Rod, Quincey asked me to look at the problem you reported. I ran your code and saw 1.8 library is much slower than 1.6 library. I'll let you know once I find the reason.
Thanks. Ray On Jun 24, 2011, at 9:08 AM, Rod Cook wrote: > Quincey > > I was surprised as well, especially by how much slower it was. I tried > changing to 1.8.3 when it came out but found that my application was a lot > slower, I didn't have the time then to investigate further and I went back to > 1.6.5. I have now found the same problem with 1.8.7. > > My application uses HDF via a library of wrapper rountines. I wrote a timing > program using this library that mimicked the application and found that it > was about 500 times slower with 1.8.7. When I removed the code that > created/used attributes the times for 1.6.5 and 1.8.7 were similar. I have > cut and pasted bits from my library into some code I can send you, 1.8.7 is > about 40 times slower for this code -- the use of datasets and attributes in > this example are much simpler than in my timing program or application. The > code contains a call to the function write_attribute, if this call is removed > the times for 1.6.5 and 1.8.7 are similar. > > I suspect that I've misused/misunderstood HDF in some way but got away with > it for 1.6.5. > > Thanks for your help > > Rod > > On 23/06/2011 16:50, Quincey Koziol wrote: >> Hi Rod, >> >> On Jun 23, 2011, at 6:09 AM, Rod Cook wrote: >> >>> I am currently changing from 1.6.5 to 1.8.7 and my application is 500 times >>> slower with 1.8.7. I have narrowed the cause down to the creation (and >>> use) of attributes. The application that can generate 1000's of small >>> attributes (references to a dataset) attached to a single object. I would >>> be grateful for any help and advice. >> Hmm, I'm surprised that things got slower in this area. Can you send a >> simple C program that works with both versions and demonstrates the slowdown? >> >> Quincey >> >> >> _______________________________________________ >> Hdf-forum is for HDF software users discussion. >> [email protected] >> http://mail.hdfgroup.org/mailman/listinfo/hdf-forum_hdfgroup.org >> >> > > <hdftiming.c>_______________________________________________ > Hdf-forum is for HDF software users discussion. > [email protected] > http://mail.hdfgroup.org/mailman/listinfo/hdf-forum_hdfgroup.org _______________________________________________ Hdf-forum is for HDF software users discussion. [email protected] http://mail.hdfgroup.org/mailman/listinfo/hdf-forum_hdfgroup.org
