From: Miaohe Lin <linmiaohe@huawei.com>
To: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: <hch@lst.de>, <kent.overstreet@gmail.com>,
<linux-fsdevel@vger.kernel.org>, <linux-mm@kvack.org>
Subject: Re: [PATCH v4 02/18] mm/filemap: Remove dynamically allocated array from filemap_read
Date: Fri, 22 Jan 2021 14:59:15 +0800 [thread overview]
Message-ID: <ce489afa-1621-947b-8cd6-b5c45eb5e2cc@huawei.com> (raw)
In-Reply-To: <20210121041616.3955703-3-willy@infradead.org>
Hi:
On 2021/1/21 12:16, Matthew Wilcox (Oracle) wrote:
> Increasing the batch size runs into diminishing returns. It's probably
> better to make, eg, three calls to filemap_get_pages() than it is to
> call into kmalloc().
>
LGTM. Thanks.
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> ---
> mm/filemap.c | 15 ++-------------
> 1 file changed, 2 insertions(+), 13 deletions(-)
>
> diff --git a/mm/filemap.c b/mm/filemap.c
> index 934e04f1760ef..5dec04c8e16b0 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -2421,8 +2421,8 @@ ssize_t generic_file_buffered_read(struct kiocb *iocb,
> struct file_ra_state *ra = &filp->f_ra;
> struct address_space *mapping = filp->f_mapping;
> struct inode *inode = mapping->host;
> - struct page *pages_onstack[PAGEVEC_SIZE], **pages = NULL;
> - unsigned int nr_pages = min_t(unsigned int, 512,
> + struct page *pages[PAGEVEC_SIZE];
> + unsigned int nr_pages = min_t(unsigned int, PAGEVEC_SIZE,
> ((iocb->ki_pos + iter->count + PAGE_SIZE - 1) >> PAGE_SHIFT) -
> (iocb->ki_pos >> PAGE_SHIFT));
> int i, pg_nr, error = 0;
> @@ -2433,14 +2433,6 @@ ssize_t generic_file_buffered_read(struct kiocb *iocb,
> return 0;
> iov_iter_truncate(iter, inode->i_sb->s_maxbytes);
>
> - if (nr_pages > ARRAY_SIZE(pages_onstack))
> - pages = kmalloc_array(nr_pages, sizeof(void *), GFP_KERNEL);
> -
> - if (!pages) {
> - pages = pages_onstack;
> - nr_pages = min_t(unsigned int, nr_pages, ARRAY_SIZE(pages_onstack));
> - }
> -
> do {
> cond_resched();
>
> @@ -2525,9 +2517,6 @@ ssize_t generic_file_buffered_read(struct kiocb *iocb,
>
> file_accessed(filp);
>
> - if (pages != pages_onstack)
> - kfree(pages);
> -
> return written ? written : error;
> }
> EXPORT_SYMBOL_GPL(generic_file_buffered_read);
>
next prev parent reply other threads:[~2021-01-22 7:00 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-21 4:15 [PATCH v4 00/18] Refactor generic_file_buffered_read Matthew Wilcox (Oracle)
2021-01-21 4:15 ` [PATCH v4 01/18] mm/filemap: Rename generic_file_buffered_read subfunctions Matthew Wilcox (Oracle)
2021-01-21 7:30 ` Christoph Hellwig
2021-01-21 8:23 ` Miaohe Lin
2021-01-21 4:16 ` [PATCH v4 02/18] mm/filemap: Remove dynamically allocated array from filemap_read Matthew Wilcox (Oracle)
2021-01-21 7:31 ` Christoph Hellwig
2021-01-22 6:59 ` Miaohe Lin [this message]
2021-01-21 4:16 ` [PATCH v4 03/18] mm/filemap: Convert filemap_get_pages to take a pagevec Matthew Wilcox (Oracle)
2021-01-21 7:31 ` Christoph Hellwig
2021-01-21 4:16 ` [PATCH v4 04/18] mm/filemap: Use head pages in generic_file_buffered_read Matthew Wilcox (Oracle)
2021-01-21 4:16 ` [PATCH v4 05/18] mm/filemap: Pass a sleep state to put_and_wait_on_page_locked Matthew Wilcox (Oracle)
2021-01-21 4:16 ` [PATCH v4 06/18] mm/filemap: Support readpage splitting a page Matthew Wilcox (Oracle)
2021-01-21 4:16 ` [PATCH v4 07/18] mm/filemap: Inline __wait_on_page_locked_async into caller Matthew Wilcox (Oracle)
2021-01-21 4:16 ` [PATCH v4 08/18] mm/filemap: Don't call ->readpage if IOCB_WAITQ is set Matthew Wilcox (Oracle)
2021-01-21 4:16 ` [PATCH v4 09/18] mm/filemap: Change filemap_read_page calling conventions Matthew Wilcox (Oracle)
2021-01-21 7:31 ` Christoph Hellwig
2021-01-21 4:16 ` [PATCH v4 10/18] mm/filemap: Change filemap_create_page " Matthew Wilcox (Oracle)
2021-01-21 4:16 ` [PATCH v4 11/18] mm/filemap: Convert filemap_update_page to return an errno Matthew Wilcox (Oracle)
2021-01-21 7:32 ` Christoph Hellwig
2021-01-21 4:16 ` [PATCH v4 12/18] mm/filemap: Move the iocb checks into filemap_update_page Matthew Wilcox (Oracle)
2021-01-21 4:16 ` [PATCH v4 13/18] mm/filemap: Add filemap_range_uptodate Matthew Wilcox (Oracle)
2021-01-21 7:32 ` Christoph Hellwig
2021-01-21 4:16 ` [PATCH v4 14/18] mm/filemap: Split filemap_readahead out of filemap_get_pages Matthew Wilcox (Oracle)
2021-01-21 7:33 ` Christoph Hellwig
2021-01-21 4:16 ` [PATCH v4 15/18] mm/filemap: Restructure filemap_get_pages Matthew Wilcox (Oracle)
2021-01-21 7:33 ` Christoph Hellwig
2021-01-21 4:16 ` [PATCH v4 16/18] mm/filemap: Don't relock the page after calling readpage Matthew Wilcox (Oracle)
2021-01-21 7:34 ` Christoph Hellwig
2021-01-21 4:16 ` [PATCH v4 17/18] mm/filemap: Rename generic_file_buffered_read to filemap_read Matthew Wilcox (Oracle)
2021-01-21 4:16 ` [PATCH v4 18/18] mm/filemap: Simplify generic_file_read_iter Matthew Wilcox (Oracle)
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