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Message-ID: <20230310034934-mutt-send-email-mst@kernel.org>
Date: Fri, 10 Mar 2023 03:49:56 -0500
From: "Michael S. Tsirkin" <mst@...hat.com>
To: Xie Yongji <xieyongji@...edance.com>
Cc: jasowang@...hat.com, tglx@...utronix.de, hch@....de,
virtualization@...ts.linux-foundation.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 00/11] VDUSE: Improve performance
On Tue, Feb 28, 2023 at 05:40:59PM +0800, Xie Yongji wrote:
> Hi all,
>
> This series introduces some ways to improve VDUSE performance.
Pls fix warnings reported by 0-day infra, dropping this for now.
> Patch 1 ~ 6 bring current interrupt affinity spreading mechanism
> to vduse device and make it possible for the virtio-blk driver
> to build the blk-mq queues based on it. This would be useful to
> mitigate the virtqueue lock contention in virtio-blk driver. In
> our test, with those patches, we could get ~50% improvement (600k
> iops -> 900k iops) when using per-cpu virtqueue.
>
> Patch 7 adds a sysfs interface for each vduse virtqueue to change
> the affinity for IRQ callback. It would be helpful for performance
> tuning when the affinity mask contains more than one CPU.
>
> Patch 8 ~ 9 associate an eventfd to the vdpa callback so that
> we can signal it directly during irq injection without scheduling
> an additional workqueue thread to do that.
>
> Patch 10, 11 add a sysfs interface to support specifying bounce
> buffer size in virtio-vdpa case. The high throughput workloads
> can benefit from it. And we can also use it to reduce the memory
> overhead for small throughput workloads.
>
> Please review, thanks!
>
> V2 to V3:
> - Rebased to newest kernel tree
> - Export group_cpus_evenly() instead of irq_create_affinity_masks() [MST]
> - Remove the sysfs for workqueue control [Jason]
> - Associate an eventfd to the vdpa callback [Jason]
> - Signal the eventfd directly in vhost-vdpa case [Jason]
> - Use round-robin to spread IRQs between CPUs in the affinity mask [Jason]
> - Handle the cpu hotplug case on IRQ injection [Jason]
> - Remove effective IRQ affinity and balance mechanism for IRQ allocation
>
> V1 to V2:
> - Export irq_create_affinity_masks()
> - Add set/get_vq_affinity and set_irq_affinity callbacks in vDPA
> framework
> - Add automatic irq callback affinity support in VDUSE driver [Jason]
> - Add more backgrounds information in commit log [Jason]
> - Only support changing effective affinity when the value is a subset
> of the IRQ callback affinity mask
>
> Xie Yongji (11):
> lib/group_cpus: Export group_cpus_evenly()
> vdpa: Add set/get_vq_affinity callbacks in vdpa_config_ops
> vdpa: Add set_irq_affinity callback in vdpa_config_ops
> vduse: Refactor allocation for vduse virtqueues
> vduse: Support automatic irq callback affinity
> vduse: Support set/get_vq_affinity callbacks
> vduse: Add sysfs interface for irq callback affinity
> vdpa: Add eventfd for the vdpa callback
> vduse: Signal interrupt's eventfd directly in vhost-vdpa case
> vduse: Delay iova domain creation
> vduse: Support specifying bounce buffer size via sysfs
>
> drivers/vdpa/vdpa_user/vduse_dev.c | 490 +++++++++++++++++++++++++----
> drivers/vhost/vdpa.c | 2 +
> drivers/virtio/virtio_vdpa.c | 33 ++
> include/linux/vdpa.h | 25 ++
> lib/group_cpus.c | 1 +
> 5 files changed, 488 insertions(+), 63 deletions(-)
>
> --
> 2.20.1
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