From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 7FB32273 for ; Wed, 14 Oct 2015 11:45:33 +0000 (UTC) Received: from resqmta-ch2-08v.sys.comcast.net (resqmta-ch2-08v.sys.comcast.net [69.252.207.40]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 35F1D16B for ; Wed, 14 Oct 2015 11:45:33 +0000 (UTC) Date: Wed, 14 Oct 2015 06:45:31 -0500 (CDT) From: Christoph Lameter To: Steven Rostedt In-Reply-To: <20151013124230.1a082d28@gandalf.local.home> Message-ID: References: <20151013124230.1a082d28@gandalf.local.home> Content-Type: text/plain; charset=US-ASCII Cc: ksummit-discuss@lists.linuxfoundation.org Subject: Re: [Ksummit-discuss] [TECH TOPIC] Mainlining PREEMPT_RT List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Tue, 13 Oct 2015, Steven Rostedt wrote: > preempt_disable and local_irq_disable annotations Hrm... Would there be a way to do Realtime without PREEMPT / PREEMPT_RT and such things? Doing this performance degradation is pretty significant and as far as I know makes this unacceptable for many uses. CONFIG_PREEMPT is already a problem. Or change CONFIG_PREEMPT first to be less intrusive? Have defined points where preemption can occur like CONFIG_PREEMPT_VOLUNTARY? Could we have realtime based on that? If we can keep the time between voluntary preemption short enough then this should do this as well. Plus we can likely reduce kernel complexity because code can rely on not being rescheduled unless an explicit call was done.