Re: [LSF/MM TOPIC] Non standard size THP

2019-02-13 Thread Anshuman Khandual
On 02/13/2019 07:08 PM, Michal Hocko wrote: > On Wed 13-02-19 18:20:03, Anshuman Khandual wrote: >> On 02/12/2019 02:03 PM, Kirill A. Shutemov wrote: >>> Honestly, I'm very skeptical about the idea. It took a lot of time to >>> stabilize THP for singe page size, equal to PMD page table, but

Re: [LSF/MM TOPIC] Non standard size THP

2019-02-13 Thread Kirill A. Shutemov
On Wed, Feb 13, 2019 at 06:20:03PM +0530, Anshuman Khandual wrote: > > > On 02/12/2019 02:03 PM, Kirill A. Shutemov wrote: > > On Fri, Feb 08, 2019 at 07:43:57AM +0530, Anshuman Khandual wrote: > >> Hello, > >> > >> THP is currently supported for > >> > >> - PMD level pages (anon and file) > >>

Re: [LSF/MM TOPIC] Non standard size THP

2019-02-13 Thread Michal Hocko
On Wed 13-02-19 18:20:03, Anshuman Khandual wrote: > On 02/12/2019 02:03 PM, Kirill A. Shutemov wrote: > > Honestly, I'm very skeptical about the idea. It took a lot of time to > > stabilize THP for singe page size, equal to PMD page table, but this looks > > like a new can of worms. :P > > I

Re: [LSF/MM TOPIC] Non standard size THP

2019-02-13 Thread Kirill A. Shutemov
On Wed, Feb 13, 2019 at 05:06:47AM -0800, Matthew Wilcox wrote: > On Tue, Feb 12, 2019 at 11:33:31AM +0300, Kirill A. Shutemov wrote: > > To consider it seriously we need to understand what it means for > > split_huge_p?d()/split_huge_page()? How khugepaged will deal with this? > > > > In

Re: [LSF/MM TOPIC] Non standard size THP

2019-02-13 Thread Matthew Wilcox
On Tue, Feb 12, 2019 at 11:33:31AM +0300, Kirill A. Shutemov wrote: > To consider it seriously we need to understand what it means for > split_huge_p?d()/split_huge_page()? How khugepaged will deal with this? > > In particular, I'm worry to expose (to user or CPU) page table state in > the middle

Re: [LSF/MM TOPIC] Non standard size THP

2019-02-13 Thread Anshuman Khandual
On 02/12/2019 02:03 PM, Kirill A. Shutemov wrote: > On Fri, Feb 08, 2019 at 07:43:57AM +0530, Anshuman Khandual wrote: >> Hello, >> >> THP is currently supported for >> >> - PMD level pages (anon and file) >> - PUD level pages (file - DAX file system) >> >> THP is a single entry mapping at

Re: [LSF/MM TOPIC] Non standard size THP

2019-02-12 Thread Kirill A. Shutemov
On Fri, Feb 08, 2019 at 07:43:57AM +0530, Anshuman Khandual wrote: > Hello, > > THP is currently supported for > > - PMD level pages (anon and file) > - PUD level pages (file - DAX file system) > > THP is a single entry mapping at standard page table levels (either PMD or > PUD) > > But

Re: [LSF/MM TOPIC] Non standard size THP

2019-02-07 Thread Anshuman Khandual
On 02/08/2019 09:54 AM, Matthew Wilcox wrote: > On Fri, Feb 08, 2019 at 07:43:57AM +0530, Anshuman Khandual wrote: >> How non-standard huge pages can be supported for THP >> >> - THP starts recognizing non standard huge page (exported by arch) like >> HPAGE_CONT_(PMD|PTE)_SIZE >> -

Re: [LSF/MM TOPIC] Non standard size THP

2019-02-07 Thread Matthew Wilcox
On Fri, Feb 08, 2019 at 07:43:57AM +0530, Anshuman Khandual wrote: > How non-standard huge pages can be supported for THP > > - THP starts recognizing non standard huge page (exported by arch) like > HPAGE_CONT_(PMD|PTE)_SIZE > - THP starts operating for either on HPAGE_PMD_SIZE or

[LSF/MM TOPIC] Non standard size THP

2019-02-07 Thread Anshuman Khandual
Hello, THP is currently supported for - PMD level pages (anon and file) - PUD level pages (file - DAX file system) THP is a single entry mapping at standard page table levels (either PMD or PUD) But architectures like ARM64 supports non-standard page table level huge pages with contiguous