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Windows Server 2025 Runs Better on ARM

jasoneckert.github.io

91–100 of 156 posts

Re: Windows Server 2025 Runs Better on ARM

#91

>Across multiple runs of each test, the Snapdragon system produced consistent, repeatable timings nearly every time. On the Intel system, results varied significantly, occasionally beating the Snapdragon, but most of the time falling behind. The Snapdragon was the clear winner on each test overall. They blogged everything to generate the setup, including the hunch and test code but the anecdotal results are missing.…

I intentionally left out screenshots of the output for a couple of reasons: 1) They’d distract from the main point (I wasn’t aiming to write a benchmarking post), and 2) They can be misleading, since results will vary across ARM hardware and even between Snapdragon X Elite variants. Instead, I included the PowerShell snippets so anyone interested can reproduce the results themselves. For a rough sense of the outcome:…

> so anyone interested can reproduce the results themselves.

Weird reasoning.

You already caught our attention with your article. But not everyone has the time or means to go and re-do the tests.

However such information is really important to surface when making infra decisions. And if one of the brain cells pops up and says something about 20-80% perf improvement VS there were some perf improvements - which would be more convincing to research the topic when the time comes for the reader to benefit from your research?

Re: Windows Server 2025 Runs Better on ARM

#94

Earlier quoted context omitted.

Both Windows 11 systems are configured with the “High performance” power plan, as are the two Windows Server VMs. In hindsight, I should have included this detail explicitly in the original post instead of only alluding to it.

Even if you do that, there are firmware-level overrides that most laptops won't allow you to override. If you did, the laptop would melt. You might be benchmarking the chassis fans more than the CPUs!

Agreed. Not to mention NVME SSD throttle pretty quickly due to heat too.

Re: Windows Server 2025 Runs Better on ARM

#95
post #6
post #4

Earlier quoted context omitted.

in no way that I can see is MSSQL or Server "legacy".

The only people using MSSQL Server are people deep, deep in the Microsoft ecosystem. Think government work, and those unlucky enough to work at a pure Microsoft shop where every problem looks like a Microsoft or Azure solution. It's not a dominant database anywhere on the outside.

I've worked for plenty of companies using MsSql.

They have all been dotnet ecosystem, but self hosted rather than Azure

I think the latest versions of SQL Server also run on Linux now.

Re: Windows Server 2025 Runs Better on ARM

#96
post #85

Earlier quoted context omitted.

> You can turn it on globally for all processes by creating a DWORD value named "Enabled" under HKLM\SYSTEM\CurrentControlSet\Control\Session Manager\Segment Heap, and giving it a value of 3 I had previously seen this described as 0 vs non-zero. Since you have some inside experience :), anything special about 3 instead? What about 2? How would I find these value meanings out on my own (if that's even possible)? Thank…

It's a combinination of bit flags. The lowest bit controls whether segment heap is on or off. The 2nd lowest bit bit controls some additional optimizations that go along with it, something about multithreading. A value of 3 (both flags set) gives you identical behavior to what specifying SegmentHeap in your application manifest does. Using the application manifest approach is the right way to ship software that opts…

How often does software actually ship with the opt in for segment heap turned on though ?

Anyway to globally turn it on when a blacklist or denylist or whatever in case something individual acts up ?

Re: Windows Server 2025 Runs Better on ARM

#97
post #37

Windows developer here. After reading this post, my gut instinct is that this is due to something called 'segment heap'. A bit of backstory: there are two, totally independent implementations behind the Windows heap allocation APIs (i.e. the implementation code behind RtlHeapAlloc and RtlHeapFree, which are called by malloc/free). The older of the two, developed uring the Dave Cutler era, is known as the "NT heap". T…

Seems like a no brainer on virtualised environments for Windows servers ?

Also assuming that most Microsoft first party applications in Windows server (DNS, etc etc) would all be optimised for segment heap ?

Re: Windows Server 2025 Runs Better on ARM

#98
post #2

Typical approach on an HV server is to disable C States, set power management to high, etc preventing x86 from downclocking. Keeping the CPU from seesawing can have big improvements. But you’re not going to do that in a lab/personal machine, usually.

Or just disable turbo boost

Re: Windows Server 2025 Runs Better on ARM

#99
post #17

Earlier quoted context omitted.

Building Unreal games. Running windows containers. Windows server is actually kind of awesome for when you need a Windows machine. Linux is great for servers but Windows server is the real Windows pro. Rock solid and none of the crap. The worst part of Windows server is knowing that Microsoft can make a good operating system and chooses not to.

Yes I only recently understood why people use Windows Server as a desktop operating system - it looks and feels like old Windows.

LTSC is even better !

Re: Windows Server 2025 Runs Better on ARM

#100
post #52

What is the RAM and storage on each of these machines? Is it possible the Snapdragon has packaged RAM (with faster interconnects as a result), and the x86 machine is using DIMMs with longer traces? And what about storage? For that matter, what CPUs are you using? Its possible ARM is a better architecture. But a lot of benchmarks end up stressing one part of the system more than any other. And if thats the case, faste…

Both systems have DDR5 soldered to the mainboard and NVMe SSDs (the Intel system has a faster Samsung model compared to the Foresee model in the Snapdragon system).

Would be good test those SSD to see when they thermally throttle. Most hit pretty fast (on desktop drives it's quite easy to add heat sinks and they make a big difference)
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