[parisc-linux] Progress

John David Anglin dave@hiauly1.hia.nrc.ca
Mon, 22 Nov 1999 13:11:29 -0500 (EST)

> > I tried this and it didn't work.  It looks like __delay() is broken.  The
> > ".balignl" is clearly bogus.
> Oh.  Why ?  The way it is intended is to align the following code to a 64-byte
> boundary (cache lines on current PA2.0 CPUs are 64 bytes, I think) using nops.

Missed this point because of the strange nop.  The current addib loop is 3
instructions.  Alignment to a multiple of 16 should be good enough to
ensure that the loop lies within a cache line.  This would insert a maximum
of 3 nops before the loop.  This would provide a slightly more deterministic

Also, re the BogoMIPS number, I think this should be (loops_per_sec*3)/2000000
(i.e., there is one addib and 0.5 nop instructions per loop when the
number of iterations is large.  The number that is currently printed is

The simple loop "addib,NUV,n .;nop" is slower but more deterministic.  It
only needs an alignment of 8 (at most one nop).  The number of instructions
per loop is 2*N-1.

J. David Anglin                                  dave.anglin@nrc.ca
National Research Council of Canada              (613) 990-0752 (FAX: 952-6605)