From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sasha Levin Date: Tue, 01 Oct 2019 18:45:26 +0000 Subject: Re: [PATCH v5] video: hyperv: hyperv_fb: Support deferred IO for Hyper-V frame buffer driver Message-Id: <20191001184526.GE8171@sasha-vm> List-Id: References: <20190913060209.3604-1-weh@microsoft.com> In-Reply-To: <20190913060209.3604-1-weh@microsoft.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Wei Hu Cc: "info@metux.net" , "alexandre.belloni@bootlin.com" , Stephen Hemminger , "shc_work@mail.ru" , "gregkh@linuxfoundation.org" , Haiyang Zhang , "rdunlap@infradead.org" , Dexuan Cui , "linux-hyperv@vger.kernel.org" , "fthain@telegraphics.com.au" , Michael Kelley , "baijiaju1990@gmail.com" , "dri-devel@lists.freedesktop.org" , "linux-fbdev@vger.kernel.org" , KY Srinivasan , "lee.jones@linaro.org" , "linux-kernel@vger.kernel.org" On Fri, Sep 13, 2019 at 06:02:55AM +0000, Wei Hu wrote: >Without deferred IO support, hyperv_fb driver informs the host to refresh >the entire guest frame buffer at fixed rate, e.g. at 20Hz, no matter there >is screen update or not. This patch supports deferred IO for screens in >graphics mode and also enables the frame buffer on-demand refresh. The >highest refresh rate is still set at 20Hz. > >Currently Hyper-V only takes a physical address from guest as the starting >address of frame buffer. This implies the guest must allocate contiguous >physical memory for frame buffer. In addition, Hyper-V Gen 2 VMs only >accept address from MMIO region as frame buffer address. Due to these >limitations on Hyper-V host, we keep a shadow copy of frame buffer >in the guest. This means one more copy of the dirty rectangle inside >guest when doing the on-demand refresh. This can be optimized in the >future with help from host. For now the host performance gain from deferred >IO outweighs the shadow copy impact in the guest. > >Signed-off-by: Wei Hu What tree is this based on? I can't get it to apply. -- Thanks, Sasha