Re: is hibernation usable?

On Thu, Feb 20, 2020 at 12:45 PM Luigi Semenzato [off-list ref] wrote:

On Thu, Feb 20, 2020 at 11:09 AM Chris Murphy [off-list ref] wrote:

quoted

On Thu, Feb 20, 2020 at 10:16 AM Luigi Semenzato [off-list ref] wrote:

quoted

I think this is the right group for the memory issues.

I suspect that the problem with failed allocations (ENOMEM) boils down
to the unreliability of the page allocator.  In my experience, under
pressure (i.e. pages must be swapped out to be reclaimed) allocations
can fail even when in theory they should succeed.  (I wish I were
wrong and that someone would convincingly correct me.)

What is vm.swappiness set to on your system? A fellow Fedora
contributor who has consistently reproduced what you describe, has
discovered he has vm.swappiness=0, and even if it's set to 1, the
problem no longer happens. And this is not a documented consequence of
using a value of 0.

I am using the default value of 60.

A zero value should cause all file pages to be discarded before any
anonymous pages are swapped.  I wonder if the fellow Fedora
contributor's workload has a lot of file pages, so that discarding
them is enough for the image allocator to succeed. In that case "sync;
echo 1 > /proc/sys/vm/drop_caches" would be a better way of achieving
the same result.  (By the way, in my experiments I do that just before
hibernating.)

He reports hibernation failure even if he drops caches beforehand.

https://lists.fedoraproject.org/archives/list/desktop@lists.fedoraproject.org/message/XYWYF33RFVISVZTPYSJRRXP7TFXPV4GD/

-- 
Chris Murphy