From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ingo Molnar Subject: Re: [PATCH 1/2] RT: Preemptible Function-Call-IPI Support Date: Tue, 31 Jul 2007 11:19:03 +0200 Message-ID: <20070731091903.GA15822@elte.hu> References: <20070730211350.5162.99143.stgit@novell1.haskins.net> <20070730211539.5162.87483.stgit@novell1.haskins.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-rt-users@vger.kernel.org To: Gregory Haskins Return-path: Received: from mx3.mail.elte.hu ([157.181.1.138]:34045 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753892AbXGaJTS (ORCPT ); Tue, 31 Jul 2007 05:19:18 -0400 Content-Disposition: inline In-Reply-To: <20070730211539.5162.87483.stgit@novell1.haskins.net> Sender: linux-rt-users-owner@vger.kernel.org List-Id: linux-rt-users.vger.kernel.org * Gregory Haskins wrote: > This code allows FUNCTION_CALL IPIs to become preemptible by executing > them in kthread context instead of interrupt context. They are > referred to as "Virtual Function Call IPIs" (VFCIPI) because we no > longer rely on the actual FCIPI facility. Instead we schedule a > thread to run. This essentially replaces the synchronous FCIPI with > an async RESCHEDULE IPI. why do we need this? It's quite complex and brings little extra AFAICS. See the "schedule_on_each_cpu-enhance.patch" from Peter Ziljstra that lets a function to be executed on all CPUs. That should be extended (trivially) to execute a function on another CPU. That's all we need. Ingo