[Bridge] [PATCH net-next 0/4] bridge: improve cache utilization
David Miller
davem at davemloft.net
Tue Feb 7 03:53:35 UTC 2017
From: Nikolay Aleksandrov <nikolay at cumulusnetworks.com>
Date: Sat, 4 Feb 2017 18:05:05 +0100
> This is the first set which begins to deal with the bad bridge cache
> access patterns. The first patch rearranges the bridge and port structs
> a little so the frequently (and closely) accessed members are in the same
> cache line. The second patch then moves the garbage collection to a
> workqueue trying to improve system responsiveness under load (many fdbs)
> and more importantly removes the need to check if the matched entry is
> expired in __br_fdb_get which was a major source of false-sharing.
> The third patch is a preparation for the final one which
> If properly configured, i.e. ports bound to CPUs (thus updating "updated"
> locally) then the bridge's HitM goes from 100% to 0%, but even without
> binding we get a win because previously every lookup that iterated over
> the hash chain caused false-sharing due to the first cache line being
> used for both mac/vid and used/updated fields.
>
> Some results from tests I've run:
> (note that these were run in good conditions for the baseline, everything
> ran on a single NUMA node and there were only 3 fdbs)
>
> 1. baseline
> 100% Load HitM on the fdbs (between everyone who has done lookups and hit
> one of the 3 hash chains of the communicating
> src/dst fdbs)
> Overall 5.06% Load HitM for the bridge, first place in the list
>
> 2. patched & ports bound to CPUs
> 0% Local load HitM, bridge is not even in the c2c report list
> Also there's 3% consistent improvement in netperf tests.
Looks great, series applied, thanks!
More information about the Bridge
mailing list