Re: [PATCH] msi: skip calling pci_find_capability frommsi_set_mask_bits
From: Arnaldo Carvalho de Melo
Date: Tue May 20 2008 - 15:56:47 EST
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@xxxxxxxxxxxxxx>
>
> 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@xxxxxxxxxx>
- Arnaldo
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/