Comment by jcelerier
1 year ago
OTOH even lld, fast but fairly slower than mold, is already incredibly faster than MS's linker even without the incrmeentality. Like, I'm routinely linking hundreds of megabytes in less than a second anyways, not sure incrementality is that much worth it
Not a rhetorical question: Could it be that part of the speed difference is due to the file system speed? I was shocked when I saw how much modern(ish) Windows file systems were slower than modern(ish) Linux ones.
NTFS and ReFS are high performance file systems. But yes, it is due to file system filters, which OOTB means Windows Defender, though that can be extended by 3rd parties, including Sysinternals utils such as procmon.
Microsoft built a very extensible I/O stack and prior to Defender/prior to SSDs it really wasn't very noticable... back when it was originally designed well through the 90s and early 00s.
Unfortunately it is now noticable despite being an otherwise smart design. Which means Windows and/or NTFS are blamed as being slow, neither of which has any basis in fact when we look at the overall design of Windows' subsystems/VMM in comparison to macOS/Linux.
It sucks. You've got great plumbing in Windows with a shit shell on top.
Disabling Defender on directories involved in compiling and linking speeds up compile and link times by a factor of 5x or 6x. It's not a subtle difference.
I agonize over the insanity of removing Defender protection on precisely the files that are most vulnerable on my computer each time I do it. But I do it anyway.
Interestingly, Android Studio offers to turn off Defender protection for development directories for you, and does so each time you load a project, if you haven't already done so. So I no longer feel like I'm alone in my insanity.
it's usually windows defender and virus scanning that causes these massive slowdowns.
And as a result of this, if you want to optimize your program to be fast on Windows, you will make very different optimization decisions than on other platforms.
For example, Windows runs virus scans on close(), which makes it very slow. This means that sometimes it makes sense to have one or more background threads exclusively dedicated to closing files.
There's a good talk on this at https://www.youtube.com/watch?v=qbKGw8MQ0i8
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That’s exactly the problem “Dev Drive” is intended to solve I believe. I haven’t tried it myself.
https://learn.microsoft.com/en-us/windows/dev-drive/
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