From: Florian Westphal <fw@strlen.de>
To: <netfilter-devel@vger.kernel.org>
Cc: dcbw@redhat.com, edumzet@google.com
Subject: netfilter: x_tables: speed up iptables-restore
Date: Tue, 10 Oct 2017 12:13:36 +0200 [thread overview]
Message-ID: <20171010101338.14443-1-fw@strlen.de> (raw)
When xt_replace_table assigns the new ruleset pointer, it does
not wait for other processors to finish with old ruleset.
Instead it relies oni the counter sequence lock in get_counters()
to do this.
This works but this is very costly if system is busy as each counter
read operation can possibly be restarted indefinitely.
Instead, lets make xt_replace_table wait until all processors are
known to not use the old ruleset anymore.
This allows to read the old rule set counters without the sequence
lock -- as we already know no cpu is using the ruleset anymore
the counters can't change either.
ipv4/netfilter/arp_tables.c | 22 ++++++++++++++++++++--
ipv4/netfilter/ip_tables.c | 23 +++++++++++++++++++++--
ipv6/netfilter/ip6_tables.c | 22 ++++++++++++++++++++--
netfilter/x_tables.c | 15 ++++++++++++---
4 files changed, 73 insertions(+), 9 deletions(-)
next reply other threads:[~2017-10-10 10:13 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-10 10:13 Florian Westphal [this message]
2017-10-10 10:13 ` [PATCH nf-next 1/2] netfilter: x_tables: make xt_replace_table wait until old rules are not used anymore Florian Westphal
2017-10-10 10:13 ` [PATCH nf-next 2/2] netfilter: x_tables: don't use seqlock when fetching old counters Florian Westphal
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