From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Hansen Subject: Re: Slow Kernel Boot Date: Mon, 07 Jan 2008 14:46:59 -0800 Message-ID: <1199746019.9834.32.camel@localhost> References: <1199743548.9834.25.camel@localhost> <4782A4AF.6020902@qumranet.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel To: Izik Eidus Return-path: In-Reply-To: <4782A4AF.6020902-atKUWr5tajBWk0Htik3J/w@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Errors-To: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: kvm.vger.kernel.org On Tue, 2008-01-08 at 00:16 +0200, Izik Eidus wrote: > Dave Hansen wrote: > > With kvm-44, I thought my kernel was freezing during boot if I gave it > > 1G of RAM. But, it boots fine with 512M. > > > > So, I instrumented the kernel, and found out that it is just taking a > > long time to memset a 58MB area of memory for mem_map[]. It appears to > > be taking a mmio_exit for every access of every byte of memory. The end > > result is a ~100kbps memset() speed. Yes, 100 kilobytes/sec. > > > > I just tried kvm from git, and the kernel doesn't even get that far. I > > see this in debugfs > > > > insn_emulation:1393985 > > > > even before I get a single kernel message. And it keeps going up, fast. > > I can get the kernel to boot just fine if I give it less than 896MB of > > RAM. > > > > kvm-44 boots long enough for me to see a really funky e820 table: > > > > BIOS-provided physical RAM map: > > BIOS-e820: 0000000000000000 - 000000000009fc00 (usable) > > BIOS-e820: 000000000009fc00 - 00000000000a0000 (reserved) > > BIOS-e820: 00000000000e8000 - 0000000000100000 (reserved) > > BIOS-e820: 0000000000100000 - 00000000fffbd000 (usable) > > BIOS-e820: 00000000fffbd000 - 00000000ffff0000 (reserved) > > > > Note that this is with '-m 1G'!! It looks to me like one of those > > sections is basically from 0x100000 up to ~4G and *usable*. That > > doesn't look right. > > > yea it really dont look right, it look like it for some reason map the > whole memory up untill the bios to the kernel as memory > it even map it on the pci hole so... > hrmmm, very weird, > > what is your host info (32/64 amd/intel kernel...)? 64-bit intel host, kernel 2.6.24-rc5 Running kvm's current git userspace with modules from the same version. > and what is the > guest info (kernel 32/64...) ? 32-bit 2.6.23-rc6-mm1 > and what happen if you run it with -no-kvm ? Both current -git and kvm-44 seem to lock up at early kernel boot before even early printk is available. But, GRUB comes up in both cases. -no-kvm doesn't seem to change things at all. -- Dave ------------------------------------------------------------------------- Check out the new SourceForge.net Marketplace. It's the best place to buy or sell services for just about anything Open Source. http://ad.doubleclick.net/clk;164216239;13503038;w?http://sf.net/marketplace