kernel: scale nf_conntrack_max more reasonably
Use the kernel's built-in formula for computing this value.
The value applied by OpenWRT's sysctl configuration file does not scale
with the available memory, under-using hardware capabilities.
Also, that formula also influences net.netfilter.nf_conntrack_buckets,
which should improve conntrack performance in average (fewer connections
per hashtable bucket).
Backport upstream commit for its effect on the number of connections per
hashtable bucket.
Apply a hack patch to set the RAM size divisor to a more reasonable value (2048,
down from 16384) for our use case, a typical router handling several thousands
of connections.
Signed-off-by: Vincent Pelletier <plr.vincent@gmail.com>
Signed-off-by: Rui Salvaterra <rsalvaterra@gmail.com>
(cherry picked from commit 15fbb91666)
This commit is contained in:
Vincent Pelletier
committed by
Rui Salvaterra
Rui Salvaterra
parent
0179ba7851
commit
0855549b4b
@@ -3,7 +3,6 @@
|
||||
|
||||
net.netfilter.nf_conntrack_acct=1
|
||||
net.netfilter.nf_conntrack_checksum=0
|
||||
net.netfilter.nf_conntrack_max=16384
|
||||
net.netfilter.nf_conntrack_tcp_timeout_established=7440
|
||||
net.netfilter.nf_conntrack_udp_timeout=60
|
||||
net.netfilter.nf_conntrack_udp_timeout_stream=180
|
||||
|
||||
@@ -0,0 +1,100 @@
|
||||
From d532bcd0b2699d84d71a0c71d37157ac6eb3be25 Mon Sep 17 00:00:00 2001
|
||||
Message-Id: <d532bcd0b2699d84d71a0c71d37157ac6eb3be25.1645246598.git.plr.vincent@gmail.com>
|
||||
From: Florian Westphal <fw@strlen.de>
|
||||
Date: Thu, 26 Aug 2021 15:54:19 +0200
|
||||
Subject: [PATCH] netfilter: conntrack: sanitize table size default settings
|
||||
|
||||
conntrack has two distinct table size settings:
|
||||
nf_conntrack_max and nf_conntrack_buckets.
|
||||
|
||||
The former limits how many conntrack objects are allowed to exist
|
||||
in each namespace.
|
||||
|
||||
The second sets the size of the hashtable.
|
||||
|
||||
As all entries are inserted twice (once for original direction, once for
|
||||
reply), there should be at least twice as many buckets in the table than
|
||||
the maximum number of conntrack objects that can exist at the same time.
|
||||
|
||||
Change the default multiplier to 1 and increase the chosen bucket sizes.
|
||||
This results in the same nf_conntrack_max settings as before but reduces
|
||||
the average bucket list length.
|
||||
|
||||
Signed-off-by: Florian Westphal <fw@strlen.de>
|
||||
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
|
||||
---
|
||||
.../networking/nf_conntrack-sysctl.rst | 13 ++++----
|
||||
net/netfilter/nf_conntrack_core.c | 30 +++++++++----------
|
||||
2 files changed, 22 insertions(+), 21 deletions(-)
|
||||
|
||||
--- a/Documentation/networking/nf_conntrack-sysctl.rst
|
||||
+++ b/Documentation/networking/nf_conntrack-sysctl.rst
|
||||
@@ -17,9 +17,8 @@ nf_conntrack_acct - BOOLEAN
|
||||
nf_conntrack_buckets - INTEGER
|
||||
Size of hash table. If not specified as parameter during module
|
||||
loading, the default size is calculated by dividing total memory
|
||||
- by 16384 to determine the number of buckets but the hash table will
|
||||
- never have fewer than 32 and limited to 16384 buckets. For systems
|
||||
- with more than 4GB of memory it will be 65536 buckets.
|
||||
+ by 16384 to determine the number of buckets. The hash table will
|
||||
+ never have fewer than 1024 and never more than 262144 buckets.
|
||||
This sysctl is only writeable in the initial net namespace.
|
||||
|
||||
nf_conntrack_checksum - BOOLEAN
|
||||
@@ -100,8 +99,12 @@ nf_conntrack_log_invalid - INTEGER
|
||||
Log invalid packets of a type specified by value.
|
||||
|
||||
nf_conntrack_max - INTEGER
|
||||
- Size of connection tracking table. Default value is
|
||||
- nf_conntrack_buckets value * 4.
|
||||
+ Maximum number of allowed connection tracking entries. This value is set
|
||||
+ to nf_conntrack_buckets by default.
|
||||
+ Note that connection tracking entries are added to the table twice -- once
|
||||
+ for the original direction and once for the reply direction (i.e., with
|
||||
+ the reversed address). This means that with default settings a maxed-out
|
||||
+ table will have a average hash chain length of 2, not 1.
|
||||
|
||||
nf_conntrack_tcp_be_liberal - BOOLEAN
|
||||
- 0 - disabled (default)
|
||||
--- a/net/netfilter/nf_conntrack_core.c
|
||||
+++ b/net/netfilter/nf_conntrack_core.c
|
||||
@@ -2575,26 +2575,24 @@ int nf_conntrack_init_start(void)
|
||||
spin_lock_init(&nf_conntrack_locks[i]);
|
||||
|
||||
if (!nf_conntrack_htable_size) {
|
||||
- /* Idea from tcp.c: use 1/16384 of memory.
|
||||
- * On i386: 32MB machine has 512 buckets.
|
||||
- * >= 1GB machines have 16384 buckets.
|
||||
- * >= 4GB machines have 65536 buckets.
|
||||
- */
|
||||
nf_conntrack_htable_size
|
||||
= (((nr_pages << PAGE_SHIFT) / 16384)
|
||||
/ sizeof(struct hlist_head));
|
||||
- if (nr_pages > (4 * (1024 * 1024 * 1024 / PAGE_SIZE)))
|
||||
- nf_conntrack_htable_size = 65536;
|
||||
+ if (BITS_PER_LONG >= 64 &&
|
||||
+ nr_pages > (4 * (1024 * 1024 * 1024 / PAGE_SIZE)))
|
||||
+ nf_conntrack_htable_size = 262144;
|
||||
else if (nr_pages > (1024 * 1024 * 1024 / PAGE_SIZE))
|
||||
- nf_conntrack_htable_size = 16384;
|
||||
- if (nf_conntrack_htable_size < 32)
|
||||
- nf_conntrack_htable_size = 32;
|
||||
+ nf_conntrack_htable_size = 65536;
|
||||
|
||||
- /* Use a max. factor of four by default to get the same max as
|
||||
- * with the old struct list_heads. When a table size is given
|
||||
- * we use the old value of 8 to avoid reducing the max.
|
||||
- * entries. */
|
||||
- max_factor = 4;
|
||||
+ if (nf_conntrack_htable_size < 1024)
|
||||
+ nf_conntrack_htable_size = 1024;
|
||||
+ /* Use a max. factor of one by default to keep the average
|
||||
+ * hash chain length at 2 entries. Each entry has to be added
|
||||
+ * twice (once for original direction, once for reply).
|
||||
+ * When a table size is given we use the old value of 8 to
|
||||
+ * avoid implicit reduction of the max entries setting.
|
||||
+ */
|
||||
+ max_factor = 1;
|
||||
}
|
||||
|
||||
nf_conntrack_hash = nf_ct_alloc_hashtable(&nf_conntrack_htable_size, 1);
|
||||
@@ -0,0 +1,25 @@
|
||||
From 804fbb3f2ec9283f7b778e057a68bfff440a0be6 Mon Sep 17 00:00:00 2001
|
||||
From: Rui Salvaterra <rsalvaterra@gmail.com>
|
||||
Date: Wed, 30 Mar 2022 22:51:55 +0100
|
||||
Subject: [PATCH] kernel: ct: size the hashtable more adequately
|
||||
|
||||
To set the default size of the connection tracking hash table, a divider of
|
||||
16384 becomes inadequate for a router handling lots of connections. Divide by
|
||||
2048 instead, making the default size scale better with the available RAM.
|
||||
|
||||
Signed-off-by: Rui Salvaterra <rsalvaterra@gmail.com>
|
||||
---
|
||||
net/netfilter/nf_conntrack_core.c | 2 +-
|
||||
1 file changed, 1 insertion(+), 1 deletion(-)
|
||||
|
||||
--- a/net/netfilter/nf_conntrack_core.c
|
||||
+++ b/net/netfilter/nf_conntrack_core.c
|
||||
@@ -2576,7 +2576,7 @@ int nf_conntrack_init_start(void)
|
||||
|
||||
if (!nf_conntrack_htable_size) {
|
||||
nf_conntrack_htable_size
|
||||
- = (((nr_pages << PAGE_SHIFT) / 16384)
|
||||
+ = (((nr_pages << PAGE_SHIFT) / 2048)
|
||||
/ sizeof(struct hlist_head));
|
||||
if (BITS_PER_LONG >= 64 &&
|
||||
nr_pages > (4 * (1024 * 1024 * 1024 / PAGE_SIZE)))
|
||||
Reference in New Issue
Block a user