> From: Sasha Levin <sashal@xxxxxxxxxx> > Sent: Tuesday, October 1, 2019 11:45 AM > To: Wei Hu <weh@xxxxxxxxxxxxx> > > 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 <weh@xxxxxxxxxxxxx> > > What tree is this based on? I can't get it to apply. > > Thanks, > Sasha Please use Wei's v6 patch, which can apply on today's hyperv/linux.git/s hyperv-next branch. Thanks, -- Dexuan
