From: Song Liu <songliubraving@fb.com> To: <linux-mm@kvack.org> Cc: <matthew.wilcox@oracle.com>, <kirill.shutemov@linux.intel.com>, <kernel-team@fb.com>, <william.kucharski@oracle.com>, <chad.mynhier@oracle.com>, <mike.kravetz@oracle.com>, Song Liu <songliubraving@fb.com> Subject: [PATCH v2 0/3] Enable THP for text section of non-shmem files Date: Fri, 14 Jun 2019 11:22:01 -0700 Message-ID: <20190614182204.2673660-1-songliubraving@fb.com> (raw) This set follows up discussion at LSF/MM 2019. The motivation is to put text section of an application in THP, and thus reduces iTLB miss rate and improves performance. Both Facebook and Oracle showed strong interests to this feature. To make reviews easier, this set aims a mininal valid product. Current version of the work does not have any changes to file system specific code. This comes with some limitations (discussed later). This set enables an application to "hugify" its text section by simply running something like: madvise(0x600000, 0x80000, MADV_HUGEPAGE); Before this call, the /proc/<pid>/maps looks like: 00400000-074d0000 r-xp 00000000 00:27 2006927 app After this call, part of the text section is split out and mapped to THP: 00400000-00425000 r-xp 00000000 00:27 2006927 app 00600000-00e00000 r-xp 00200000 00:27 2006927 app <<< on THP 00e00000-074d0000 r-xp 00a00000 00:27 2006927 app Limitations: 1. This only works for text section (vma with VM_DENYWRITE). 2. Once the application put its own pages in THP, the file is read only. open(file, O_WRITE) will fail with -ETXTBSY. To modify/update the file, it must be removed first. Here is an example case: root@virt-test:~/# ./app hugify ^C root@virt-test:~/# dd if=/dev/zero of=./app bs=1k count=2 dd: failed to open './app': Text file busy root@virt-test:~/# cp app.backup app cp: cannot create regular file 'app': Text file busy root@virt-test:~/# rm app root@virt-test:~/# cp app.backup app root@virt-test:~/# We gated this feature with an experimental config, READ_ONLY_THP_FOR_FS. Once we get better support on the write path, we can remove the config and enable it by default. Tested cases: 1. Tested with btrfs and ext4. 2. Tested with real work application (memcache like caching service). 3. Tested with "THP aware uprobe": https://patchwork.kernel.org/project/linux-mm/list/?series=131339 Please share your comments and suggestions on this. Thanks! Changes v1 => v2: 1. Fixed a missing mem_cgroup_commit_charge() for non-shmem case. Song Liu (3): mm: check compound_head(page)->mapping in filemap_fault() mm,thp: stats for file backed THP mm,thp: add read-only THP support for (non-shmem) FS fs/proc/meminfo.c | 4 ++ include/linux/fs.h | 8 ++++ include/linux/mmzone.h | 2 + mm/Kconfig | 11 +++++ mm/filemap.c | 7 +-- mm/khugepaged.c | 106 +++++++++++++++++++++++++++++++++-------- mm/rmap.c | 12 +++-- mm/vmstat.c | 2 + 8 files changed, 125 insertions(+), 27 deletions(-) -- 2.17.1
next reply index Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-06-14 18:22 Song Liu [this message] 2019-06-14 18:22 ` [PATCH v2 1/3] mm: check compound_head(page)->mapping in filemap_fault() Song Liu 2019-06-17 14:59 ` Rik van Riel 2019-06-14 18:22 ` [PATCH v2 2/3] mm,thp: stats for file backed THP Song Liu 2019-06-17 15:00 ` Rik van Riel 2019-06-21 12:50 ` Kirill A. Shutemov 2019-06-21 14:09 ` Song Liu 2019-06-14 18:22 ` [PATCH v2 3/3] mm,thp: add read-only THP support for (non-shmem) FS Song Liu 2019-06-17 15:42 ` Rik van Riel 2019-06-21 12:58 ` Kirill A. Shutemov 2019-06-21 13:08 ` Song Liu 2019-06-21 13:11 ` Kirill A. Shutemov 2019-06-18 21:12 ` [PATCH v2 0/3] Enable THP for text section of non-shmem files Andrew Morton 2019-06-18 21:48 ` Song Liu 2019-06-20 1:13 ` Andrew Morton 2019-06-20 2:04 ` Song Liu 2019-06-19 6:26 ` Song Liu
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