On Fri, 20 Jun 2008, Peter W. Draper wrote:
> On Fri, 20 Jun 2008, Tim Jenness wrote:
>
>> 27322 (dberry):
>> hds: Speed up the packing and unpacking of Structure Record Vector
>> elements.
>>
>> libraries/hds/dat1_pack_srv.c
>> libraries/hds/dat1_unpack_srv.c
>
> Begs the question, by how much?
>
From an email David wrote to me:
"But even having made this change, vtune was still saying that 25% of
the time is spent in hds_unpack_srv, so I had a look at the
hds_unpack_srv.c file (and the corresponding hds_pack_srv.c file).
These files convert between little endian integers stored in the disk
file and native endian integers needed by the processor. I've
re-worked the algorithm written by Brian to do this, and got a further
decrease in run time from 118 seconds to 87 seconds. I have committed
these changes."
so pretty impressive. I'm a bit confused as to why it needed to convert at
all though because I thought the files were made on an intel linux box so
reading on an intel linux box should not require endian conversion.
--
Tim Jenness
JAC software
http://www.jach.hawaii.edu/~timj
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