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[Qemu-devel] Re: [PATCH 0/3] piix_pci: optimize irq data path

From: Michael S. Tsirkin
Subject: [Qemu-devel] Re: [PATCH 0/3] piix_pci: optimize irq data path
Date: Thu, 17 Mar 2011 16:42:29 +0200
User-agent: Mutt/1.5.21 (2010-09-15)

On Thu, Mar 17, 2011 at 10:49:50PM +0900, Isaku Yamahata wrote:
> This patch series optimizes irq data path of piix_pci.
> So far piix3 tracks each pirq level and checks whether a given pic pins is
> asserted by seeing if each pirq is mapped into the pic pin.
> This is independent on irq routing, but data path is on slow path.
> Given that irq routing is rarely changed and asserting pic pins is on
> data path, the path that asserts pic pins should be optimized and
> chainging irq routing should be on slow path.
> The new behavior with this patch series is to use bitmap which is addressed
> by pirq and pic pins with a given irq routing.
> When pirq is asserted, the bitmap is set and see if the pic pins is
> asserted by checking the bitmaps.
> When irq routing is changed, rebuild the bitmap and re-assert pic pins.
> Isaku Yamahata (3):
>   pci: add accessor function to get irq levels
>   piix_pci: eliminate PIIX3State::pci_irq_levels
>   piix_pci: optimize set irq path
>  hw/pci.c      |    7 +++
>  hw/pci.h      |    1 +
>  hw/piix_pci.c |  126 
> ++++++++++++++++++++++++++++++++++++++++++++++++---------
>  3 files changed, 115 insertions(+), 19 deletions(-)

Thanks, I'll apply 1-2, 3 can be improved a bit but nothing major so
if you are busy I can apply as is and we can add fixups on top.
Let me know.


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