[lkml]   [2017]   [Oct]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [RFC PATCH 0/3] Add mmap(MAP_CONTIG) support
On 10/12/2017 07:16 AM, Mike Kravetz wrote:
> The following is a 'possible' way to add such functionality. I just
> did what was easy and pre-allocated contiguous pages which are used
> to populate the mapping. I did not use any of the higher order
> allocators such as alloc_contig_range. Therefore, it is limited to

Just tried with a small prototype with an implementation similar to that
of alloc_gigantic_page() where we scan the zones (applicable zonelist)
for contiguous valid PFN range and try allocating with alloc_contig_range.
Will share it soon.

> allocations of MAX_ORDER size. Also, the allocations should probably

Just did a quick test and it worked till 1UL << (MAX_ORDER - 1) numbers
of pages on a POWER system with the current RFC patches. As the pages
are allocated during VMA creation time, comparison to normal page fault
speed while accessing the buffer wont be fair.

> be done outside mmap_sem but that was the easiest place to do it in
> this quick and easy POC.

Why it should be done outside the mmap_sem, because it can take some
time ? But then VMA can just go away while we are allocating the big
chunks of pages (if we dont hold mmap_sem).

 \ /
  Last update: 2017-10-12 12:37    [W:0.141 / U:12.100 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site