In my testing, zram has much, much better compression than zswap.

The points about LRU inversion, cgroups, and so on are valid, but at the end of the day, I don’t really care. I was able to open as many firefox tabs as I wanted with zram, but I could not do so with zswap, and that’s what matters to me.

The author of a blogpost is a facebook engineer. Millions of ultra high performance Linux servers are a very different usecase than a single desktop. It’s perfectly reasonable for a solution for one to not be appropriate for the other.

Copied from my previous comment about this where ISO also gave a similar reply and was met with a similar response lmao.

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:

• Limited RAM space
• Swap will always/often happen (outside of (z)ram)
• Single tier of non-RAM swap
• Non-ram swap is significantly slower
• OOM can be preferable over (outside of ram) swapping
• Swapped out pages stay where they are until they are required by their process (important).

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Now let’s look at a possible modern workstation setup:

• Large RAM size
• Swap is rarely hit, especially if set up with zram.
• Multiple swap tiers beyond zram/zswap
  • Intel Optane disk used as a super-fast zram write-back device, or a high-priority swap
  • Fast NVME disk used as a second tier swap disk
  • Large HDD swap partition used as a third tier swap disk
• The biggest consideration is avoiding worst case latency, i.e. hitting HDD swap.
• Killing processes MUST be avoided, unless exceptional circumstances are hit where the kernel’s OOM would kick in anyway. This holds true even when HDD swap starts getting used.
• When unusual loads are observed, swapped pages can be moved around by the user (or a tool), by turning swap devices off and on. This is how you can empty the HDD swap partition for example.

This last point in particular should make it clear why his “imagination” was rather limited in his LRU inversion section.