I have been setting up Zram, Swap, Swappiness and EasyOOM daemon on 16gb ram boxes, or lower. Someone asked me about 32gb of ram, or more, and I’m unsure. Wondering if others have experimented with this!
I have been setting up Zram, Swap, Swappiness and EasyOOM daemon on 16gb ram boxes, or lower. Someone asked me about 32gb of ram, or more, and I’m unsure. Wondering if others have experimented with this!
Alright, I will only reply to you, since you raised a fair question.
First of all, I must admit that I thought what was linked was an earlier similar writing, but the general theme is still the same.
The problem with the writing is that it focuses on use-cases like Android and some servers, but doesn’t take into account other use-cases. It also seems to come with the assumption that setup is done by the distributor only, or if it’s done by the user, it’s a configure-and-forget situation.
What he represents is:
Now let’s look at a possible modern workstation setup:
This last point in particular should make it clear why his “imagination” was rather limited in his LRU inversion section.
This is not a good thing btw. Any unused anonymous page takes up space that could instead be used for file-backed pages that make your system faster.
Swap is not tiered storage!
Priorities control order of preference, not tiers. If you run out of space on a higher priority, it will not move that swap’s data to a lower priority swap. It will keep all of it exactly where it is and new data will hit the lower prio swap instead, no matter how hot it is.
Cool tech but it’s dead and was quite niche even when it was alive.
Not a thing you actually want to use for swap. It’s not an automatic writeback that is integrated into the Linux MM in any way. (Probably has some use-case for non-swap zram purposes though.)
This makes no sense at all unless you are extremely space-constrained on the NVMe and absolutely must not OOM – even if progress stalls to an absolute crawl.
This is neither feasible nor desirable. You don’t have enough granularity to do anything useful by doing so.
Even if you had, it’d work against the MM because it resurrects pages as “hot” that have been cold for a long time.
In any situation where swap is important, making the kernel think cold pages are hot is the very last thing you want.
I too wish it were but tiered/transcedental memory is not a thing in Linux and these hacks do not change that fact; they merely look similar if you don’t look close enough.
I cannot think of a single use-case where this would be preferable to a decently sized physical swap with zswap XOR just zram swap (if physical swap is infeasible).
Can you expand here. I think my attempt at brevity in this part wasn’t helpful.
I meant tiered with priorities only, yes.
We are not talking about the original purpose of Optane as supported on Windows. It’s just a (perhaps somewhat outdated) example of a storage device “smaller but faster than your average SSD storage”, which is very much not did tech.
Depends on the use-case. But yes, this can also be used as the fastest disk tier/priority of normal swap devices, which is why I mentioned both.
Why would you want to see killed processes when you go back to your workstation, in the 1/10000th scenario where something runs amok pushing memory usage to unexpected high levels? When you can simply investigate the reason behind the rare occurrence, then move all the pages off the slowest devices immediately with
swapoff?Intel optane? is there even any advantage left for optane compared with a fast, modern nvme disk?
It was just an example of a “smaller+faster than your average SSD”.
and I was mentioning something similar to my setup instead of an imaginary use-case.