On Fri, Aug 02, 2024 at 09:14:28AM -0400, Michael S. Tsirkin wrote: > On Fri, Aug 02, 2024 at 10:20:17AM +0300, Dragos Tatulea wrote: > > This series parallelizes the mlx5_vdpa device suspend and resume > > operations through the firmware async API. The purpose is to reduce live > > migration downtime. > > > > The series starts with changing the VQ suspend and resume commands > > to the async API. After that, the switch is made to issue multiple > > commands of the same type in parallel. > > > > Finally, a bonus improvement is thrown in: keep the notifierd enabled > > during suspend but make it a NOP. Upon resume make sure that the link > > state is forwarded. This shaves around 30ms per device constant time. > > > > For 1 vDPA device x 32 VQs (16 VQPs), on a large VM (256 GB RAM, 32 CPUs > > x 2 threads per core), the improvements are: > > > > +-------------------+--------+--------+-----------+ > > | operation | Before | After | Reduction | > > |-------------------+--------+--------+-----------| > > | mlx5_vdpa_suspend | 37 ms | 2.5 ms | 14x | > > | mlx5_vdpa_resume | 16 ms | 5 ms | 3x | > > +-------------------+--------+--------+-----------+ > > > > Note for the maintainers: > > The first patch contains changes for mlx5_core. This must be applied > > into the mlx5-vhost tree [0] first. Once this patch is applied on > > mlx5-vhost, the change has to be pulled from mlx5-vdpa into the vhost > > tree and only then the remaining patches can be applied. > > Or maintainer just acks it and I apply directly. We can do it, but there is a potential to create a conflict between your tree and netdev for whole cycle, which will be a bit annoying. Easiest way to avoid this is to have a shared branch, but in august everyone is on vacation, so it will be probably fine to apply such patch directly. Thanks > > Let me know when all this can happen. > > > [0] https://git.kernel.org/pub/scm/linux/kernel/git/mellanox/linux.git/log/?h=mlx5-vhost > > > > Dragos Tatulea (7): > > net/mlx5: Support throttled commands from async API > > vdpa/mlx5: Introduce error logging function > > vdpa/mlx5: Use async API for vq query command > > vdpa/mlx5: Use async API for vq modify commands > > vdpa/mlx5: Parallelize device suspend > > vdpa/mlx5: Parallelize device resume > > vdpa/mlx5: Keep notifiers during suspend but ignore > > > > drivers/net/ethernet/mellanox/mlx5/core/cmd.c | 21 +- > > drivers/vdpa/mlx5/core/mlx5_vdpa.h | 7 + > > drivers/vdpa/mlx5/net/mlx5_vnet.c | 435 +++++++++++++----- > > 3 files changed, 333 insertions(+), 130 deletions(-) > > > > -- > > 2.45.2 > >
