On Thu, Feb 20, 2020 at 01:21:03PM +0000, Emil Velikov wrote: > On Wed, 19 Feb 2020 at 20:35, Ville Syrjala > <ville.syrjala@xxxxxxxxxxxxxxx> wrote: > > > > From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> > > > > struct drm_display_mode is extremely fat. Put it on diet. > > > > Some stats for the whole series: > > > > 64bit sizeof(struct drm_display_mode): > > 200 -> 136 bytes (-32%) > > > > 64bit bloat-o-meter -c drm.ko: > > add/remove: 1/0 grow/shrink: 29/47 up/down: 893/-1544 (-651) > > Function old new delta > > ... > > Total: Before=189430, After=188779, chg -0.34% > > add/remove: 0/0 grow/shrink: 0/0 up/down: 0/0 (0) > > Data old new delta > > Total: Before=11667, After=11667, chg +0.00% > > add/remove: 0/0 grow/shrink: 0/5 up/down: 0/-16896 (-16896) > > RO Data old new delta > > edid_4k_modes 1000 680 -320 > > edid_est_modes 3400 2312 -1088 > > edid_cea_modes_193 5400 3672 -1728 > > drm_dmt_modes 17600 11968 -5632 > > edid_cea_modes_1 25400 17272 -8128 > > Total: Before=71239, After=54343, chg -23.72% > > > > > > 64bit bloat-o-meter drm.ko: > > add/remove: 1/0 grow/shrink: 29/52 up/down: 893/-18440 (-17547) > > ... > > Total: Before=272336, After=254789, chg -6.44% > > > > > > 32bit sizeof(struct drm_display_mode): > > 184 -> 120 bytes (-34%) > > > > 32bit bloat-o-meter -c drm.ko > > add/remove: 1/0 grow/shrink: 19/21 up/down: 743/-1368 (-625) > > Function old new delta > > ... > > Total: Before=172359, After=171734, chg -0.36% > > add/remove: 0/0 grow/shrink: 0/0 up/down: 0/0 (0) > > Data old new delta > > Total: Before=4227, After=4227, chg +0.00% > > add/remove: 0/0 grow/shrink: 0/5 up/down: 0/-16896 (-16896) > > RO Data old new delta > > edid_4k_modes 920 600 -320 > > edid_est_modes 3128 2040 -1088 > > edid_cea_modes_193 4968 3240 -1728 > > drm_dmt_modes 16192 10560 -5632 > > edid_cea_modes_1 23368 15240 -8128 > > Total: Before=59230, After=42334, chg -28.53% > > > > 32bit bloat-o-meter drm.ko: > > add/remove: 1/0 grow/shrink: 19/26 up/down: 743/-18264 (-17521) > > ... > > Total: Before=235816, After=218295, chg -7.43% > > > > > > Some ideas for further reduction: > > - Convert mode->name to a pointer (saves 24/28 bytes in the > > struct but would often require a heap alloc for the name (though > > typical mode name is <10 bytes so still overall win perhaps) > > - Get rid of mode->name entirely? I guess setcrtc & co. is the only > > place where we have to preserve the user provided name, elsewhere > > could pehaps just generate on demand? Not sure how tricky this > > would get. > > The series does some great work, with future work reaching the cache > line for 64bit. > Doing much more than that might be an overkill IMHO. > > In particular, if we change DRM_DISPLAY_MODE_LEN to 24 we get there, > avoiding the heap alloc/calc on demand fun. > While also ensuring the name is sufficiently large for the next decade or so. Unfortunately it's part of the uabi. So can't change it without some risk of userspace breakage. The least demanding option is probably to nuke export_head. We need one bit to replace it, which we can get by either: - stealing from eg. mode->type, or perhaps mode->private_flags - nuke private_flags outright and replace it with a bool for this purpose -- Ville Syrjälä Intel _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
