Messages in this thread | | | Date | Thu, 18 Sep 2008 04:20:18 +0900 | Subject | Re: [PATCH 03/23] AMD IOMMU: implement lazy IO/TLB flushing | From | FUJITA Tomonori <> |
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On Wed, 17 Sep 2008 18:52:37 +0200 Joerg Roedel <joerg.roedel@amd.com> wrote:
> The IO/TLB flushing on every unmaping operation is the most expensive > part there and not strictly necessary. It is sufficient to do the flush > before any entries are reused. This is patch implements lazy IO/TLB > flushing which does exactly this. > > Signed-off-by: Joerg Roedel <joerg.roedel@amd.com> > --- > Documentation/kernel-parameters.txt | 5 +++++ > arch/x86/kernel/amd_iommu.c | 26 ++++++++++++++++++++++---- > arch/x86/kernel/amd_iommu_init.c | 10 +++++++++- > include/asm-x86/amd_iommu_types.h | 9 +++++++++ > 4 files changed, 45 insertions(+), 5 deletions(-) > > diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt > index c2e00ee..5f0aefe 100644 > --- a/Documentation/kernel-parameters.txt > +++ b/Documentation/kernel-parameters.txt > @@ -284,6 +284,11 @@ and is between 256 and 4096 characters. It is defined in the file > isolate - enable device isolation (each device, as far > as possible, will get its own protection > domain) > + unmap_flush - enable flushing of IO/TLB entries when > + they are unmapped. Otherwise they are > + flushed before they will be reused, which > + is a lot of faster > +
Would it be nice to have consistency of IOMMU parameters?
VT-d also has the kernel-boot option for this lazy flushing trick though VT-d 'strict' option is more vague than 'unmap_flush'
It would be also nice to have consistency of IOMMU behavior.
VT-d enables the lazy flushing trick by default and has the boot option to disable it.
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