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    SubjectRe: [PATCH] msi: skip calling pci_find_capability from msi_set_mask_bits
    Em Mon, May 19, 2008 at 01:11:45PM -0700, Jesse Barnes escreveu:
    > On Sunday, May 18, 2008 9:48 pm Hidetoshi Seto wrote:
    > > Jesse Barnes wrote:
    > > > Since we know MSI is a problem, let's just go with fixing that for now.
    > > > If we find that other caps are also causing problems we can revisit
    > > > caching all of them; the patch is simple enough.
    > >
    > > Humm...
    > > I suppose it can be more simple. How about this patch?
    > >
    > > > everytime handle_edge_irq is called it needs to mask and unmask MSI, and
    > > > that leads to a series of very expensive calls to pci_find_capability
    > >
    > > The position of MSI capability is already cached in the msi_desc when
    > > we enter the msi_set_mask_bits(). Use it instead.
    > >
    > > Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
    >
    > Yeah, this looks really nice. It should also fix Arnaldo's latency problem,
    > and really looks like a bug fix for the MSI code more than anything.
    >
    > Arnaldo, can you take a look & test and ack/nack?

    Tested, works as expected, thanks.

    Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>

    - Arnaldo


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