Messages in this thread | | | Date | Mon, 29 Sep 2008 10:56:47 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH 3/3] x86/iommu: use __GFP_ZERO instead of memset for GART |
| |
* Joerg Roedel <joerg.roedel@amd.com> wrote:
> On Sat, Sep 27, 2008 at 08:18:55PM +0200, Ingo Molnar wrote: > > > > another thing: > > > > How hard would it be to add an CONFIG_IOMMU_DEBUG option that forces as > > many DMA requests to go via the IOMMU as possible? > > > > This slows things down of course so it's only for debugging - but it > > also makes sure that we utilize the IOMMU code to the maximum - which is > > not normally the case. > > > > Would be nice to have it .config driven (default-disabled), so that > > -tip's randconfig testing can stumble upon it every now and then. I've > > got GART test-systems - this way we could find certain types of IOMMU > > breakages sooner. > > For AMD IOMMU I disabled the round-robin allocator to stress-test the > code. This means that the address allocation bitmap is always > traversed from the first bit. In consequence the TLB flushing is > stressed a lot (both in hardware and software) because the same DMA > addresses are used again and again. For testing I hardcoded it into > the driver but I can also make it depend on CONFIG_IOMMU_DEBUG.
yes - could you please make a new option for it, CONFIG_IOMMU_DEBUG_FORCE=y or so - and cover all iommus that support it?
Ingo
| |