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the foreground and background colours. In bitblt_text functions, compare values to this cache and don't re-draw the characters if they haven't changed. When invalidating the display, clear this cache in order to force characters to be redrawn; also force full redraws between suspend/resume pairs since odd artifacts can otherwise result. When scrolling the display (which is where most time is spent within the vt driver) this yields a significant performance improvement if most lines are less than the width of the terminal, since this avoids re-drawing blanks on top of blanks. (Note that "re-drawing" here includes writing to the VGA text mode buffer; on virtualized systems this can be extremely slow since it triggers a glyph being rendered onto a 640x480 screen). On a c5.4xlarge EC2 instance (with emulated text mode VGA) this cuts the time spent in vt(4) during the kernel boot from 1200 ms to 700ms; on my laptop (with a 3200x1800 display) the corresponding time is reduced from 970 ms down to 155 ms. Reviewed by: imp, cem Approved by: re (gjb) Relnotes: Significant speedup in vt(4) and the system boot generally. Differential Revision: https://reviews.freebsd.org/D16723 |
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| .. | ||
| colors | ||
| font | ||
| hw | ||
| logo | ||
| vt_buf.c | ||
| vt_consolectl.c | ||
| vt_core.c | ||
| vt_cpulogos.c | ||
| vt_font.c | ||
| vt_sysmouse.c | ||
| vt.h | ||