mbox series

[-next,0/2] iommu/iova: optimize the iova rcache

Message ID 20230711025452.35475-1-zhangzekun11@huawei.com
Headers
Series iommu/iova: optimize the iova rcache |

Message

zhangzekun (A) July 11, 2023, 2:54 a.m. UTC 
  The struct of iova rcache has diffcult in dealing with machine with
lots of cpus, because every cpu has a cpu_rcache and they need to
exchange iova in a fixed length buffer rcache->depot, this buffer
can sometimes become a bottle neck of allocating iova from iova_rcache.
The number of iova_cpu_rcache can grow with the number of cpus in
iova_rcache, but the size of rcache->depot will not. The deeper of
rcache->depot can help iova_rcache cache more iovas, and can help
iova_rcache better dealing with senarios in which drivers allocating
and free iovas on different cpu cores. We only let the size of rcache->depot
to grow with the number of cpus which is larger than 32 to avoid potential
performance decrease on machines which don't have much cpus.

Also, it is unsafe to directly free cpu rcache magazines in free_iova_rcaches,
add check before freeing it.

Zhang Zekun (2):
  iommu/iova: Add check for cpu_rcache in free_iova_rcaches
  iommu/iova: allocate iova_rcache->depot dynamicly

 drivers/iommu/iova.c | 36 +++++++++++++++++++++++++++++++-----
 1 file changed, 31 insertions(+), 5 deletions(-)

Comments

zhangzekun (A) July 21, 2023, 1:52 a.m. UTC | #1 
Hi all, does anyone has suggestions for these two patches?

在 2023/7/11 10:54, Zhang Zekun 写道:
> The struct of iova rcache has diffcult in dealing with machine with
> lots of cpus, because every cpu has a cpu_rcache and they need to
> exchange iova in a fixed length buffer rcache->depot, this buffer
> can sometimes become a bottle neck of allocating iova from iova_rcache.
> The number of iova_cpu_rcache can grow with the number of cpus in
> iova_rcache, but the size of rcache->depot will not. The deeper of
> rcache->depot can help iova_rcache cache more iovas, and can help
> iova_rcache better dealing with senarios in which drivers allocating
> and free iovas on different cpu cores. We only let the size of rcache->depot
> to grow with the number of cpus which is larger than 32 to avoid potential
> performance decrease on machines which don't have much cpus.
>
> Also, it is unsafe to directly free cpu rcache magazines in free_iova_rcaches,
> add check before freeing it.
>
> Zhang Zekun (2):
>    iommu/iova: Add check for cpu_rcache in free_iova_rcaches
>    iommu/iova: allocate iova_rcache->depot dynamicly
>
>   drivers/iommu/iova.c | 36 +++++++++++++++++++++++++++++++-----
>   1 file changed, 31 insertions(+), 5 deletions(-)
>