Re: [PATCH V4 0/6] IRQ offloading for vDPA

From: Jason Wang <jasowang@redhat.com>
To: Zhu Lingshan <lingshan.zhu@intel.com>,
	alex.williamson@redhat.com, mst@redhat.com, pbonzini@redhat.com,
	sean.j.christopherson@intel.com, wanpengli@tencent.com
Cc: shahafs@mellanox.com, parav@mellanox.com, kvm@vger.kernel.org,
	netdev@vger.kernel.org,
	virtualization@lists.linux-foundation.org, eli@mellanox.com
Subject: Re: [PATCH V4 0/6] IRQ offloading for vDPA
Date: Fri, 31 Jul 2020 11:18:40 +0800	[thread overview]
Message-ID: <d3a12faa-44b5-1c1b-2047-7b39863d82a7@redhat.com> (raw)
In-Reply-To: <20200728042405.17579-1-lingshan.zhu@intel.com>

On 2020/7/28 下午12:23, Zhu Lingshan wrote:
> This series intends to implement IRQ offloading for
> vhost_vdpa.
>
> By the feat of irq forwarding facilities like posted
> interrupt on X86, irq bypass can  help deliver
> interrupts to vCPU directly.
>
> vDPA devices have dedicated hardware backends like VFIO
> pass-throughed devices. So it would be possible to setup
> irq offloading(irq bypass) for vDPA devices and gain
> performance improvements.
>
> In my testing, with this feature, we can save 0.1ms
> in a ping between two VFs on average.
> changes from V3:
> (1)removed vDPA irq allocate/free helpers in vDPA core.
> (2)add a new function get_vq_irq() in struct vdpa_config_ops,
> upper layer driver can use this function to: A. query the
> irq numbner of a vq. B. detect whether a vq is enabled.
> (3)implement get_vq_irq() in ifcvf driver.
> (4)in vhost_vdpa, set_status() will setup irq offloading when
> setting DRIVER_OK, and unsetup when receive !DRIVER_OK.
> (5)minor improvements.

Ok, I think you can go ahead to post a V5. It's not bad to start with 
get_vq_irq() and we can do any changes afterwards if it can work for 
some cases.

Thanks

_______________________________________________
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization