From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:33434) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YflNY-0008M3-1m for qemu-devel@nongnu.org; Wed, 08 Apr 2015 04:30:33 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YflNW-0005k7-UH for qemu-devel@nongnu.org; Wed, 08 Apr 2015 04:30:32 -0400 Date: Wed, 08 Apr 2015 16:30:06 +0800 From: Jason Wang Message-Id: <1428481806.29276.4@smtp.corp.redhat.com> In-Reply-To: <11F8E995-8E2A-49CE-A493-D44510486CA8@suse.de> References: <1427876112-12615-1-git-send-email-jasowang@redhat.com> <1427876112-12615-17-git-send-email-jasowang@redhat.com> <55240BAE.8000705@suse.de> <5524E283.4060501@redhat.com> <11F8E995-8E2A-49CE-A493-D44510486CA8@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Subject: Re: [Qemu-devel] [PATCH V5 16/18] virtio-pci: increase the maximum number of virtqueues to 513 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alexander Graf Cc: "mst@redhat.com" , "qemu-devel@nongnu.org" , "qemu-ppc@nongnu.org" , "cornelia.huck@de.ibm.com" , Paolo Bonzini , Richard Henderson On Wed, Apr 8, 2015 at 4:13 PM, Alexander Graf wrote: > > > >> Am 08.04.2015 um 10:10 schrieb Jason Wang : >> >> >> >>> On 04/08/2015 12:54 AM, Alexander Graf wrote: >>>> On 04/01/2015 10:15 AM, Jason Wang wrote: >>>> This patch increases the maximum number of virtqueues for pci >>>> from 64 >>>> to 513. This will allow booting a virtio-net-pci device with 256 >>>> queue >>>> pairs. >>>> >>>> To keep migration compatibility, 64 was kept for legacy machine >>>> types. This is because qemu in fact allows guest to probe the >>>> limit of >>>> virtqueues through trying to set queue_sel. So for legacy machine >>>> type, we should make sure setting queue_sel to more than 63 won't >>>> make effect. >>>> >>>> Cc: Paolo Bonzini >>>> Cc: Richard Henderson >>>> Cc: Michael S. Tsirkin >>>> Cc: Alexander Graf >>>> Cc: qemu-ppc@nongnu.org >>>> Signed-off-by: Jason Wang >>>> --- >>>> hw/i386/pc_piix.c | 5 +++++ >>>> hw/i386/pc_q35.c | 5 +++++ >>>> hw/ppc/spapr.c | 5 +++++ >>>> hw/virtio/virtio-pci.c | 2 +- >>>> 4 files changed, 16 insertions(+), 1 deletion(-) >>>> >>>> diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c >>>> index 212e263..6e098ce 100644 >>>> --- a/hw/i386/pc_piix.c >>>> +++ b/hw/i386/pc_piix.c >>>> @@ -49,6 +49,7 @@ >>>> #include "hw/acpi/acpi.h" >>>> #include "cpu.h" >>>> #include "qemu/error-report.h" >>>> +#include "hw/virtio/virtio-bus.h" >>>> #ifdef CONFIG_XEN >>>> # include >>>> #endif >>>> @@ -312,6 +313,10 @@ static void pc_init_pci(MachineState >>>> *machine) >>>> static void pc_compat_2_3(MachineState *machine) >>>> { >>>> + ObjectClass *klass = object_class_by_name("virtio-pci-bus"); >>>> + VirtioBusClass *k = VIRTIO_BUS_CLASS(klass); >>>> + >>>> + k->queue_max = 64; >>>> } >>>> static void pc_compat_2_2(MachineState *machine) >>>> diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c >>>> index e67f2de..ff7c414 100644 >>>> --- a/hw/i386/pc_q35.c >>>> +++ b/hw/i386/pc_q35.c >>>> @@ -45,6 +45,7 @@ >>>> #include "hw/usb.h" >>>> #include "hw/cpu/icc_bus.h" >>>> #include "qemu/error-report.h" >>>> +#include "include/hw/virtio/virtio-bus.h" >>>> /* ICH9 AHCI has 6 ports */ >>>> #define MAX_SATA_PORTS 6 >>>> @@ -291,6 +292,10 @@ static void pc_q35_init(MachineState >>>> *machine) >>>> static void pc_compat_2_3(MachineState *machine) >>>> { >>>> + ObjectClass *klass = object_class_by_name("virtio-pci-bus"); >>>> + VirtioBusClass *k = VIRTIO_BUS_CLASS(klass); >>>> + >>>> + k->queue_max = 64; >>>> } >>>> static void pc_compat_2_2(MachineState *machine) >>>> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c >>>> index 8e43aa2..ee8f6a3 100644 >>>> --- a/hw/ppc/spapr.c >>>> +++ b/hw/ppc/spapr.c >>>> @@ -50,6 +50,7 @@ >>>> #include "hw/pci/pci.h" >>>> #include "hw/scsi/scsi.h" >>>> #include "hw/virtio/virtio-scsi.h" >>>> +#include "hw/virtio/virtio-bus.h" >>>> #include "exec/address-spaces.h" >>>> #include "hw/usb.h" >>>> @@ -1827,6 +1828,10 @@ static const TypeInfo spapr_machine_info = >>>> { >>>> static void spapr_compat_2_3(Object *obj) >>>> { >>>> + ObjectClass *klass = object_class_by_name("virtio-pci-bus"); >>>> + VirtioBusClass *k = VIRTIO_BUS_CLASS(klass); >>>> + >>>> + k->queue_max = 64; >>>> } >>>> static void spapr_compat_2_2(Object *obj) >>>> diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c >>>> index 9a5242a..02e3ce8 100644 >>>> --- a/hw/virtio/virtio-pci.c >>>> +++ b/hw/virtio/virtio-pci.c >>>> @@ -42,7 +42,7 @@ >>>> * configuration space */ >>>> #define VIRTIO_PCI_CONFIG_SIZE(dev) >>>> VIRTIO_PCI_CONFIG_OFF(msix_enabled(dev)) >>>> -#define VIRTIO_PCI_QUEUE_MAX 64 >>>> +#define VIRTIO_PCI_QUEUE_MAX 513 >>> >>> 513 is an interesting number. Any particular reason for it? Maybe >>> this >>> was mentioned before and I just missed it ;) >>> >>> >>> Alex >> >> The number were chose to match kernel limit for tuntap queues. >> Recent >> kernel allow up to 256 queues for tuntap, so 513 is in fact 256 * 2 >> plus >> 1 control vq. > > I see. I'm not fully convinced that it's a good idea to bake that > limit into qemu, but we have to have a limit somewhere. > > However, could you please make it more obvious in the code where thid > number stems from? Either by using defines or with a comment. > > > Alex Will add a comment for this. Thanks.