I could see implementing it for testing if you wanted to maybe look at latency through the block storage stack, which would be called (I think) if an slog is present and one needed a sync write (vs. say sync=disabled). (Although I think for all practical purposes the code stack latency would be negligible.) Or if you wanted to understand the additional system HW latency you were incurring with some sort of block slog device. Then again given the code stack latency is nil vs. us or ms latency on devices, sync=disabled would be just as good a compare for measuring HW latency. (I think.)
Exactly. If you want to compare the block storage stack your solution is to use sync=disabled versus sync=enabled with whatever hardware you want to test. You are right that if your code stack latency is even measurable your performance is so incredibly poor that you aren't looking for an slog device to help, you're looking for a way to stop the bleeding on your wrists because you have no clue what is broken and were hoping a sacrifice would fix the server. ;)
There is literally no test I can conceive of where you'd want to measure something and compare sync=disabled versus sync=enabled with a memory device, aside from seeing big numbers and getting a woody over it. There are people out there that just love seeing big numbers (two of my close friends live for that stuff). I'm more pragmatic than I was a decade ago as the numbers matter to me when I'm trying to find the upper limits for real-world applications. But there is no use, in any real-world scenario, where you'd want to do sync=enabled and then use memory device. You are just flat out better off doing sync=disabled at that point (and I have done that on occasion for testing purposes).
Yeah, 'retarded' is my personal opinion. I won't repeat what others say because some people say things even less friendly than what I said.
I never speak for iXsystems when here as that is not in my job description. I just peruse the forums to:
1. Make sure things are being prioritized properly. If 200 people have a particular problem I make sure that the higher ups know not to wait 3 months to fix it.
2. Help out if I can since I'm pretty knowledgeable in this stuff. I do have my limits though, but if I feel it is important (or I just want to know) I just ask a developer since they're a phone call away for me.
3. Flame people named toadman and jgreco because I get $1 for each flame post. ;)