From: Andrea Arcangeli <aarcange@redhat.com>
To: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Jan Kara <jack@suse.cz>, Theodore Ts'o <tytso@mit.edu>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Andreas Dilger <adilger.kernel@dilger.ca>,
Jan Kara <jack@suse.com>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Hugh Dickins <hughd@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
Dave Hansen <dave.hansen@intel.com>,
Vlastimil Babka <vbabka@suse.cz>,
Matthew Wilcox <willy@infradead.org>,
Ross Zwisler <ross.zwisler@linux.intel.com>,
linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
linux-block@vger.kernel.org
Subject: Re: [PATCHv1, RFC 00/33] ext4: support of huge pages
Date: Wed, 27 Jul 2016 16:09:38 +0200 [thread overview]
Message-ID: <20160727140938.lsvn6c7pwbodkeio@redhat.com> (raw)
In-Reply-To: <20160727103335.GE11776@node.shutemov.name>
Hello,
On Wed, Jul 27, 2016 at 01:33:35PM +0300, Kirill A. Shutemov wrote:
> I guess you can get work 64k blocks with 4k pages if you *always* allocate
> order-4 pages for page cache of the filesystem. But I don't think it's
> sustainable. It's significant pressure on buddy allocator and compaction.
Agreed.
To guarantee compaction to succeed for a certain percentage of the RAM
kernelcore= would need to be used, but the bigger the movable zone is,
the bigger the imbalance will be, because the memory used by the
kernel cannot use the RAM that is in the movable zone. If the movable
zone is too big, early OOM failures may materialize where the kernel
hits OOM despite there's plenty of free memory in the movable zone.
So it's not ideal.
> I guess the right approach would a mechanism to scatter one block to
> multiple order-0 pages. At least for fallback.
That would be ideal to avoid having to mess with kernelcore=, because
no matter what direct compaction does (and current direction
compaction defaults wouldn't be aggressive enough anyway), without
kernelcore= the THP (or order4) allocation can fail at times.
THP always requires a fallback so that a compaction failure isn't
fatal and it can actually be fixed up later by khugepaged as more free
memory becomes available at runtime.
Thanks,
Andrea
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next prev parent reply other threads:[~2016-07-27 14:09 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-26 0:35 Kirill A. Shutemov
2016-07-26 0:35 ` [PATCHv1, RFC 01/33] tools: Add WARN_ON_ONCE Kirill A. Shutemov
2016-07-26 0:35 ` [PATCHv1, RFC 02/33] radix tree test suite: Allow GFP_ATOMIC allocations to fail Kirill A. Shutemov
2016-07-26 0:35 ` [PATCHv1, RFC 03/33] radix-tree: Add radix_tree_join Kirill A. Shutemov
2016-07-26 0:35 ` [PATCHv1, RFC 04/33] radix-tree: Add radix_tree_split Kirill A. Shutemov
2016-07-26 0:35 ` [PATCHv1, RFC 05/33] radix-tree: Add radix_tree_split_preload() Kirill A. Shutemov
2016-07-26 0:35 ` [PATCHv1, RFC 06/33] radix-tree: Handle multiorder entries being deleted by replace_clear_tags Kirill A. Shutemov
2016-07-26 0:35 ` [PATCHv1, RFC 07/33] mm, shmem: swich huge tmpfs to multi-order radix-tree entries Kirill A. Shutemov
2016-07-26 0:35 ` [PATCHv1, RFC 08/33] Revert "radix-tree: implement radix_tree_maybe_preload_order()" Kirill A. Shutemov
2016-07-26 0:35 ` [PATCHv1, RFC 09/33] page-flags: relax page flag poliry for PG_error and PG_writeback Kirill A. Shutemov
2016-07-26 0:35 ` [PATCHv1, RFC 10/33] mm, rmap: account file thp pages Kirill A. Shutemov
2016-07-26 0:35 ` [PATCHv1, RFC 11/33] thp: allow splitting non-shmem file-backed THPs Kirill A. Shutemov
2016-07-26 0:35 ` [PATCHv1, RFC 12/33] truncate: make sure invalidate_mapping_pages() can discard huge pages Kirill A. Shutemov
2016-07-26 0:35 ` [PATCHv1, RFC 13/33] filemap: allocate huge page in page_cache_read(), if allowed Kirill A. Shutemov
2016-07-26 0:35 ` [PATCHv1, RFC 14/33] filemap: handle huge pages in do_generic_file_read() Kirill A. Shutemov
2016-07-26 0:35 ` [PATCHv1, RFC 15/33] filemap: allocate huge page in pagecache_get_page(), if allowed Kirill A. Shutemov
2016-07-26 0:35 ` [PATCHv1, RFC 16/33] filemap: handle huge pages in filemap_fdatawait_range() Kirill A. Shutemov
2016-07-26 0:35 ` [PATCHv1, RFC 17/33] HACK: readahead: alloc huge pages, if allowed Kirill A. Shutemov
2016-07-26 0:35 ` [PATCHv1, RFC 18/33] HACK: block: bump BIO_MAX_PAGES Kirill A. Shutemov
2016-07-26 0:35 ` [PATCHv1, RFC 19/33] mm: make write_cache_pages() work on huge pages Kirill A. Shutemov
2016-07-26 0:35 ` [PATCHv1, RFC 20/33] thp: introduce hpage_size() and hpage_mask() Kirill A. Shutemov
2016-07-26 0:35 ` [PATCHv1, RFC 21/33] fs: make block_read_full_page() be able to read huge page Kirill A. Shutemov
2016-07-26 0:35 ` [PATCHv1, RFC 22/33] fs: make block_write_{begin,end}() be able to handle huge pages Kirill A. Shutemov
2016-07-26 0:35 ` [PATCHv1, RFC 23/33] fs: make block_page_mkwrite() aware about " Kirill A. Shutemov
2016-07-26 0:35 ` [PATCHv1, RFC 24/33] truncate: make truncate_inode_pages_range() " Kirill A. Shutemov
2016-07-26 0:35 ` [PATCHv1, RFC 25/33] ext4: make ext4_mpage_readpages() hugepage-aware Kirill A. Shutemov
2016-07-26 0:35 ` [PATCHv1, RFC 26/33] ext4: make ext4_writepage() work on huge pages Kirill A. Shutemov
2016-07-26 0:35 ` [PATCHv1, RFC 27/33] ext4: handle huge pages in ext4_page_mkwrite() Kirill A. Shutemov
2016-07-26 0:35 ` [PATCHv1, RFC 28/33] ext4: handle huge pages in __ext4_block_zero_page_range() Kirill A. Shutemov
2016-07-26 0:35 ` [PATCHv1, RFC 29/33] ext4: handle huge pages in ext4_da_write_end() Kirill A. Shutemov
2016-07-26 0:35 ` [PATCHv1, RFC 30/33] ext4: relax assert in ext4_da_page_release_reservation() Kirill A. Shutemov
2016-07-26 0:35 ` [PATCHv1, RFC 31/33] WIP: ext4: handle writeback with huge pages Kirill A. Shutemov
2016-07-26 0:35 ` [PATCHv1, RFC 32/33] mm, fs, ext4: expand use of page_mapping() and page_to_pgoff() Kirill A. Shutemov
2016-07-26 0:35 ` [PATCHv1, RFC 33/33] ext4, vfs: add huge= mount option Kirill A. Shutemov
2016-07-26 17:29 ` [PATCHv1, RFC 00/33] ext4: support of huge pages Theodore Ts'o
2016-07-26 19:12 ` Kirill A. Shutemov
2016-07-27 9:17 ` Jan Kara
2016-07-27 10:33 ` Kirill A. Shutemov
2016-07-27 14:09 ` Andrea Arcangeli [this message]
2016-08-10 0:54 ` [PATCH] mm, hugetlb: switch hugetlbfs to multi-order radix-tree entries Naoya Horiguchi
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