From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751708AbdGUELT (ORCPT ); Fri, 21 Jul 2017 00:11:19 -0400 Received: from aserp1040.oracle.com ([141.146.126.69]:27026 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750801AbdGUELR (ORCPT ); Fri, 21 Jul 2017 00:11:17 -0400 Subject: Re: [PATCH 0/2] sparc64: Use low latency path to resume idle cpu To: David Miller Cc: sparclinux@vger.kernel.org, rob.gardner@oracle.com, anthony.yznaga@oracle.com, linux-kernel@vger.kernel.org References: <20170721.035526.1236051430538663900.davem@davemloft.net> <3bb6d4bb-ebf1-1a1f-9766-b02a187cbe1e@oracle.com> <20170721.044510.1044996118554999021.davem@davemloft.net> From: Vijay Kumar Organization: Oracle Corporation Message-ID: Date: Thu, 20 Jul 2017 23:11:45 -0500 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 MIME-Version: 1.0 In-Reply-To: <20170721.044510.1044996118554999021.davem@davemloft.net> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-Source-IP: userv0021.oracle.com [156.151.31.71] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/20/2017 10:45 PM, David Miller wrote: > From: Vijay Kumar > Date: Thu, 20 Jul 2017 22:36:42 -0500 > >> I can give a try :). But looks to me one thing that will go wrong is >> irq accounting done in __irq_enter() and rcu_irq_enter(). > Actually, the bigger problem is that scheduler_ipi() can raise a > software interrupt, and nothing will invoke it. Yes, I see your point. > It's turning quite ugly to avoid the IRQ overhead, I must admit. > So ignore this for now. > > In the longer term a probably cleaner way to do this is to have > a special direct version of scheduler_ipi() that invokes all the > necessary work, even the rebalance softirq, directly rather than > indirectly. Sure. Thanks.