From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3swCkK6Xv0zDt6t for ; Fri, 14 Oct 2016 14:28:57 +1100 (AEDT) Received: from pps.filterd (m0098414.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.17/8.16.0.17) with SMTP id u9E3OZm6092743 for ; Thu, 13 Oct 2016 23:28:55 -0400 Received: from e23smtp09.au.ibm.com (e23smtp09.au.ibm.com [202.81.31.142]) by mx0b-001b2d01.pphosted.com with ESMTP id 262max5wjp-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Thu, 13 Oct 2016 23:28:55 -0400 Received: from localhost by e23smtp09.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 14 Oct 2016 13:28:52 +1000 Received: from d23relay09.au.ibm.com (d23relay09.au.ibm.com [9.185.63.181]) by d23dlp02.au.ibm.com (Postfix) with ESMTP id 8BDDE2BB005A for ; Fri, 14 Oct 2016 14:28:49 +1100 (EST) Received: from d23av01.au.ibm.com (d23av01.au.ibm.com [9.190.234.96]) by d23relay09.au.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id u9E3SnSO37617840 for ; Fri, 14 Oct 2016 14:28:49 +1100 Received: from d23av01.au.ibm.com (localhost [127.0.0.1]) by d23av01.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id u9E3Smhh030535 for ; Fri, 14 Oct 2016 14:28:49 +1100 Date: Fri, 14 Oct 2016 14:28:47 +1100 From: Sam Bobroff To: Suraj Jitindar Singh Cc: pbonzini@redhat.com, rkrcmar@redhat.com, agraf@suse.com, corbet@lwn.net, paulus@samba.org, mpe@ellerman.id.au, kvm@vger.kernel.org, kvm-ppc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, benh@kernel.crashing.org, linux-doc@vger.kernel.org Subject: Re: [PATCH 0/6] kvm: powerpc halt polling updates References: <1476406404-32752-1-git-send-email-sjitindarsingh@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1476406404-32752-1-git-send-email-sjitindarsingh@gmail.com> Message-Id: <20161014032847.GA27267@tungsten.ozlabs.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Fri, Oct 14, 2016 at 11:53:18AM +1100, Suraj Jitindar Singh wrote: > This patch series makes some updates and bug fixes to the powerpc kvm-hv > halt polling code. > > The first two patches are concerned with exporting the generic kvm module > parameter variables and accessing these from the powerpc specific code. > > The third patch fixes a bug where changing the global max halt polling > interval module parameter can sometimes have no effect. > > The fourth patch decreases the default global max halt polling interval > to something more sensible. > > The fifth patch contains generic fixups with no functional effect. > > The last patch adds halt polling documentation. > > Suraj Jitindar Singh (6): > kvm: export kvm module parameter variables > powerpc/kvm: Use generic kvm module parameters in kvm-hv > powerpc/kvm: Add check for module parameter halt_poll_ns > powerpc/kvm: Decrease the powerpc default halt poll max value > powerpc/kvm: Comment style and print format fixups > doc/kvm: Add halt polling documentation > > Documentation/virtual/kvm/00-INDEX | 2 + > Documentation/virtual/kvm/halt-polling.txt | 127 +++++++++++++++++++++++++++++ > arch/powerpc/include/asm/kvm_host.h | 2 +- > arch/powerpc/kvm/book3s_hv.c | 33 ++------ > arch/powerpc/kvm/trace_hv.h | 2 +- > include/linux/kvm_host.h | 4 + > virt/kvm/kvm_main.c | 9 +- > 7 files changed, 149 insertions(+), 30 deletions(-) > create mode 100644 Documentation/virtual/kvm/halt-polling.txt > > -- > 2.5.5 Hi Suraj, I've given this set a quick test and it seems to work fine. I used a repetitive wakeup, using a nanosleep loop in guest userspace (with real time prio), and I was able to cause halt polling to switch on and off as I adjusted halt_poll_ns. I think the new default value is much better: halt polling started (e.g. CPU utilization rose to 100%) once CPU utilization had already risen to about 75%. Cheers, Sam. Tested-by: Sam Bobroff