Re: [PATCH 1/2]Add Variable Page Size and IA64 Support in Intel IOMMU: Generic Part
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- To: "Yu, Fenghua" <fenghua.yu@xxxxxxxxx>
- Subject: Re: [PATCH 1/2]Add Variable Page Size and IA64 Support in Intel IOMMU: Generic Part
- From: Ingo Molnar <mingo@xxxxxxx>
- Date: Fri, 3 Oct 2008 10:54:50 +0200
- Cc: Bjorn Helgaas <bjorn.helgaas@xxxxxx>, "Luck, Tony" <tony.luck@xxxxxxxxx>, Jesse Barnes <jbarnes@xxxxxxxxxxxxxxxx>, David Woodhouse <dwmw2@xxxxxxxxxxxxx>, Avi Kivity <avi@xxxxxxxxxx>, Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>, LKML <linux-kernel@xxxxxxxxxxxxxxx>, "linux-ia64@xxxxxxxxxxxxxxx" <linux-ia64@xxxxxxxxxxxxxxx>
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- List-id: <linux-ia64.vger.kernel.org>
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- User-agent: Mutt/1.5.18 (2008-05-17)
* Yu, Fenghua <fenghua.yu@xxxxxxxxx> wrote:
> >What's this all about? Why do we need #ifdef CONFIG_IA64 here?
> >Doesn't x86 provide its own readq/writeq implementation?
>
> This is a comment from Bjorn.
>
> In my patch, one readq/one writeq are working faster than two
> readl/two writel on IA64. X86 uses two readl/two writel so that the
> code works on both x86 and x86-64 although Intel IOMMU only has x86-64
> version currently. dmar_readq() and dmar_writeq() are in moderate
> performance critical path.
>
> Do you think my current implementation is ok to have #ifdef
> CONFIG_IA64 here? Or I can change X86 to use readq/writeq as well or
> IA64 uses two readl/two writel for clean code?
yes, clean code is very much preferred for a small detail like this.
Ingo
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