From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mario Smarduch Subject: Re: [RFT - PATCH v2 0/2] KVM/arm64: add fp/simd lazy switch support Date: Mon, 19 Oct 2015 15:06:59 -0700 Message-ID: <56256983.2030506@samsung.com> References: <1442964843-11953-1-git-send-email-m.smarduch@samsung.com> <20151005154540.GJ9011@cbox> <561BDFE3.5060403@samsung.com> <20151018210738.GF7531@cbox> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: marc.zyngier@arm.com, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org To: Christoffer Dall Return-path: In-reply-to: <20151018210738.GF7531@cbox> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu List-Id: kvm.vger.kernel.org On 10/18/2015 2:07 PM, Christoffer Dall wrote: > On Mon, Oct 12, 2015 at 09:29:23AM -0700, Mario Smarduch wrote: >> Hi Christoffer, Marc - >> I just threw this test your way without any explanation. > > I'm confused. Did you send me something somewhere already? Yes in the last patchset https://lists.cs.columbia.edu/pipermail/kvmarm/2015-October/016698.html I included a simple test I put together. > >> >> The test loops, does fp arithmetic and checks the truncated result. >> It could be a little more dynamic have an initial run to >> get the sum to compare against while looping, different fp >> hardware may come up with a different sum, but truncation is >> to 5'th decimal point. >> >> The rationale is that if there is any fp/simd corruption >> one of these runs should fail. I think most likely scenario >> for that is a world switch in midst of fp operation. I've >> instrumented (basically add some tracing to vcpu_put()) and >> validated vcpu_put gets called thousands of time (for v7,v8) >> for an over night test running two guests/host crunching >> fp operations. >> >> Other then that not sure how to really catch any problems >> with the patches applied. Obviously this is a huge issues, if this has >> any problems. If you or Marc have any other ideas I'd be happy >> to enhance the test. > > I think it's important to run two VMs at the same time, each with some > floating-point work, and then run some floating point on the host at the > same time. > > You can make that even more interesting by doing 32-bit guests at the > same time as well. Yes that's the test combination I've been running. > > I believe Marc was running Panranoia > (http://www.netlib.org/paranoia/paranoia.c) to test the last lazy > series. I'll try this test and run it for several days, see if anything shows up. Thanks. > > Thanks, > -Christoffer >