From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 6D2B2CE79C4 for ; Wed, 20 Sep 2023 10:38:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:In-Reply-To:References: Message-ID:Date:Subject:CC:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=fMEOtJG6/2Cv60iM32GzDFU4WCaFKjuB9vw1NwhFIAs=; b=OPoE1JWUwAej2M vLuYZRcKS4arGC0whWkSwNQG16SuXVh4PRCbCo0oQnUGulrPV0Q5PVY3zXa237LecFaF3oIy0R0Qk o1A7aDa7L3wdFBWdqm62LkD/CSkujbzyrhlGBhJEsA3iqapDbbhwfD6FeFALCo1kIfQkeNAI0CX74 JqgShkCtThTfyymQrwluOeakxp8jZS00fv9mQJQp72OqpxfXPLSFebp/QckrhIzHUTIBLYgL628rl NnqZ23DO1OwDZIX4/sT59JJ+inNEhnUCfHK6/QxXWVJrqYF27XkU35PGHfmr7cYqXVrvC4J3oMxKY eFh38/OeX78Cj7YdatXQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qiuam-002eDS-04; Wed, 20 Sep 2023 10:38:00 +0000 Received: from eu-smtp-delivery-151.mimecast.com ([185.58.85.151]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1qiuaj-002eBy-1p for linux-um@lists.infradead.org; Wed, 20 Sep 2023 10:37:59 +0000 Received: from AcuMS.aculab.com (156.67.243.121 [156.67.243.121]) by relay.mimecast.com with ESMTP with both STARTTLS and AUTH (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id uk-mta-284-5wXb8dyyPl6tQ9ufCu5NpA-1; Wed, 20 Sep 2023 11:37:47 +0100 X-MC-Unique: 5wXb8dyyPl6tQ9ufCu5NpA-1 Received: from AcuMS.Aculab.com (10.202.163.6) by AcuMS.aculab.com (10.202.163.6) with Microsoft SMTP Server (TLS) id 15.0.1497.48; Wed, 20 Sep 2023 11:37:43 +0100 Received: from AcuMS.Aculab.com ([::1]) by AcuMS.aculab.com ([::1]) with mapi id 15.00.1497.048; Wed, 20 Sep 2023 11:37:43 +0100 From: David Laight To: 'Linus Torvalds' , "John Paul Adrian Glaubitz" CC: Peter Zijlstra , Matthew Wilcox , Thomas Gleixner , Ankur Arora , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , "x86@kernel.org" , "akpm@linux-foundation.org" , "luto@kernel.org" , "bp@alien8.de" , "dave.hansen@linux.intel.com" , "hpa@zytor.com" , "mingo@redhat.com" , "juri.lelli@redhat.com" , "vincent.guittot@linaro.org" , "mgorman@suse.de" , "rostedt@goodmis.org" , "jon.grimm@amd.com" , "bharata@amd.com" , "raghavendra.kt@amd.com" , "boris.ostrovsky@oracle.com" , "konrad.wilk@oracle.com" , "jgross@suse.com" , "andrew.cooper3@citrix.com" , Geert Uytterhoeven , "linux-m68k@lists.linux-m68k.org" , Richard Weinberger , Anton Ivanov , Johannes Berg , "linux-um@lists.infradead.org" , Brian Cain , "linux-hexagon@vger.kernel.org" , "Richard Henderson" , Ivan Kokshaysky , Matt Turner , "linux-alpha@vger.kernel.org" Subject: RE: Arches that don't support PREEMPT Thread-Topic: Arches that don't support PREEMPT Thread-Index: AQHZ6x5UxOltR8DhjkKxVhgmNJa7b7AjhK8w Date: Wed, 20 Sep 2023 10:37:42 +0000 Message-ID: References: <87zg1u1h5t.fsf@oracle.com> <20230911150410.GC9098@noisy.programming.kicks-ass.net> <87h6o01w1a.fsf@oracle.com> <20230912082606.GB35261@noisy.programming.kicks-ass.net> <87cyyfxd4k.ffs@tglx> <87led2wdj0.ffs@tglx> <0e69f7df80dc5878071deb0d80938138d19de1d1.camel@physik.fu-berlin.de> <20230919134218.GA39281@noisy.programming.kicks-ass.net> In-Reply-To: Accept-Language: en-GB, en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230920_033757_876539_5F173EA1 X-CRM114-Status: GOOD ( 13.67 ) X-BeenThere: linux-um@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-um" Errors-To: linux-um-bounces+linux-um=archiver.kernel.org@lists.infradead.org From: Linus Torvalds > Sent: 19 September 2023 18:25 > > On Tue, 19 Sept 2023 at 06:48, John Paul Adrian Glaubitz > wrote: > > > > As Geert poined out, I'm not seeing anything particular problematic with the > > architectures lacking CONFIG_PREEMPT at the moment. This seems to be more > > something about organizing KConfig files. > > It can definitely be problematic. > > Not the Kconfig file part, and not the preempt count part itself. > > But the fact that it has never been used and tested means that there > might be tons of "this architecture code knows it's not preemptible, > because this architecture doesn't support preemption". Do distos even build x86 kernels with PREEMPT_FULL? I know I've had issues with massive latencies caused graphics driver forcing write-backs of all the framebuffer memory. (I think it is a failed attempt to fix a temporary display corruption.) OTOH SMP support and CONFIG_RT will test most of the code. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales) _______________________________________________ linux-um mailing list linux-um@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-um