lkml.org 
[lkml]   [2008]   [Sep]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [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


\
 
 \ /
  Last update: 2008-09-29 10:59    [W:0.064 / U:0.384 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site