Date: Thu, 24 Oct 2024 02:05:34 +0300 From: Vadim Goncharov <vadimnuclight@gmail.com> To: gnn <gnn@freebsd.org> Cc: Arch <freebsd-arch@freebsd.org> Subject: Re: Building kernels with FPU support? Message-ID: <20241024020534.37003492@nuclight.lan> In-Reply-To: <E37A7972-7FBE-4428-81E1-8DC6D0F67726@freebsd.org> References: <E37A7972-7FBE-4428-81E1-8DC6D0F67726@freebsd.org>
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On Wed, 23 Oct 2024 10:38:12 -0400 gnn <gnn@freebsd.org> 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. -- WBR, @nuclight
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