Re: [RFC PATCH V2 0/2] swiotlb: Add child io tlb mem support

[Tianyu Lan <ltykernel@gmail.com>]

On 5/2/2022 8:54 PM, Tianyu Lan wrote:
> From: Tianyu Lan <Tianyu.Lan@microsoft.com>
> 
> Traditionally swiotlb was not performance critical because it was only
> used for slow devices. But in some setups, like TDX/SEV confidential
> guests, all IO has to go through swiotlb. Currently swiotlb only has a
> single lock. Under high IO load with multiple CPUs this can lead to
> significant lock contention on the swiotlb lock.
> 
> This patch adds child IO TLB mem support to resolve spinlock overhead
> among device's queues. Each device may allocate IO tlb mem and setup
> child IO TLB mem according to queue number. The number child IO tlb
> mem maybe set up equal with device queue number and this helps to resolve
> swiotlb spinlock overhead among devices and queues.
> 
> Patch 2 introduces IO TLB Block concepts and swiotlb_device_allocate()
> API to allocate per-device swiotlb bounce buffer. The new API Accepts
> queue number as the number of child IO TLB mem to set up device's IO
> TLB mem.

Gentile ping...

Thanks.
> 
> Tianyu Lan (2):
>    swiotlb: Add Child IO TLB mem support
>    Swiotlb: Add device bounce buffer allocation interface
> 
>   include/linux/swiotlb.h |  40 ++++++
>   kernel/dma/swiotlb.c    | 290 ++++++++++++++++++++++++++++++++++++++--
>   2 files changed, 317 insertions(+), 13 deletions(-)
>