From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christian Borntraeger Date: Fri, 04 Sep 2015 09:59:35 +0000 Subject: Re: KVM memory slots limit on powerpc Message-Id: <55E96B87.8020900@de.ibm.com> List-Id: References: <55E965FC.8080909@redhat.com> In-Reply-To: <55E965FC.8080909@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Thomas Huth , kvm-ppc@vger.kernel.org, qemu-ppc@nongnu.org, kvm@vger.kernel.org Cc: Alex Williamson , David Gibson , Bharata B Rao Am 04.09.2015 um 11:35 schrieb Thomas Huth: > > Hi all, > > now that we get memory hotplugging for the spapr machine on qemu-ppc, > too, it seems like we easily can hit the amount of KVM-internal memory > slots now ("#define KVM_USER_MEM_SLOTS 32" in > arch/powerpc/include/asm/kvm_host.h). For example, start > qemu-system-ppc64 with a couple of "-device secondary-vga" and "-m > 4G,slots2,maxmem@G" and then try to hot-plug all 32 DIMMs ... and > you'll see that it aborts way earlier already. > > The x86 code already increased the amount of KVM_USER_MEM_SLOTS to 509 > already (+3 internal slots = 512) ... maybe we should now increase the > amount of slots on powerpc, too? Since we don't use internal slots on > POWER, would 512 be a good value? Or would less be sufficient, too? When you are at it, the s390 value should also be increased I guess. Christian From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christian Borntraeger Subject: Re: KVM memory slots limit on powerpc Date: Fri, 04 Sep 2015 11:59:35 +0200 Message-ID: <55E96B87.8020900@de.ibm.com> References: <55E965FC.8080909@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Cc: Alex Williamson , David Gibson , Bharata B Rao To: Thomas Huth , kvm-ppc@vger.kernel.org, qemu-ppc@nongnu.org, kvm@vger.kernel.org Return-path: Received: from e06smtp16.uk.ibm.com ([195.75.94.112]:39986 "EHLO e06smtp16.uk.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752188AbbIDJ7n (ORCPT ); Fri, 4 Sep 2015 05:59:43 -0400 Received: from /spool/local by e06smtp16.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 4 Sep 2015 10:59:40 +0100 In-Reply-To: <55E965FC.8080909@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: Am 04.09.2015 um 11:35 schrieb Thomas Huth: > > Hi all, > > now that we get memory hotplugging for the spapr machine on qemu-ppc, > too, it seems like we easily can hit the amount of KVM-internal memory > slots now ("#define KVM_USER_MEM_SLOTS 32" in > arch/powerpc/include/asm/kvm_host.h). For example, start > qemu-system-ppc64 with a couple of "-device secondary-vga" and "-m > 4G,slots=32,maxmem=40G" and then try to hot-plug all 32 DIMMs ... and > you'll see that it aborts way earlier already. > > The x86 code already increased the amount of KVM_USER_MEM_SLOTS to 509 > already (+3 internal slots = 512) ... maybe we should now increase the > amount of slots on powerpc, too? Since we don't use internal slots on > POWER, would 512 be a good value? Or would less be sufficient, too? When you are at it, the s390 value should also be increased I guess. Christian