netfilter: conntrack: fix the gc rescheduling delay
[ Upstream commit
95eabdd207024312876d0ebed90b4c977e050e85 ]
Commit
2cfadb761d3d ("netfilter: conntrack: revisit gc autotuning")
changed the eviction rescheduling to the use average expiry of scanned
entries (within 1-60s) by doing:
for (...) {
expires = clamp(nf_ct_expires(tmp), ...);
next_run += expires;
next_run /= 2;
}
The issue is the above will make the average ('next_run' here) more
dependent on the last expiration values than the firsts (for sets > 2).
Depending on the expiration values used to compute the average, the
result can be quite different than what's expected. To fix this we can
do the following:
for (...) {
expires = clamp(nf_ct_expires(tmp), ...);
next_run += (expires - next_run) / ++count;
}
Fixes:
2cfadb761d3d ("netfilter: conntrack: revisit gc autotuning")
Cc: Florian Westphal <fw@strlen.de>
Signed-off-by: Antoine Tenart <atenart@kernel.org>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>