On Thu, 20 Feb 2020 at 14:28, Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> wrote: > > 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. > Right the define is in the uABI. More importantly userspace can provide a drm_mode_modeinfo blob, with a name[32], which we cannot store in the kernel drm_display_mode::name[24]. One might get away with returning -EINVAL if the actual name given by the user is > 24. Since you've found a better way, there's on point in risking it. -Emil _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
