[lkml]   [2019]   [Jul]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [Question] Should direct reclaim time be bounded?
On 7/4/19 4:09 AM, Michal Hocko wrote:
> On Wed 03-07-19 16:54:35, Mike Kravetz wrote:
>> On 7/3/19 2:43 AM, Mel Gorman wrote:
>>> Indeed. I'm getting knocked offline shortly so I didn't give this the
>>> time it deserves but it appears that part of this problem is
>>> hugetlb-specific when one node is full and can enter into this continual
>>> loop due to __GFP_RETRY_MAYFAIL requiring both nr_reclaimed and
>>> nr_scanned to be zero.
>> Yes, I am not aware of any other large order allocations consistently made
>> with __GFP_RETRY_MAYFAIL. But, I did not look too closely. Michal believes
>> that hugetlb pages allocations should use __GFP_RETRY_MAYFAIL.
> Yes. The argument is that this is controlable by an admin and failures
> should be prevented as much as possible. I didn't get to understand
> should_continue_reclaim part of the problem but I have a strong feeling
> that __GFP_RETRY_MAYFAIL handling at that layer is not correct. What
> happens if it is simply removed and we rely only on the retry mechanism
> from the page allocator instead? Does the success rate is reduced
> considerably?

It certainly will be reduced. I 'think' it will be hard to predict how
much it will be reduced as this will depend on the state of memory usage
and fragmentation at the time of the attempt.

I can try to measure this, but I will be a few days due to U.S. holiday.
Mike Kravetz

 \ /
  Last update: 2019-07-04 17:12    [W:0.042 / U:0.416 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site