lkml.org 
[lkml]   [2019]   [Jun]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v3 0/6] Enable THP for text section of non-shmem files
[Cc fsdevel and lkml]

On Tue 18-06-19 23:24:18, Song Liu wrote:
> Changes v2 => v3:
> 1. Removed the limitation (cannot write to file with THP) by truncating
> whole file during sys_open (see 6/6);
> 2. Fixed a VM_BUG_ON_PAGE() in filemap_fault() (see 2/6);
> 3. Split function rename to a separate patch (Rik);
> 4. Updated condition in hugepage_vma_check() (Rik).
>
> Changes v1 => v2:
> 1. Fixed a missing mem_cgroup_commit_charge() for non-shmem case.
>
> 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. Original limitation #2 is removed in v3.
>
> 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!
>
> Song Liu (6):
> filemap: check compound_head(page)->mapping in filemap_fault()
> filemap: update offset check in filemap_fault()
> mm,thp: stats for file backed THP
> khugepaged: rename collapse_shmem() and khugepaged_scan_shmem()
> mm,thp: add read-only THP support for (non-shmem) FS
> mm,thp: handle writes to file with THP in pagecache
>
> fs/inode.c | 3 ++
> fs/proc/meminfo.c | 4 ++
> include/linux/fs.h | 31 ++++++++++++
> include/linux/mmzone.h | 2 +
> mm/Kconfig | 11 +++++
> mm/filemap.c | 9 ++--
> mm/khugepaged.c | 104 +++++++++++++++++++++++++++++++++--------
> mm/rmap.c | 12 +++--
> mm/truncate.c | 7 ++-
> mm/vmstat.c | 2 +
> 10 files changed, 156 insertions(+), 29 deletions(-)
>
> --
> 2.17.1

--
Michal Hocko
SUSE Labs

\
 
 \ /
  Last update: 2019-06-19 08:52    [W:0.037 / U:2.132 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site