I'm lukewarm of this series, but I've got a few comments on it as well
as some questions below.
- In nbdkit we have a function tvdiff_usec (see
common/include/tvdiff.h). Maybe we should use that instead of
microtime?
- Rather than having a single test that does multiple runs (and so
runs for a very long time), it's better to have multiple tests
because they can run in parallel. This is how it could be done (but
see also my comment about benchmarks below).
* Copy original tests/synch-parallel.sh to
tests/synch-parallel-conn-1-request-4096.sh
tests/synch-parallel-conn-1-request-262144.sh
etc. (Or choose better names)
* Each test does:
CONNECTIONS=1 REQUEST_SIZE=4096 ./synch-parallel.sh (etc)
* Original synch-parallel.sh is unchanged, but remove it from TESTS
* Add the new scripts to TESTS
On Sun, Nov 14, 2021 at 09:21:39AM +0200, Nir Soffer wrote:
> I'm working on an application using the sync API. In my tests I see best read
> throughput with 2 nbd connections which is unexpected.
I'm interested in why you're using the synchronous API. I think it'll
inevitably be slower than using the asynch API because you can never
have multiple requests on a single TCP connection.
...
> - The test scripts is much slower now (120 seconds instead of
> 10). We need to to separate the benchmark, running many
> combinations (synch-parallel-bench.sh) and the test, running one
> combination (sync-parallel.sh).
This is too long for tests. I think there are really two conflicting
requirements - you want to benchmark the synchronous API, which is a
worthwhile but separate goal from testing that things are working.
Should we consider having benchmarks in a separate directory or even a
separate git repo? (Separate repo is what I did for libguestfs).
Rich.
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