From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751176AbdGJEeM (ORCPT ); Mon, 10 Jul 2017 00:34:12 -0400 Received: from ozlabs.org ([103.22.144.67]:35389 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750785AbdGJEeL (ORCPT ); Mon, 10 Jul 2017 00:34:11 -0400 From: Michael Ellerman To: Nicholas Piggin , Gautham R Shenoy Cc: Michael Neuling , Vaidyanathan Srinivasan , Shilpasri G Bhat , "Rafael J. Wysocki" , Akshay Adiga , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org Subject: Re: [PATCH 4/5] powernv:idle: Move initialization of sibling pacas to pnv_alloc_idle_core_states In-Reply-To: <20170708190012.6c697975@roar.ozlabs.ibm.com> References: <1499272696-28751-1-git-send-email-ego@linux.vnet.ibm.com> <1499272696-28751-5-git-send-email-ego@linux.vnet.ibm.com> <20170707011609.76c51329@roar.ozlabs.ibm.com> <20170707150416.GD8913@in.ibm.com> <20170708190012.6c697975@roar.ozlabs.ibm.com> User-Agent: Notmuch/0.21 (https://notmuchmail.org) Date: Mon, 10 Jul 2017 14:34:08 +1000 Message-ID: <877ezgap1b.fsf@concordia.ellerman.id.au> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Nicholas Piggin writes: > On Fri, 7 Jul 2017 20:34:16 +0530 > Gautham R Shenoy wrote: >> On Fri, Jul 07, 2017 at 01:16:09AM +1000, Nicholas Piggin wrote: >> > >> > Speaking of which... core_idle_state and thread_sibling_pacas are >> > allocated with kmalloc_node... What happens if we take an SLB miss >> > in the idle wakeup code on these guys? Nothing good I think. Perhaps >> > we should put them into the pacas or somewhere in bolted memory. >> >> Yes, though the SLB miss hasn't yet been encountered in practise so >> far! > > Considering it's a node-affine allocation, it may actually be possible > to hit in practice on very large memory systems in practice. You can boot with disable_1tb_segments on the kernel command line to increase the change of hitting it. cheers