From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754985AbbKWQzf (ORCPT ); Mon, 23 Nov 2015 11:55:35 -0500 Received: from mailapp01.imgtec.com ([195.59.15.196]:49875 "EHLO mailapp01.imgtec.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754932AbbKWQzb (ORCPT ); Mon, 23 Nov 2015 11:55:31 -0500 Subject: Re: [PATCH 10/14] irqchip/mips-gic: Add a IPI hierarchy domaind To: Thomas Gleixner References: <1446549181-31788-1-git-send-email-qais.yousef@imgtec.com> <1446549181-31788-11-git-send-email-qais.yousef@imgtec.com> <56407F3C.4060404@imgtec.com> <564EFA74.90606@imgtec.com> CC: , , , , , From: Qais Yousef Message-ID: <565344FF.1090508@imgtec.com> Date: Mon, 23 Nov 2015 16:55:27 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [192.168.154.94] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/20/2015 08:39 PM, Thomas Gleixner wrote: >> Same applies when doing the reverse mapping. >> >> In other words, the ipi_mask won't always necessarily be linear to facilitate >> the 1:1 mapping that this approach assumes. >> >> It is a solvable problem, but I think we're losing the elegance that promoted >> going into this direction and I think sticking to using struct ipi_mapping >> (with some enhancements to how it's exposed an integrated by/into generic >> code) is a better approach. > The only reason to use the ipi_mapping thing is if we need non > consecutive masks, i.e. cpu 5 and 9. That's the case I had in mind. > > I really don't want to have it mandatory as it does not make any sense > for systems where the IPI is a single per_cpu interrupt. For the > linear consecutive space it is just adding memory and cache footprint > for no benefit. Think about machines with 4k and more cpus .... OK. Although so far I think the ovehead is higher without the ipi_mapping because of all the extra checkings we have to do when sending an IPI. I'll leave this to code review when I have something ready though. I'm debugging more problems and hopefully I'll send something this week. Thanks, Qais From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailapp01.imgtec.com ([195.59.15.196]:33789 "EHLO mailapp01.imgtec.com" rhost-flags-OK-OK-OK-OK) by eddie.linux-mips.org with ESMTP id S27013023AbbKWQzfNNi1T (ORCPT ); Mon, 23 Nov 2015 17:55:35 +0100 Subject: Re: [PATCH 10/14] irqchip/mips-gic: Add a IPI hierarchy domaind References: <1446549181-31788-1-git-send-email-qais.yousef@imgtec.com> <1446549181-31788-11-git-send-email-qais.yousef@imgtec.com> <56407F3C.4060404@imgtec.com> <564EFA74.90606@imgtec.com> From: Qais Yousef Message-ID: <565344FF.1090508@imgtec.com> Date: Mon, 23 Nov 2015 16:55:27 +0000 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit Return-Path: Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org List-help: List-unsubscribe: List-software: Ecartis version 1.0.0 List-subscribe: List-owner: List-post: List-archive: To: Thomas Gleixner Cc: linux-kernel@vger.kernel.org, jason@lakedaemon.net, marc.zyngier@arm.com, jiang.liu@linux.intel.com, ralf@linux-mips.org, linux-mips@linux-mips.org Message-ID: <20151123165527.pWCh3EVKC8cj7Mu0wJUQE21dvDLimeb6uB31cdX-T4M@z> On 11/20/2015 08:39 PM, Thomas Gleixner wrote: >> Same applies when doing the reverse mapping. >> >> In other words, the ipi_mask won't always necessarily be linear to facilitate >> the 1:1 mapping that this approach assumes. >> >> It is a solvable problem, but I think we're losing the elegance that promoted >> going into this direction and I think sticking to using struct ipi_mapping >> (with some enhancements to how it's exposed an integrated by/into generic >> code) is a better approach. > The only reason to use the ipi_mapping thing is if we need non > consecutive masks, i.e. cpu 5 and 9. That's the case I had in mind. > > I really don't want to have it mandatory as it does not make any sense > for systems where the IPI is a single per_cpu interrupt. For the > linear consecutive space it is just adding memory and cache footprint > for no benefit. Think about machines with 4k and more cpus .... OK. Although so far I think the ovehead is higher without the ipi_mapping because of all the extra checkings we have to do when sending an IPI. I'll leave this to code review when I have something ready though. I'm debugging more problems and hopefully I'll send something this week. Thanks, Qais