It should be noted that FAMS is an additional feature to enable mclk switching in more marginal cases than would normally be possible.
Alex On Mon, Jun 13, 2022 at 9:32 AM Vanzylldejong, Harry <[email protected]> wrote: > > [AMD Official Use Only - General] > > Hi Chandan, > > When using Firmware Assisted Memory clock Switching (FAMS), when the memory > clock is switched the frame rate is dropped for at least 1 frame, > sometimes 2-3 frames to make the V-Blank long enough to handle the period > where the GDDR6 memory is unavailable when the memory clock switches. > This drop may be noticeable by gamers, especially if the memory clock wants > to change it's clock rate several times a second, > which is what we observed just on the desktop. > To guarantee best game performance, we disable FAMS during game play. > > Harry > > > -----Original Message----- > From: VURDIGERENATARAJ, CHANDAN <[email protected]> > Sent: June 13, 2022 8:42 AM > To: Michel Dänzer <[email protected]>; Mahfooz, Hamza > <[email protected]>; [email protected] > Cc: Wang, Chao-kai (Stylon) <[email protected]>; Liu, HaoPing (Alan) > <[email protected]>; Li, Sun peng (Leo) <[email protected]>; Lakha, > Bhawanpreet <[email protected]>; Zhuo, Qingqing (Lillian) > <[email protected]>; Siqueira, Rodrigo <[email protected]>; Li, > Roman <[email protected]>; Chiu, Solomon <[email protected]>; Zuo, Jerry > <[email protected]>; Pillai, Aurabindo <[email protected]>; > Vanzylldejong, Harry <[email protected]>; Lin, Wayne > <[email protected]>; Wentland, Harry <[email protected]>; Gutierrez, > Agustin <[email protected]>; Kotarac, Pavle <[email protected]> > Subject: RE: [PATCH 20/23] drm/amd/display: Disables dynamic memory clock > switching in games > > Hi, > > Can you please elaborate on why dynamic memory clock switching can affect > Game performance? > > BR, > Chandan V N > > > >On 2022-06-10 22:52, Hamza Mahfooz wrote: > >> From: Harry VanZyllDeJong <[email protected]> > >> > >> [WHY] > >> Game performace may be affected if dynamic memory clock switching is > >> enabled while playing games. > >> > >> [HOW] > >> Propagate the vrr active state to dirty bit so that on mode set it > >> disables dynamic memory clock switching. > > > >So dynamic memory clock switching will be disabled whenever VRR is enabled? > > > >Note that there is ongoing discussion about how Wayland compositors could > >usefully keep VRR enabled all the time, as opposed to only while >there's a > >fullscreen application like a game. So "VRR is enabled" likely won't be > >equivalent to "game is running" in the long term. > > > > > -- > Earthling Michel Dänzer | > https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fredhat.com%2F&data=05%7C01%7Cchandan.vurdigerenataraj%40amd.com%7C005764271a144b5832c408da4d293dee%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637907136793233201%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=NSiOtjfwkelxkZMRFLzFs1mFPvosOFZnqrcNvRb9J6E%3D&reserved=0 > Libre software enthusiast | Mesa and Xwayland developer
