Re: [dpdk-dev] [PATCH v2 0/2] lib/hash: perf improvements for lock-free

[Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>]

> [Snip]
> 
> > The first patch in this series moves the signature comparison before
> > the load- acquire of the key_index. This does not result in any issues
> > because of the full key comparison which is done after the load-acquire of
> the key_index.
> > Performance improvements:
> > Lookup Hit: 6.16%
> > Lookup Miss: 8.54%
> >
> > The second patch in this series, moves the store-release of pData
> > before the store to any hash internal data structures. This is not
> > necessary, but just helps to show the non-dependency between
> > application data and hash table data. On the reader side, the pData is
> > loaded only if the keys match, this provides performance benefits.
> > Performance improvements (with patch 1):
> > Lookup Hit: 6.25%
> > Lookup Miss: 13.97%
> 
> Could you share the commands/data to test this specific performance
> measurement?
The data given here uses hash_readwrite_lf test with 5M entries. The keys used for hit is again 5M.

We also tested this using L3-fwd (note that L3-fwd app needs to be changed to enable lock-free hash code path).
Command: ./examples/l3fwd/build/l3fwd -c 0xc0 -n 1 -- -E -P -p 0x3 --config="(0,0,7),(1,0,6)"
On A72:
Upstream lock-free:
Hit: 11.117/11.168/11.101
Miss: 6.760/6.763/6.764

Upstream lock-free + patches(1,2)
Hit: 11.310/11.276/11.385
Miss: 11.245/11.293/11.281