Subject: Re: More on rcons performance woes: pmax profiling
To: R. C. Dowdeswell <elric@imrryr.org>
From: Jonathan Stone <jonathan@DSG.Stanford.EDU>
List: tech-kern
Date: 03/02/1999 03:25:31
I reran a 256 subset of Charles' `output' file.
In an xterm with an rcons-sized font, it took 5.7 seconds.
On rcons, on the same hardware (no reboot), it took 70-some seconds.
Another flat profile (skipping contributors under 1%):
Each sample counts as 0.00390625 seconds.
% cumulative self self total
time seconds seconds calls ms/call ms/call name
65.63 75.82 75.82 255872 0.30 0.30 raster_op_noclip
11.47 89.08 13.26 kernel_text
3.74 93.40 4.32 __mcount
1.93 95.63 2.23 138440 0.02 0.03 vn_read
1.21 97.03 1.40 141211 0.01 0.59 syscall
The dynamic call-graph says the expensive calls to raster_op_noclip()
are coming via rcons_textn():
-----------------------------------------------
75.82 0.00 255872/255872 raster_textn [12]
[13] 77.4 75.82 0.00 255872 raster_op_noclip [13]
-----------------------------------------------
Now, wscons_rops.c uses rcons_textn to do painting, just like rcons
does (via rcons_text(), via rcons_puts()). Which indicates that
nonaccelerated, raster-based text displays will have the same abysmal
performance as rcons.
What's the status of using wscons on ports that currently use rcons--
or which use PROMs to avoid rcons sad performance?