if (order > HPAGE_PMD_ORDER) + order = HPAGE_PMD_ORDER; + while ((1 << order) > ra->size) + order--; + } + + /* If size is somehow misaligned, fill with order-0 pages */ + while (!err && index & ((1UL << old_order) - 1)) + err = ra_alloc_page(rac, index++, mark, 0, gfp); + + while (!err && index & ((1UL << order) - 1)) { + err = ra_alloc_page(rac, index, mark, old_order, gfp); + index += 1UL << old_order; + } + + while (!err && index <= limit) { + err = ra_alloc_page(rac, index, mark, order, gfp); + index += 1UL << order; + } + + if (index > limit) { + ra->size += index - limit - 1; + ra->async_size += index - limit - 1; + } + + read_pages(rac, NULL, false); + + /* + * If there were already pages in the page cache, then we may have + * left some gaps. Let the regular readahead code take care of this + * situation. + */ + return !err; +} +#else +static bool page_cache_readahead_order(struct readahead_control *rac, + struct file_ra_state *ra, unsigned int order) +{ + return false; +} +#endif + /* * A minimal readahead algorithm for trivial sequential/random reads. */ static void ondemand_readahead(struct address_space *mapping, struct file_ra_state *ra, struct file *file, - bool hit_readahead_marker, pgoff_t index, - unsigned long req_size) + struct page *page, pgoff_t index, unsigned long req_size) { DEFINE_READAHEAD(rac, file, mapping, index); struct backing_dev_info *bdi = inode_to_bdi(mapping->host); @@ -473,7 +552,7 @@ static void ondemand_readahead(struct address_space *mapping, * Query the pagecache for async_size, which normally equals to * readahead size. Ramp it up and use it as the new readahead size. */ - if (hit_readahead_marker) { + if (page) { pgoff_t start; rcu_read_lock(); @@ -544,6 +623,8 @@ static void ondemand_readahead(struct address_space *mapping, } rac._index = ra->start; + if (page && page_cache_readahead_order(&rac, ra, compound_order(page))) + return; __do_page_cache_readahead(&rac, ra->size, ra->async_size); } @@ -578,7 +659,7 @@ void page_cache_sync_readahead(struct address_space *mapping, } /* do read-ahead */ - ondemand_readahead(mapping, ra, filp, false, index, req_count); + ondemand_readahead(mapping, ra, filp, NULL, index, req_count); } EXPORT_SYMBOL_GPL(page_cache_sync_readahead); @@ -624,7 +705,7 @@ page_cache_async_readahead(struct address_space *mapping, return; /* do read-ahead */ - ondemand_readahead(mapping, ra, filp, true, index, req_count); + ondemand_readahead(mapping, ra, filp, page, index, req_count); } EXPORT_SYMBOL_GPL(page_cache_async_readahead); -- 2.26.2