linux-kernel - Re: [PATCH vhost v2 0/7] vdpa/mlx5: Optimze MKEY operations

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Message-ID: <fb6b1d3d-c200-479a-941e-1b994757b049@nvidia.com>
Date: Mon, 9 Sep 2024 11:30:22 +0200
From: Dragos Tatulea <dtatulea@...dia.com>
To: "Michael S . Tsirkin" <mst@...hat.com>, Jason Wang <jasowang@...hat.com>,
 Eugenio Perez Martin <eperezma@...hat.com>,
 Si-Wei Liu <si-wei.liu@...cle.com>, virtualization@...ts.linux.dev,
 Gal Pressman <gal@...dia.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
 Parav Pandit <parav@...dia.com>, Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
Subject: Re: [PATCH vhost v2 0/7] vdpa/mlx5: Optimze MKEY operations



On 30.08.24 12:58, Dragos Tatulea wrote:
> This series improves the time of .set_map() operations by parallelizing
> the MKEY creation and deletion for direct MKEYs. Looking at the top
> level MKEY creation/deletion functions, the following improvement can be
> seen:
> 
> |-------------------+-------------|
> | operation         | improvement |
> |-------------------+-------------|
> | create_user_mr()  | 3-5x        |
> | destroy_user_mr() | 8x          |
> |-------------------+-------------|
> 
> The last part of the series introduces lazy MKEY deletion which
> postpones the MKEY deletion to a later point in a workqueue.
> 
> As this series and the previous ones were targeting live migration,
> we can also observe improvements on this front:
> 
> |-------------------+------------------+------------------|
> | Stage             | Downtime #1 (ms) | Downtime #2 (ms) |
> |-------------------+------------------+------------------|
> | Baseline          | 3140             | 3630             |
> | Parallel MKEY ops | 1200             | 2000             |
> | Deferred deletion | 1014             | 1253             |
> |-------------------+------------------+------------------|
> 
> Test configuration: 256 GB VM, 32 CPUs x 2 threads per core, 4 x mlx5
> vDPA devices x 32 VQs (16 VQPs)
> 
> This series must be applied on top of the parallel VQ suspend/resume
> series [0].
> 
> [0] https://lore.kernel.org/all/20240816090159.1967650-1-dtatulea@nvidia.com/
> 
> ---
> v2:
> - Swapped flex array usage for plain zero length array in first patch.
> - Updated code to use Scope-Based Cleanup Helpers where appropriate
>   (only second patch).
> - Added macro define for MTT alignment in first patch.
> - Improved commit messages/comments based on review comments.
> - Removed extra newlines.
Gentle ping for the remaining patches in v2.

Thanks,
Dragos