Messages in this thread | | | Date | Mon, 8 Apr 2024 09:39:30 -0700 | From | Jacob Pan <> | Subject | Re: [PATCH v2] iommu/vt-d: Allocate DMAR fault interrupts locally |
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Hi Kevin,
On Mon, 8 Apr 2024 09:00:05 +0000, "Tian, Kevin" <kevin.tian@intel.com> wrote:
> > From: Baolu Lu <baolu.lu@linux.intel.com> > > Sent: Monday, April 8, 2024 3:22 PM > > > > On 2024/4/8 14:54, Tian, Kevin wrote: > > >> From: Dimitri Sivanich <sivanich@hpe.com> > > >> Sent: Friday, March 22, 2024 4:51 AM > > >> > > >> The Intel IOMMU code currently tries to allocate all DMAR fault > > >> interrupt vectors on the boot cpu. On large systems with high DMAR > > >> counts this results in vector exhaustion, and most of the vectors > > >> are not initially allocated socket local. > > >> > > >> Instead, have a cpu on each node do the vector allocation for the > > >> DMARs > > on > > >> that node. The boot cpu still does the allocation for its node > > >> during its boot sequence. > > >> > > >> Signed-off-by: Dimitri Sivanich <sivanich@hpe.com> > > > > > > Reviewed-by: Kevin Tian <kevin.tian@intel.com> > > > > > > > Kevin, > > > > Jacob has another proposal which shares the irq among all IOMMUs. > > > > https://lore.kernel.org/linux-iommu/20240403234548.989061-1- > > jacob.jun.pan@linux.intel.com/ > > > > How do you like this? > > > > I'm a bit concerning about the need of looping all IOMMU's in DMAR > irqchip mask/unmask handlers. this one sounds simpler to me. The difference is that with this patch, we still burn a few vectors on BSP and the leading CPU of each socket.
e.g. on sapphire rapids, we lose 8 vectors to DMAR fault IRQ on BSP.
Thanks,
Jacob
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