Documentation/ABI/testing/sysfs-fs-f2fs | 7 +++ fs/f2fs/debug.c | 3 ++ fs/f2fs/f2fs.h | 14 +++++- fs/f2fs/file.c | 65 +++++++++++++++++++++++++ fs/f2fs/inode.c | 14 ++++++ fs/f2fs/shrinker.c | 27 ++++++++++ fs/f2fs/super.c | 1 + fs/f2fs/sysfs.c | 8 +++ include/uapi/linux/f2fs.h | 7 +++ 9 files changed, 145 insertions(+), 1 deletion(-)
If users clearly know which file-backed pages to reclaim in system view, they can use this ioctl() to register in advance and reclaim all at once later. To MM and others, I'd like to propose this API in F2FS only, since 1) the use-case is quite limited in Android at the moment. Once it's generall accepted with more use-cases, happy to propose a generic API such as fadvise. Please chime in, if there's any needs. 2) it's file-backed pages which requires to maintain the list of inode objects. I'm not sure this fits in MM tho, also happy to listen to any feedback. Jaegeuk Kim (2): f2fs: register inodes which is able to donate pages f2fs: add a sysfs entry to request donate file-backed pages Documentation/ABI/testing/sysfs-fs-f2fs | 7 +++ fs/f2fs/debug.c | 3 ++ fs/f2fs/f2fs.h | 14 +++++- fs/f2fs/file.c | 65 +++++++++++++++++++++++++ fs/f2fs/inode.c | 14 ++++++ fs/f2fs/shrinker.c | 27 ++++++++++ fs/f2fs/super.c | 1 + fs/f2fs/sysfs.c | 8 +++ include/uapi/linux/f2fs.h | 7 +++ 9 files changed, 145 insertions(+), 1 deletion(-) -- 2.48.0.rc2.279.g1de40edade-goog
On Fri, Jan 17, 2025 at 04:41:16PM +0000, Jaegeuk Kim wrote: > If users clearly know which file-backed pages to reclaim in system view, they > can use this ioctl() to register in advance and reclaim all at once later. > > To MM and others, > > I'd like to propose this API in F2FS only, since > 1) the use-case is quite limited in Android at the moment. Once it's generall > accepted with more use-cases, happy to propose a generic API such as fadvise. > Please chime in, if there's any needs. > > 2) it's file-backed pages which requires to maintain the list of inode objects. > I'm not sure this fits in MM tho, also happy to listen to any feedback. You didn't cc the patches to linux-mm, so that's a bad start. I don't understand how this is different from MADV_COLD. Please explain.
On 01/17, Matthew Wilcox wrote: > On Fri, Jan 17, 2025 at 04:41:16PM +0000, Jaegeuk Kim wrote: > > If users clearly know which file-backed pages to reclaim in system view, they > > can use this ioctl() to register in advance and reclaim all at once later. > > > > To MM and others, > > > > I'd like to propose this API in F2FS only, since > > 1) the use-case is quite limited in Android at the moment. Once it's generall > > accepted with more use-cases, happy to propose a generic API such as fadvise. > > Please chime in, if there's any needs. > > > > 2) it's file-backed pages which requires to maintain the list of inode objects. > > I'm not sure this fits in MM tho, also happy to listen to any feedback. > > You didn't cc the patches to linux-mm, so that's a bad start. Because #1. > > I don't understand how this is different from MADV_COLD. Please > explain. MADV_COLD is a vma range, while this is a file range. So, it's more close to fadvise(POSIX_FADV_DONTNEED) which tries to reclaim the file-backed pages at the time when it's called. The idea is to keep the hints only, and try to reclaim all later when admin expects system memory pressure soon.
On Fri, Jan 17, 2025 at 06:48:55PM +0000, Jaegeuk Kim wrote: > > I don't understand how this is different from MADV_COLD. Please > > explain. > > MADV_COLD is a vma range, while this is a file range. So, it's more close to > fadvise(POSIX_FADV_DONTNEED) which tries to reclaim the file-backed pages > at the time when it's called. The idea is to keep the hints only, and try to > reclaim all later when admin expects system memory pressure soon. So you're saying you want POSIX_FADV_COLD?
On 01/17, Matthew Wilcox wrote: > On Fri, Jan 17, 2025 at 06:48:55PM +0000, Jaegeuk Kim wrote: > > > I don't understand how this is different from MADV_COLD. Please > > > explain. > > > > MADV_COLD is a vma range, while this is a file range. So, it's more close to > > fadvise(POSIX_FADV_DONTNEED) which tries to reclaim the file-backed pages > > at the time when it's called. The idea is to keep the hints only, and try to > > reclaim all later when admin expects system memory pressure soon. > > So you're saying you want POSIX_FADV_COLD? Yeah, the intention looks similar like marking it cold and paging out later.
On 01/17, Jaegeuk Kim wrote: > On 01/17, Matthew Wilcox wrote: > > On Fri, Jan 17, 2025 at 06:48:55PM +0000, Jaegeuk Kim wrote: > > > > I don't understand how this is different from MADV_COLD. Please > > > > explain. > > > > > > MADV_COLD is a vma range, while this is a file range. So, it's more close to > > > fadvise(POSIX_FADV_DONTNEED) which tries to reclaim the file-backed pages > > > at the time when it's called. The idea is to keep the hints only, and try to > > > reclaim all later when admin expects system memory pressure soon. > > > > So you're saying you want POSIX_FADV_COLD? > > Yeah, the intention looks similar like marking it cold and paging out later. Kindly ping, for the feedback on the direction. If there's demand for something generalized api, I'm happy to explore.
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