From nobody Wed Oct 23 14:38:12 2024 X-Original-To: freebsd-arch@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4XYWqw05Tbz5ZJqD for ; Wed, 23 Oct 2024 14:38:20 +0000 (UTC) (envelope-from gnn@freebsd.org) Received: from smtp.freebsd.org (smtp.freebsd.org [IPv6:2610:1c1:1:606c::24b:4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "smtp.freebsd.org", Issuer "R10" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4XYWqv6lcXz4ng6 for ; Wed, 23 Oct 2024 14:38:19 +0000 (UTC) (envelope-from gnn@freebsd.org) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1729694299; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=bfyvM7hdao88PfGm0XSPdPNex2hWIfJbMvDuMdEED6s=; b=TB9WuIARRz+SRPMlPeE/8wLAqOMk/wKzCUrguMqiV1pTbmbJmqOtEmULArKa3WlfWWZNhZ SI73gHW72EB/oRQrN3rcsuvZ2sABrqF7ztPxPtv7WKGBxA/UKKEENniOfkxmrN3u9JOd6l h/D7J5SRq2gnWEhGDhIMYZ7rTtuSssQauqrKXj9IXplqHOW4LnOm/NWHxL7NcAckYGYd2g rFxDg0n/3D1dXxP8Xw0RKXi4sfkIF6ZqBVctoFi+R1+4idicxRRTaf5+jFjZubHr8182p6 Ln7OC+9Xlny2/zEUcVL2bBl1li1/dGEVm//Wv0ECfgT0eNsnPHzlTxsPEwWvpg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1729694299; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=bfyvM7hdao88PfGm0XSPdPNex2hWIfJbMvDuMdEED6s=; b=i8Tn3gP0Czt3UK5lAZynFLcK41MVwk20K2d58ICY58Zggw8ZL44uJL5L4JayY5S9m3dPPo pz//wPwZiEov/5wlPXAnjcsphYLgepzUuhe73NzOUZ/zRuILLT0bXuLHF+HQ5JuzR8vKYm WChFYTs63798iUnnbefmkdj+yldcyslsBCvKMVpx+FZ4RKz0039UIRx7ELm3U/GLP+YkaK +dnHvsz+orIUQe/cR0jKurODoeqEiaJ7heGlQq86I1TbY9n7U6xuRzNnzVH6IVP/LiS27m jqHfJpqTErzkI34gStcr9xNKTUnK8rRDdsSniqf7o5qDhNYPRqsol7Mvuj4BXw== ARC-Authentication-Results: i=1; mx1.freebsd.org; none ARC-Seal: i=1; s=dkim; d=freebsd.org; t=1729694299; a=rsa-sha256; cv=none; b=Wrni3HhcUQCcEV3O8WzZXM37vo+6mc6tFQjMuyf95MEIvLyQ8CM8NauDpzUDfQSgFTIsa+ Ueet2Qg+H54vkiJteTnI7ectUkYfcBlbKmyzBLWIom223H+svsqau94dmTCxG1SgkoSif8 nESG13MVbZOGNuZbHQMN+Vb7W0FJhR1FbiZ895xhS+r0hsbZMUszgpKfIy5526zypJtkAl s8Kg38pl9ULfO8ZGzkdMPYxMW40qeH/p/IvsPq3O96g3vipZ7qtS7bO6hwwfh9RLZMjNZm 2Lf/GJ2ViUeNstW2WZ4I7UperUHBWb/gFalB/uk7KF/rcbd87zVzpQt+vMhTxw== Received: from [192.168.68.1] (unknown [69.94.58.76]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) (Authenticated sender: gnn) by smtp.freebsd.org (Postfix) with ESMTPSA id 4XYWqv5QDNz11Rk for ; Wed, 23 Oct 2024 14:38:19 +0000 (UTC) (envelope-from gnn@freebsd.org) From: gnn To: Arch Subject: Building kernels with FPU support? Date: Wed, 23 Oct 2024 10:38:12 -0400 X-Mailer: MailMate (1.14r5937) Message-ID: List-Id: Discussion related to FreeBSD architecture List-Archive: https://lists.freebsd.org/archives/freebsd-arch List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-arch@FreeBSD.org MIME-Version: 1.0 Content-Type: text/plain; markup=markdown Content-Transfer-Encoding: quoted-printable Howdy, I am wondering if anyone has tried, lately, to see what effect building w= ith FPU support has on overall system performance. I've been working wit= h 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 not= e 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 g= eneral question of "does it matter?" and "if so, how much?" Best, George