51–60 of 159 posts
Earlier quoted context omitted.
Instance store is also immediately wiped when the instance is halted / restarted, which can theoretically happen at any time, for example by a mystery instance failure, or a patching tool that's helpfully restarting your boxes during offhours.
My understanding is this not true, only when the instance permanently fails and is moved.
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Yeah, surprise Linux had to play catch up to a Windows 1994 release! Same with the scheduler, I'd argue Windows does OOM better than Linux today... Windows even had the concept of io_uring before, but network only with Registered I/O back in the Windows 8 (8.1?) days. Linux still lacks the "all I/O is async" NT has. The underlying kernel and executive of Windows aren't primitive pieces of trash. They're quite advance…
How difficult would it be to completely tear out the Windows desktop experience and just use the system and display drivers without the rest? Has anybody attempted such a feat?
On linux there also is preadv2(..., RWF_NOWAIT) which can be used to do optimistic non-blocking read from the page cache. That might be useful for io_method = worker to shave off a bit of latency. Try reading on the main thread with NOWAIT and only offload to a worker thread when that fails.
Note that we do not offload IO to workers when doing I/O that the caller will synchronously wait for, just when the caller actually can do IO asynchronously. That reduces the need to avoid the offload cost.
It turns out, as some of the results in Lukas' post show, that the offload to the worker is often actually beneficial particularly when the data is in the kernel page cache - it parallelizes the memory copy from kernel to userspace and postgres' checksum computation. Particularly on Intel server CPUs, which have had pretty mediocre per-core memory bandwidth in the last ~ decade, memory bandwidth turns out to be a bottleneck for page cache access and checksum computations.
Edit: Fix negation
On linux there also is preadv2(..., RWF_NOWAIT) which can be used to do optimistic non-blocking read from the page cache. That might be useful for io_method = worker to shave off a bit of latency. Try reading on the main thread with NOWAIT and only offload to a worker thread when that fails.
Aside from a few problems in specific Linux kernel versions, it works great.
Earlier quoted context omitted.
Yeah, surprise Linux had to play catch up to a Windows 1994 release! Same with the scheduler, I'd argue Windows does OOM better than Linux today... Windows even had the concept of io_uring before, but network only with Registered I/O back in the Windows 8 (8.1?) days. Linux still lacks the "all I/O is async" NT has. The underlying kernel and executive of Windows aren't primitive pieces of trash. They're quite advance…
How difficult would it be to completely tear out the Windows desktop experience and just use the system and display drivers without the rest? Has anybody attempted such a feat?
Win32 is also responsible for core Services, which means you can't de-Windows-ify Windows and strip it down to an NT API-only. All other personalities (OS/2, POSIX, SFU) have a dependency on Win32, as well.
You're still running the WindowServer of course; it's part of the Executive.
That said, with a bunch of modifications, NTDEV did get Windows 11 down to it's bare minimum, and text only to boot. So I guess it's technically possible, though not useful.
Earlier quoted context omitted.
Yeah, surprise Linux had to play catch up to a Windows 1994 release! Same with the scheduler, I'd argue Windows does OOM better than Linux today... Windows even had the concept of io_uring before, but network only with Registered I/O back in the Windows 8 (8.1?) days. Linux still lacks the "all I/O is async" NT has. The underlying kernel and executive of Windows aren't primitive pieces of trash. They're quite advance…
How difficult would it be to completely tear out the Windows desktop experience and just use the system and display drivers without the rest? Has anybody attempted such a feat?
Earlier quoted context omitted.
How difficult would it be to completely tear out the Windows desktop experience and just use the system and display drivers without the rest? Has anybody attempted such a feat?
There is Windows Server Core which removes everything but a CLI, but you still have the normal login experience, you still have a "desktop" (no start menu, taskbar, etc), you can still launch normal Win32 apps... for the most part (task manager, notepad, and so on). Win32 is also responsible for core Services, which means you can't de-Windows-ify Windows and strip it down to an NT API-only. All other personalities (O…
Yep, they've replaced nearly every UI with text (the login window is a TUI), though there's still some shell DLLs and the whole thing still uses a window manager. That's honestly for the best, since it allows you to migrate full installations with some UI-based apps to a Core installation with them intact.
> That said, with a bunch of modifications, NTDEV did get Windows 11 down to it's bare minimum, and text only to boot. So I guess it's technically possible, though not useful.
Windows has had a "text mode" since at least Windows XP IIRC, but it's really not that useful, if at all. Even for rescue operations you're better off with Windows PE.
On linux there also is preadv2(..., RWF_NOWAIT) which can be used to do optimistic non-blocking read from the page cache. That might be useful for io_method = worker to shave off a bit of latency. Try reading on the main thread with NOWAIT and only offload to a worker thread when that fails.
FWIW, I played with that - unfortunately it seems that the the overhead of doing twice the page cache lookups is a cure worse than the disease. Note that we do not offload IO to workers when doing I/O that the caller will synchronously wait for, just when the caller actually can do IO asynchronously. That reduces the need to avoid the offload cost. It turns out, as some of the results in Lukas' post show, that the of…
Earlier quoted context omitted.
Sounds like this feature is based on io_uring which is a Linux feature. I would be surprised if they implemented async io on Windows before they would on Linux given the user/deployment base being very Linux-heavy.
Yeah, surprise Linux had to play catch up to a Windows 1994 release! Same with the scheduler, I'd argue Windows does OOM better than Linux today... Windows even had the concept of io_uring before, but network only with Registered I/O back in the Windows 8 (8.1?) days. Linux still lacks the "all I/O is async" NT has. The underlying kernel and executive of Windows aren't primitive pieces of trash. They're quite advance…
Windows does OOM far better than Linux because it doesn't really overcommit RAM.
But the CPU _scheduler_ in Linux is far, far, far better than in Windows. Linux can even do hard-realtime, after all.