- use a more accurate and more efficient method of compensating for
overheads. The old method counted too much time against leaf
functions.
- normally use the Pentium timestamp counter if available.
On Pentiums, the times are now accurate to within a couple of cpu
clock cycles per function call in the (unlikely) event that there
are no cache misses in or caused by the profiling code.
- optionally use an arbitrary Pentium event counter if available.
- optionally regress to using the i8254 counter.
- scaled the i8254 counter by a factor of 128. Now the i8254 counters
overflow slightly faster than the TSC counters for a 150MHz Pentium :-)
(after about 16 seconds). This is to avoid fractional overheads.
files.i386:
permon.c temporarily has to be classified as a profiling-routine
because a couple of functions in it may be called from profiling code.
options.i386:
- I586_CTR_GUPROF is currently unused (oops).
- I586_PMC_GUPROF should be something like 0x70000 to enable (but not
use unless prof_machdep.c is changed) support for Pentium event
counters. 7 is a control mode and the counter number 0 is somewhere
in the 0000 bits (see perfmon.h for the encoding).
profile.h:
- added declarations.
- cleaned up separation of user mode declarations.
prof_machdep.c:
Mostly clock-select changes. The default clock can be changed by
editing kmem. There should be a sysctl for this.
subr_prof.c:
- added copyright.
- calibrate overheads for the new method.
- documented new method.
- fixed races and and machine dependencies in start/stop code.
mcount.c:
Use the new overhead compensation method.
gmon.h:
- changed GPROF4 counter type from unsigned to int. Oops, this should
be machine-dependent and/or int32_t.
- reorganized overhead counters.
Submitted by: Pentium event counter changes mostly by wollman
Fixed BCD declarations. They didn't match their definitions...
libkern.h, bcd.c:
KNFised. `indent' worked 99% perfectly on bcd.c. It worked 99%
_imperfectly_ on subr_prf.c.
looking at a high resolution clock for each of the following events:
function call, function return, interrupt entry, interrupt exit,
and interesting branches. The differences between the times of
these events are added at appropriate places in a ordinary histogram
(as if very fast statistical profiling sampled the pc at those
places) so that ordinary gprof can be used to analyze the times.
gmon.h:
Histogram counters need to be 4 bytes for microsecond resolutions.
They will need to be larger for the 586 clock.
The comments were vax-centric and wrong even on vaxes. Does anyone
disagree?
gprof4.c:
The standard gprof should support counters of all integral sizes
and the size of the counter should be in the gmon header. This
hack will do until then. (Use gprof4 -u to examine the results
of non-statistical profiling.)
config/*:
Non-statistical profiling is configured with `config -pp'.
`config -p' still gives ordinary profiling.
kgmon/*:
Non-statistical profiling is enabled with `kgmon -B'. `kgmon -b'
still enables ordinary profiling (and distables non-statistical
profiling) if non-statistical profiling is configured.
libkern.a are now specified by listing their source files in
files.${MACHINE}. The list is machine-dependent to save space.
All the necessary object for each machine must be linked into the
kernel in case an lkm wants one.
(on an i486, 10 cycles (+ cache misses) instead of 15). The
change should be a no-op if the compiler is any good. The best
possible i*86 code for the same algorithm is only 1 more cycle
faster on i486's so I don't want to bother implementing an
assembler version.
scanc() is a bottleneck for OPOST processing. It is naturally
about 4 times as slow as bcopy() on 32-bit systems.
I couldn't find a better way to avoid compiler warnings about
redundant and/or inconsistent declaration of ffs(). I'd like to
be able to declare prototypes in general headers without committing
to implementing them as `static inline' or `extern', but there
seems to be no way to do this with gcc-2.6.1. E.g.,
int foo(void);
static __inline int foo(void) { return 1; }
causes a warning about the linkage mismatch, while the opposite
order causes a warning about the redundant declaration.
that add it too, and end up fighting an unwanted battle right now,
I'm just going to back away from both and start including my own private
copies of everything. I'm not going to use _anything_ from libkern
until we decide its fate.
I just know I'm going to get flamed for adding for the miserable
abortion that is libkern, but what am I supposed to do? At least I
didn't drag in the ctype stuff! :-)
"gcc -Wstrict-prototypes" doesn't emit warnings about them.
Write each min/max functions on a single line so that the similarity and
triviality of the functions is more obvious.
Put the quad min/max functions in the correct place (aphabetical order).
The u_quad min/max functions are missing. Only 3 or 4 of the min/max
functions are actually used. sys/socketvar.h ``should use "lmin" but
it doesn't exist now''. lmin does exist now, but isn't used. Since we
depend on gcc for `inline', perhaps we should depend on it for __typeof
and function-expressions and use only macros min() and max() that work
for any types (I'm not sure how to handle mixed types).
