On Wed, 20 Jun 2007, Kris Kennaway wrote:
On Wed, Jun 20, 2007 at 10:24:01AM -0400, David Cross wrote:
Machine 2:
time sed -f
/usr/src/gnu/usr.bin/groff/tmac/../../../../contrib/groff/tmac/strip.sed
/usr/src/gnu/usr.bin/groff/tmac/../../../../contrib/groff/tmac/doc-common
/dev/null
real 0m4.506s
user 0m4.167s
sys 0m0.000s
Yes... you read that right... almost 400 _TIMES_ slower. WTF..
Where should I be looking?
Try ktracing to see what it is doing (although sys time = 0 says it's
all in userland). So maybe gprof or pmc. Also double check the
kernel configs are identical and malloc debugging is disabled.
I ktraced it, its basically just writing data, averaging about 20 bytes
per write (that's how I came up with the bs= number on the dd line, trying
to simulate it. I agree that it _SEEMS_ to be userland, BUT what I am
suspecting is that the slowdown is in the transition between kernel and
userland, but I am unsure how to check this. Kernel config is "SMP" on
both.
I will note its also more then just sed, the whole machine FEELs sluggish,
that's just the clearest example I could show.
--
David E. Cross
That being said, dd SHOULD have the same problem. I will work on
gprof-ing it now.
Kris
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