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Re: Isolated Web Co Session crash Firefox-ESR



On 3 Dec 2023 14:33 +0800, from jeremy.ardley@gmail.com (jeremy ardley):
>> You have swap and it is enabled?
> 
> No Swap. I prefer not on SSD

Why not?

You are definitely putting the VM allocator in a much more difficult
spot than necessary by not providing any swap space.

If I read what you provided in a different message in this thread
correctly, over half of your RAM at that particular time was being
used for anonymous pages; that is, data which has no backing on other
storage, and therefore cannot be evicted from virtual memory. Combine
this with the fact that you have no swap, and all that data _must_ be
kept in RAM because that's all there is. Combine _that_ with running
several rather memory-hungry processes (several web browsers plus
LibreOffice) _and_ the Linux default of allowing memory
overcommitting, and I'm not all that surprised that you're apparently
hitting the OOM killer from time to time.

The reason for the system slowing down seems to me to likely be that
once the system comes under memory pressure (quite possibly due to an
increase in anonymous pages), it must evict something, and only
non-anonymous (that is, backed) pages can be evicted safely. So most
likely the allocator starts evicting program code, because that can be
read back from storage later, or other forms of cache, in order to
keep room for the anonymous pages which it cannot evict. The next time
that code is needed, it must go all the way to the (horribly slow by
comparison) storage, instead of originally just writing out to swap
some anonymous pages which haven't been used in comparatively forever,
like a tmpfs that someone mentioned, or data for inactive web browser
tabs or documents you aren't doing anything active with.

-- 
Michael Kjörling                     🔗 https://michael.kjorling.se
“Remember when, on the Internet, nobody cared that you were a dog?”


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