From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f172.google.com (mail-pd0-f172.google.com [209.85.192.172]) by kanga.kvack.org (Postfix) with ESMTP id 3A9186B035C for ; Mon, 21 Oct 2013 17:48:10 -0400 (EDT) Received: by mail-pd0-f172.google.com with SMTP id z10so9206300pdj.17 for ; Mon, 21 Oct 2013 14:48:09 -0700 (PDT) Received: from psmtp.com ([74.125.245.194]) by mx.google.com with SMTP id zl9si9672813pbc.24.2013.10.21.14.48.08 for ; Mon, 21 Oct 2013 14:48:09 -0700 (PDT) Received: by mail-pa0-f52.google.com with SMTP id kl14so8708341pab.11 for ; Mon, 21 Oct 2013 14:48:07 -0700 (PDT) Date: Mon, 21 Oct 2013 14:48:03 -0700 From: Ning Qu Subject: [PATCHv2 09/13] mm, thp, tmpfs: huge page support in do_shmem_file_read Message-ID: <20131021214803.GJ29870@hippobay.mtv.corp.google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: owner-linux-mm@kvack.org List-ID: To: Andrea Arcangeli , Andrew Morton , "Kirill A. Shutemov" , Hugh Dickins Cc: Al Viro , Wu Fengguang , Jan Kara , Mel Gorman , linux-mm@kvack.org, Andi Kleen , Matthew Wilcox , Hillf Danton , Dave Hansen , Alexander Shishkin , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Ning Qu , Ning Qu Support huge page in do_shmem_file_read when possible. Still have room to improve, since we re-search the page in page cache everytime, but for huge page, we might save some searches and reuse the huge page for the next read across page boundary. Signed-off-by: Ning Qu --- mm/shmem.c | 47 +++++++++++++++++++++++++++++++++-------------- 1 file changed, 33 insertions(+), 14 deletions(-) diff --git a/mm/shmem.c b/mm/shmem.c index f6829fd..1764a29 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1747,13 +1747,25 @@ shmem_write_end(struct file *file, struct address_space *mapping, return copied; } +static unsigned long page_cache_to_mask(struct page *page) +{ + if (page && PageTransHugeCache(page)) + return HPAGE_PMD_MASK; + else + return PAGE_CACHE_MASK; +} + +static unsigned long pos_to_off(struct page *page, loff_t pos) +{ + return pos & ~page_cache_to_mask(page); +} + static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor) { struct inode *inode = file_inode(filp); gfp_t gfp = mapping_gfp_mask(inode->i_mapping); struct address_space *mapping = inode->i_mapping; pgoff_t index; - unsigned long offset; enum sgp_type sgp = SGP_READ; /* @@ -1765,25 +1777,26 @@ static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_ sgp = SGP_DIRTY; index = *ppos >> PAGE_CACHE_SHIFT; - offset = *ppos & ~PAGE_CACHE_MASK; + i_split_down_read(inode); for (;;) { struct page *page = NULL; pgoff_t end_index; unsigned long nr, ret; loff_t i_size = i_size_read(inode); + int flags = AOP_FLAG_TRANSHUGE; end_index = i_size >> PAGE_CACHE_SHIFT; if (index > end_index) break; if (index == end_index) { nr = i_size & ~PAGE_CACHE_MASK; - if (nr <= offset) + if (nr <= pos_to_off(page, *ppos)) break; } desc->error = shmem_getpage(inode, index, &page, sgp, gfp, - 0, NULL); + flags, NULL); if (desc->error) { if (desc->error == -EINVAL) desc->error = 0; @@ -1796,18 +1809,25 @@ static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_ * We must evaluate after, since reads (unlike writes) * are called without i_mutex protection against truncate */ - nr = PAGE_CACHE_SIZE; i_size = i_size_read(inode); end_index = i_size >> PAGE_CACHE_SHIFT; + + nr = PAGE_CACHE_SIZE; + if (page && PageTransHugeCache(page)) { + index &= ~HPAGE_CACHE_INDEX_MASK; + end_index &= ~HPAGE_CACHE_INDEX_MASK; + nr = PAGE_CACHE_SIZE << compound_order(page); + } + if (index == end_index) { - nr = i_size & ~PAGE_CACHE_MASK; - if (nr <= offset) { + nr = ((i_size - 1) & ~page_cache_to_mask(page)) + 1; + if (nr <= pos_to_off(page, *ppos)) { if (page) page_cache_release(page); break; } } - nr -= offset; + nr = nr - pos_to_off(page, *ppos); if (page) { /* @@ -1820,7 +1840,7 @@ static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_ /* * Mark the page accessed if we read the beginning. */ - if (!offset) + if (!pos_to_off(page, *ppos)) mark_page_accessed(page); } else { page = ZERO_PAGE(0); @@ -1837,10 +1857,9 @@ static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_ * "pos" here (the actor routine has to update the user buffer * pointers and the remaining count). */ - ret = actor(desc, page, offset, nr); - offset += ret; - index += offset >> PAGE_CACHE_SHIFT; - offset &= ~PAGE_CACHE_MASK; + ret = actor(desc, page, pos_to_off(page, *ppos), nr); + *ppos += ret; + index = *ppos >> PAGE_CACHE_SHIFT; page_cache_release(page); if (ret != nr || !desc->count) @@ -1849,7 +1868,7 @@ static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_ cond_resched(); } - *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; + i_split_up_read(inode); file_accessed(filp); } -- 1.8.4 -- 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