[Info-vax] RMS intro

[Dan Cross]

In article <58a152d7482131319b40481943ad2ff6ce71c166.camel at munted.eu>,
Single Stage to Orbit  <alex.buell at munted.eu> wrote:
>On Wed, 2024-01-03 at 13:29 +0000, Dan Cross wrote:
>> > > 
>> > > https://github.com/microsoft/WSL/issues/4197#issuecomment-604592340
>> > 
>> > Eh? I thought it was WSL1 that had the performance issuses, not
>> > WSL2.
>> 
>> Got a citation?  I'd believe it's the other way around; a world
>> switch into Linux from Windows is going to be more expensive
>> than a system call, and accessing a filesystem remotely (surely
>> how they implement access to NTFS from WSL2) will mean
>> ping-ponging between Windows and Linux several times to satisfy
>> an IO request.
>
>With WSL2, both the Windows NT kernel and the Linux kernel run on top
>of a hypervisor. It's a nice solution and performance differences
>between the two WSL systems should be night and day.
>
>https://thecodeblogger.com/2020/08/22/understanding-differences-between-wsl-1-and-wsl-2/

That doesn't really explain why you'd think that WSL1 would be
appreciably slower (or slower at all) than WSL2.  Consider that
Windows is still responsible for running IO devices and
providing access to e.g. the filesystem for Linux in the latter;
this will necessarily require lots of context switching between
the two (where in this context "context" means running in either
a Linux or Windows guest under a shared hypervisor) as Linux
accesses services provided by Windows.  In WSL1 there would be
no such overhead.

	- Dan C.