linux-kernel - Re: [PATCH v3 26/30] drivers: hv: dxgkrnl: Offer and reclaim allocations

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Message-ID: <20220302142517.kgc5o7ufj2yf4cif@liuwe-devbox-debian-v2>
Date:   Wed, 2 Mar 2022 14:25:17 +0000
From:   Wei Liu <wei.liu@...nel.org>
To:     Iouri Tarassov <iourit@...ux.microsoft.com>
Cc:     kys@...rosoft.com, haiyangz@...rosoft.com, sthemmin@...rosoft.com,
        wei.liu@...nel.org, linux-hyperv@...r.kernel.org,
        linux-kernel@...r.kernel.org, spronovo@...rosoft.com,
        spronovo@...ux.microsoft.com, gregkh@...uxfoundation.org
Subject: Re: [PATCH v3 26/30] drivers: hv: dxgkrnl: Offer and reclaim
 allocations

On Tue, Mar 01, 2022 at 11:46:13AM -0800, Iouri Tarassov wrote:
> Implement ioctls to offer and reclaim compute device allocations:
>   - LX_DXOFFERALLOCATIONS,
>   - LX_DXRECLAIMALLOCATIONS2
> 
> When a user mode driver (UMD) does not need to access an allocation,

What is a "user mode driver" in this context? Is that something that
runs inside the guest?

> it can "offer" it by issuing the LX_DXOFFERALLOCATIONS ioctl.  This
> means that the allocation is not in use and its local device memory
> could be evicted. The freed space could be given to another allocation.
> When the allocation is again needed, the UMD can attempt to"reclaim"
> the allocation by issuing the LX_DXRECLAIMALLOCATIONS2 ioctl. If the
> allocation is still not evicted, the reclaim operation succeeds and no
> other action is required. If the reclaim operation fails, the caller
> must restore the content of the allocation before it can be used by
> the device.
> 
> Signed-off-by: Iouri Tarassov <iourit@...ux.microsoft.com>