Re: Building kernels with FPU support?
gnn <[email protected]>
| Newsgroups | gmane.os.freebsd.architechture |
|---|---|
| Message-ID | <[email protected]> |
On 23 Oct 2024, at 19:05, Vadim Goncharov wrote: > On Wed, 23 Oct 2024 10:38:12 -0400 > gnn <[email protected]> wrote: > >> Howdy, >> >> I am wondering if anyone has tried, lately, to see what effect >> building with FPU support has on overall system performance. I've >> been working with a kernel module that needs this (for reasons I'll >> not go into now) and it occurred to me that the perceived performance >> overhead that caused us to only do fixed point in the kernel may no >> longer be significant. I note that Linux has an option to build >> their kernel with FPU support. >> >> And yes, I know that we have the ability to selectively deal with the >> FPU, from the calls outlined in Section 9 for fpu, but I'm asking the >> more general question of "does it matter?" and "if so, how much?" > > Would be great to have it for e.g. having portions of SQLite in kernel, > e.g. it's R*Tree module for fast 5-dimensions lookup (like for firewall > rules) uses floats. Funny you should mention sqlite in the kernel, since that's the exact use case that started me down this path, and is covered in a paper I've co-authored that's been accepted for publication at a database conference in 2025. I am sure there are other use cases, we already have this on for the openssl module, for example. Best, George