2 ms·

> It's not a myth. As was posted elsewhere, they seem to be fast enough for games on the Nintendo Switch: https://news.ycombinator.com/item?id=17768537 https:/

> It's not a myth. As was posted elsewhere, they seem to be fast enough for games on the Nintendo Switch: https://news.ycombinator.com/item?id=17768537 https://news.ycombinator.com/item?id=17768537

monocasa 8y ago
I mean, on the switch, the filesystem is incredibly slow, and the GPU drivers use a ported version of Linux's Nvidia DRM drivers that runs most of the driver in the same process as the user code. So the only place where they've really optimized for performance between subsystems, they took a more exokernel like model.
- snaky 8y ago
  Quote from Linus, 2003 >><rant> >>Why do the file systems have to be so tightly integrated in the "ring0" core? This is one subsystem that screams for standard callouts and "ring1" level. >></rant off> > Because only naive people think you can do it efficiently any other way. > Face it, microkernels and message passing on that level died a long time ago, and that's a GOOD THING. > Most of the serious processing happens outside the filesystem (ie the VFS layer keeps track of name caches, stat caches, content caches etc), and all of those data structures are totally filesystem-independent (in a well-designed system) and are used heavily by things like memory management. Think mmap - the content caches are exposed to user space etc. But that's not the only thing - the name cache is used extensively to allow people to see where their data comes from (think "pwd", but on steroids), and none of this is anything that the low-level filesystem should ever care about. > At the same time, all those (ring0 - core) filesystem data structures HAVE TO BE MADE AVAILABLE to the low-level filesystem for any kind of efficient processing. If you think we're going to copy file contents around, you're just crazy. In other words, the filesystem has to be able to directly access the name cache, and the content caches. Which in turn means that it has to be ring0 (core) too. > If you don't care about performance, you can add call-outs and copy-in and copy-out etc crap. I'm telling you that you would be crazy to do it, but judging from some of the people in academic OS research, you wouldn't be alone in your own delusional world of crap. > Sorry to burst your bubble.

> It's not a myth. As was posted elsewhere, they seem to be fast enough for games on the Nintendo Switch: https://news.ycombinator.com/item?id=17768537 https://news.ycombinator.com/item?id=17768537

monocasa 8y ago

I mean, on the switch, the filesystem is incredibly slow, and the GPU drivers use a ported version of Linux's Nvidia DRM drivers that runs most of the driver in the same process as the user code. So the only place where they've really optimized for performance between subsystems, they took a more exokernel like model.

snaky 8y ago
Quote from Linus, 2003 >><rant> >>Why do the file systems have to be so tightly integrated in the "ring0" core? This is one subsystem that screams for standard callouts and "ring1" level. >></rant off> > Because only naive people think you can do it efficiently any other way. > Face it, microkernels and message passing on that level died a long time ago, and that's a GOOD THING. > Most of the serious processing happens outside the filesystem (ie the VFS layer keeps track of name caches, stat caches, content caches etc), and all of those data structures are totally filesystem-independent (in a well-designed system) and are used heavily by things like memory management. Think mmap - the content caches are exposed to user space etc. But that's not the only thing - the name cache is used extensively to allow people to see where their data comes from (think "pwd", but on steroids), and none of this is anything that the low-level filesystem should ever care about. > At the same time, all those (ring0 - core) filesystem data structures HAVE TO BE MADE AVAILABLE to the low-level filesystem for any kind of efficient processing. If you think we're going to copy file contents around, you're just crazy. In other words, the filesystem has to be able to directly access the name cache, and the content caches. Which in turn means that it has to be ring0 (core) too. > If you don't care about performance, you can add call-outs and copy-in and copy-out etc crap. I'm telling you that you would be crazy to do it, but judging from some of the people in academic OS research, you wouldn't be alone in your own delusional world of crap. > Sorry to burst your bubble.