[PATCH] LMDB full patch set

Garming Sam garming at catalyst.net.nz
Thu May 17 04:15:57 UTC 2018

Hi metze,

The last time I tested this I found the following numbers for
straightforward single threaded operations (make -j perftest
TESTS=medley). The numbers did not vary significantly, although there
were some searches which were noticeably faster in LMDB from my
recollection. This was done with NO_SYNC, so actually I suspect you
would probably notice more of a difference with it off (as LMDB should
be doing less fcntl locks).

I suspect Joe's concurrent stress-testing would tell us more about how
it behaves under real load -- we definitely should block less now,
although not as little as LMDB fully allows due to other requirements.
There are also some selftest interactions that mean that socket wrapper
can actually affect some of these results, so it's not a true straight
comparison of the different backends -- although I did try manage to get
the LMDB run to be under (network and user) namespaces (which I think is
the recorded data here) rather than socket wrapper. Socket wrapper
intercepting write calls seemed to make LMDB perform maybe 10% worse.

One other thing I noticed is that relative performance as the size of
the database grows, looks to be better with LMDB. At the 2k user level,
we might be slightly worse, while at the 6k user level there might be a
10% improvement. At the 50k or 100k user level, I suspect the difference
is probably quite wide.



On 17/05/18 03:09, Stefan Metzmacher via samba-technical wrote:
> Hi,
>>> Without the limits from buildnice, a full autobuild on sn-devel passed.
>>> Metze, Can you please indicate what your need next to approve this?
> Do you actually have some performance numbers for the new code?
> metze

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