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[Qemu-devel] Re: [PATCH v7 0/4] piix_pci: optimize irq data path
From: |
Michael S. Tsirkin |
Subject: |
[Qemu-devel] Re: [PATCH v7 0/4] piix_pci: optimize irq data path |
Date: |
Fri, 1 Apr 2011 17:38:57 +0300 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Fri, Apr 01, 2011 at 08:43:20PM +0900, Isaku Yamahata wrote:
> Here is v7 which are rebased to pci branch.
>
> I tested this patch series as follows. please see the commit message
> for details.
> - 3/4 piix_pci: optimize set irq path
> Run linux as guest with 4 e1000 emulated devices.
> And confirmed that each PIRQ[A-D] are able to assert interrupts.
> - 4/4 piix_pci: load path clean up
> Run linux as guest with one e1000 emulated device.
> savevm/loadvm guest with runing ping -f in guest.
>
> To be honest, the patch, "4/4 piix_pci: load path clean up", needs more
> extensive tests. For example live migration and stress test.
> But for now I don't have plan to further testing in near future. Sorry.
> So please feel free to pick or drop the last patch.
Applied, I will hit it with autotest.
> patch description:
> 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.
>
> Changes v6 -> v7:
> - rebased to pci branch
> - added how to test to the commit message
>
> Changes v5 -> v6:
> - fixed piix3_set_irq_pic()
>
> Changes v4 -> v5:
> - typo
>
> Changes v3 -> v4:
> - use pirq, pci_intx instead of irq_num in piix_pci.c
> - use symbolic constant PIC_NUM_PINS
> - introduced new patch 4/4 which cleans up a bit.
>
> Changes v2 -> v3:
> - s/dummy_for_save_load_compat/pci_irq_levels_vmstate/g
> - move down unused member of pci_irq_levels_vmstate in the structure
> for cache efficiency
>
> Changes v1 -> v2:
> - addressed review comments.
>
> Isaku Yamahata (4):
> pci: add accessor function to get irq levels
> piix_pci: eliminate PIIX3State::pci_irq_levels
> piix_pci: optimize set irq path
> piix_pci: load path clean up
>
> hw/pci.c | 7 +++
> hw/pci.h | 1 +
> hw/piix_pci.c | 129
> ++++++++++++++++++++++++++++++++++++++++++++++-----------
> 3 files changed, 112 insertions(+), 25 deletions(-)