From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753539AbbAOTU0 (ORCPT ); Thu, 15 Jan 2015 14:20:26 -0500 Received: from mx1.redhat.com ([209.132.183.28]:50199 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752057AbbAOTUY (ORCPT ); Thu, 15 Jan 2015 14:20:24 -0500 Date: Thu, 15 Jan 2015 20:19:18 +0100 From: Oleg Nesterov To: Rik van Riel , Linus Torvalds , Suresh Siddha Cc: linux-kernel@vger.kernel.org, mingo@redhat.com, hpa@zytor.com, matt.fleming@intel.com, bp@suse.de, pbonzini@redhat.com, tglx@linutronix.de, luto@amacapital.net Subject: [PATCH 0/3] x86, fpu: kernel_fpu_begin/end initial cleanups/fix Message-ID: <20150115191918.GA27332@redhat.com> References: <1421012793-30106-1-git-send-email-riel@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1421012793-30106-1-git-send-email-riel@redhat.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add cc's. On 01/11, riel@redhat.com wrote: > > Currently the kernel will always load the FPU context, even > when switching to a kernel thread, or to an idle thread. In > the case of a task on a KVM VCPU going idle for a bit, and > waking up again later, this creates a vastly inefficient > chain of FPU context saves & loads: I assume you will send v2. Let me send initial kernel_fpu_begin/end cleanups, I believe they make sense anyway and won't conflict with your changes. This is actually resend, I sent more patches some time ago but they were ignored. Note that (I hope) we can do more changes on top of this series, in particular: - remove all checks from irq_fpu_usable() except in_kernel_fpu - do not abuse FPU in kernel threads, this makes sense even if use_eager_fpu(), and with or without the changes you proposed. Please review. Oleg.