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SubjectRe: [PATCH 0/7] PV on HVM: receive interrupts as xen events
 On 08/30/2010 04:20 AM, Stefano Stabellini wrote:
> Hi all,
> this patch series introduces some performance improvements for xen PV on
> HVM guests: interacting with the emulated APIC is slow because it causes
> traps in the hypervisor while receiving xen events using the vector callback
> mechanism allow us to skip all that. For this reason we remap interrupts
> and MSIs into xen pirqs so that from that point on we can receive them
> as xen events instead.
> This series is based on Konrad's pcifront series (not upstream yet):
>
> http://lkml.org/lkml/2010/8/4/374
>
> and requires a patch to xen and a patch to qemu-xen (just sent to
> xen-devel).

My only concern with this series is the pirq remapping stuff. Why do
pirq and irq need to be non-identical? Is it because pirq is a global
namespace, and dom0 has already assigned it?

Why do guests need to know about max pirq? Would it be better to make
Xen use a more dynamic structure for pirqs so that any arbitrary value
can be used?

J

>
> The list of patches with diffstat follows:
>
> Jeremy Fitzhardinge (2):
> xen: add xen hvm acpi_register_gsi variant
> acpi: use indirect call to register gsi in different modes
>
> Stefano Stabellini (5):
> xen: xen: map MSIs into pirqs
> xen: support GSI -> pirq remapping in PV on HVM guests
> xen: implement xen_hvm_register_pirq
> xen: get the maximum number of pirqs from xen
> xen: support pirq != irq
>
>
> arch/x86/include/asm/acpi.h | 3 +
> arch/x86/include/asm/xen/pci.h | 10 +++
> arch/x86/kernel/acpi/boot.c | 60 ++++++++++++++------
> arch/x86/pci/xen.c | 114 ++++++++++++++++++++++++++++++++++++++
> drivers/pci/xen-pcifront.c | 2 +-
> drivers/xen/events.c | 106 +++++++++++++++++++++++++++++++----
> include/xen/events.h | 3 +
> include/xen/interface/features.h | 3 +
> include/xen/interface/physdev.h | 36 ++++++++++++
> 9 files changed, 308 insertions(+), 29 deletions(-)
>
>
> A git tree with this series and Konrad's pcifront series on top of Linux
> 2.6.36-rc1 is available here:
>
> git://xenbits.xen.org/people/sstabellini/linux-pvhvm.git 2.6.36-rc1-pvhvm-pirq-v3
>
> Cheers,
>
> Stefano Stabellini
>



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