Re: [PATCH net] conntrack: perform a full scan in gc
flat view
From: Florian Westphal <fw@strlen.de>
Date: 2016-10-18 08:47:18
Also in:
netfilter-devel
Nicolas Dichtel [off-list ref] wrote:
After commit b87a2f9199ea ("netfilter: conntrack: add gc worker to remove
timed-out entries"), netlink conntrack deletion events may be sent with a
huge delay (5 minutes).
There is two ways to evict conntrack:
- during a conntrack lookup;
- during a conntrack dump.
Let's do a full scan of conntrack entries after a period of inactivity
(no conntrack lookup).
CC: Florian Westphal <fw@strlen.de>
Signed-off-by: Nicolas Dichtel <redacted>
---
Here is another proposal to try to fix the problem.
Comments are welcomed,
NicolasHmm, I don't think its good idea in practice. If goal is to avoid starving arbitrary 'dead' ct for too long, then simple ping will defeat the logic here, because...
quoted hunk ↗ jump to hunk
net/netfilter/nf_conntrack_core.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-)diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c index ba6a1d421222..3dbb27bd9582 100644 --- a/net/netfilter/nf_conntrack_core.c +++ b/net/netfilter/nf_conntrack_core.c@@ -87,6 +87,7 @@ static __read_mostly bool nf_conntrack_locks_all; #define GC_MAX_BUCKETS 8192u #define GC_INTERVAL (5 * HZ) #define GC_MAX_EVICTS 256u +static bool gc_full_scan = true; static struct conntrack_gc_work conntrack_gc_work;@@ -511,6 +512,7 @@ ____nf_conntrack_find(struct net *net, const struct nf_conntrack_zone *zone, unsigned int bucket, hsize; begin: + gc_full_scan = false;
... we do periodic lookup (but always in same slot), so no full scan is triggered. If you think its useful, consider sending patch that rescheds worker instantly in case budget expired, otherwise I will do this later this week. [ I am aware doing instant restart might be too late, but at least we would then reap more entries once we stumble upon large number of expired ones ].