8:56 a.m.
All,
Sorry for the long silence on the mailing list. However, we have made some substantial
progress recently as we prepare for our ISC BOF next week. For those of you at ISC,
please join us from 11 to 12 on Tuesday in Substanz 1&2.
The progress that we have made recently happened because a bunch of us were attending a
German workshop last month at Dagstuhl and had multiple discussions about the benchmark.
Here’s the highlights from what was discussed and the progress that we made at Dagstuhl:
1. General agreement that the IOR-hard, IOR-easy, mdtest-hard, mdtest-easy approach is
appropriate.
2. We should add a ‘find’ command as this is a popular and important workload.
3. The multiple bandwidth measurements should be combined via geometric mean into one
bandwidth.
4. The multiple IOPs measurements should also be combined via geometric mean into one
IOPs.
5. The bandwidth and the IOPs should be multiplied to create one final score.
6. The ranking uses that final score but the webpage can be sorted using other
metrics.
7. The webpage should allow filtering as well so, for example, people can look at only
the HDD results.
8. We should separate the write/create phases from the read/stat phases to help ensure
that caching is avoided
9. Nathan Hjelm volunteered to combine the mdtest and IOR benchmarks into one git repo
and has now done so. This removes the #ifdef mess from mdtest and now they both share the
nice modular IOR backend
So the top-level summary of the benchmark in pseudo-code has become:
# write/create phase
bw1 = ior_easy -write [user supplies their own parameters maximizing data writes that can
be done in 5 minutes]
md1 = md_test_easy -create [user supplies their own parameters maximizing file creates
that can be done in 5 minutes]
bw2 = ior_hard -write [we supply parameters: unaligned strided into single shared file]
md2 = md_test_hard -create [we supply parameters: creates of 3900 byte files into single
shared directory]
# read/stat phase
bw3 = ior_easy -read [cross-node read of everything that was written in bw1]
md3 = md_test_easy -stat [cross-node stat of everything that was created in md1]
bw4 = ior_hard -read
md4 = md_test_hard -stat
# find phase
md5 = [we supply parameters to find a subset of the files that were created in the
tests]
# score phase
bw = geo_mean( bw1 bw2 bw3 bw4)
md = geo_mean( md1 md2 md3 md4 bd5)
total = bw * md
Now we are moving on to precisely define what the parameters should look like for the hard
tests and to create a standard so that people can start running it on their systems. By
doing so, we will define the formal process so we can actually make this an official
benchmark. Please see the attached file in which we’ve started precisely defining these
parameters. Let’s start iterating please on this file to get these parameters correct.
Thanks,
John