Re: [Qemu-devel] Qemu and 32 PCIe devices

2017-08-09 Thread Michael S. Tsirkin
On Wed, Aug 09, 2017 at 09:26:11AM +0200, Paolo Bonzini wrote: > On 09/08/2017 03:06, Laszlo Ersek wrote: > >> 20.14% qemu-system-x86_64 [.] render_memory_region > >> 17.14% qemu-system-x86_64 [.] subpage_register > >> 10.31% qemu-system-x86_64

Re: [Qemu-devel] Qemu and 32 PCIe devices

2017-08-09 Thread Paolo Bonzini
On 09/08/2017 12:56, Laszlo Ersek wrote: > Allow me one last question -- why (and since when) does each device have > its own separate address space? Is that related to the virtual IOMMU? No (though it helps there too). It's because a device that has bus-master DMA disabled in the command registe

Re: [Qemu-devel] Qemu and 32 PCIe devices

2017-08-09 Thread Peter Maydell
On 9 August 2017 at 11:56, Laszlo Ersek wrote: > Now that I look at the "info mtree" monitor output of a random VM, I see > the following "address-space"s: > - memory > - I/O > - cpu-memory > - bunch of nameless ones, with top level regions called > "bus master container" > - several named "virt

Re: [Qemu-devel] Qemu and 32 PCIe devices

2017-08-09 Thread Laszlo Ersek
On 08/09/17 12:16, Paolo Bonzini wrote: > On 09/08/2017 12:00, Laszlo Ersek wrote: >> On 08/09/17 09:26, Paolo Bonzini wrote: >>> On 09/08/2017 03:06, Laszlo Ersek wrote: > 20.14% qemu-system-x86_64 [.] render_memory_region > 17.14% qemu-system-x86_64

Re: [Qemu-devel] Qemu and 32 PCIe devices

2017-08-09 Thread Paolo Bonzini
On 09/08/2017 12:00, Laszlo Ersek wrote: > On 08/09/17 09:26, Paolo Bonzini wrote: >> On 09/08/2017 03:06, Laszlo Ersek wrote: 20.14% qemu-system-x86_64 [.] render_memory_region 17.14% qemu-system-x86_64 [.] subpage_register 10.31% qemu-syst

Re: [Qemu-devel] Qemu and 32 PCIe devices

2017-08-09 Thread Laszlo Ersek
On 08/09/17 09:26, Paolo Bonzini wrote: > On 09/08/2017 03:06, Laszlo Ersek wrote: >>> 20.14% qemu-system-x86_64 [.] render_memory_region >>> 17.14% qemu-system-x86_64 [.] subpage_register >>> 10.31% qemu-system-x86_64 [.] int128_add >>>

Re: [Qemu-devel] Qemu and 32 PCIe devices

2017-08-09 Thread Paolo Bonzini
On 09/08/2017 03:06, Laszlo Ersek wrote: >> 20.14% qemu-system-x86_64 [.] render_memory_region >> 17.14% qemu-system-x86_64 [.] subpage_register >> 10.31% qemu-system-x86_64 [.] int128_add >>7.86% qemu-system-x86_64 [

Re: [Qemu-devel] Qemu and 32 PCIe devices

2017-08-08 Thread Laszlo Ersek
On 08/08/17 17:51, Laszlo Ersek wrote: > On 08/08/17 12:39, Marcin Juszkiewicz wrote: >> Anyway, beyond the things written in that comment, there is one very >> interesting symptom that makes me think another (milder?) bottleneck >> could be in QEMU: >> >> When having a large number of PCI(e) devi

Re: [Qemu-devel] Qemu and 32 PCIe devices

2017-08-08 Thread Laszlo Ersek
On 08/08/17 12:39, Marcin Juszkiewicz wrote: > > Few days ago I had an issue with getting PCIe hotplug working on > AArch64 machine. Enabled PCI hotplug in kernel and then got hit by > some issues. > > Out setup is a bunch of aarch64 servers and we use OpenStack to > provide access to arm64 systems

[Qemu-devel] Qemu and 32 PCIe devices

2017-08-08 Thread Marcin Juszkiewicz
Hello Few days ago I had an issue with getting PCIe hotplug working on AArch64 machine. Enabled PCI hotplug in kernel and then got hit by some issues. Out setup is a bunch of aarch64 servers and we use OpenStack to provide access to arm64 systems. OpenStack uses libvirt to control VMs and allows