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Date: Mon, 8 May 2023 18:53:14 +0200
From: Christophe JAILLET <christophe.jaillet@...adoo.fr>
To: Pablo Neira Ayuso <pablo@...filter.org>,
Jozsef Kadlecsik <kadlec@...filter.org>,
Florian Westphal <fw@...len.de>,
"David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>
Cc: linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
Christophe JAILLET <christophe.jaillet@...adoo.fr>,
netfilter-devel@...r.kernel.org, coreteam@...filter.org,
netdev@...r.kernel.org
Subject: [PATCH net-next] netfilter: Reorder fields in 'struct nf_conntrack_expect'
Group some variables based on their sizes to reduce holes.
On x86_64, this shrinks the size of 'struct nf_conntrack_expect' from 264
to 256 bytes.
This structure deserve a dedicated cache, so reducing its size looks nice.
Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
---
Using pahole
Before:
======
struct nf_conntrack_expect {
struct hlist_node lnode; /* 0 16 */
struct hlist_node hnode; /* 16 16 */
struct nf_conntrack_tuple tuple; /* 32 40 */
/* --- cacheline 1 boundary (64 bytes) was 8 bytes ago --- */
struct nf_conntrack_tuple_mask mask; /* 72 20 */
/* XXX 4 bytes hole, try to pack */
void (*expectfn)(struct nf_conn *, struct nf_conntrack_expect *); /* 96 8 */
struct nf_conntrack_helper * helper; /* 104 8 */
struct nf_conn * master; /* 112 8 */
struct timer_list timeout; /* 120 88 */
/* --- cacheline 3 boundary (192 bytes) was 16 bytes ago --- */
refcount_t use; /* 208 4 */
unsigned int flags; /* 212 4 */
unsigned int class; /* 216 4 */
union nf_inet_addr saved_addr; /* 220 16 */
union nf_conntrack_man_proto saved_proto; /* 236 2 */
/* XXX 2 bytes hole, try to pack */
enum ip_conntrack_dir dir; /* 240 4 */
/* XXX 4 bytes hole, try to pack */
struct callback_head rcu __attribute__((__aligned__(8))); /* 248 16 */
/* size: 264, cachelines: 5, members: 15 */
/* sum members: 254, holes: 3, sum holes: 10 */
/* forced alignments: 1, forced holes: 1, sum forced holes: 4 */
/* last cacheline: 8 bytes */
} __attribute__((__aligned__(8)));
After:
=====
struct nf_conntrack_expect {
struct hlist_node lnode; /* 0 16 */
struct hlist_node hnode; /* 16 16 */
struct nf_conntrack_tuple tuple; /* 32 40 */
/* --- cacheline 1 boundary (64 bytes) was 8 bytes ago --- */
struct nf_conntrack_tuple_mask mask; /* 72 20 */
refcount_t use; /* 92 4 */
unsigned int flags; /* 96 4 */
unsigned int class; /* 100 4 */
void (*expectfn)(struct nf_conn *, struct nf_conntrack_expect *); /* 104 8 */
struct nf_conntrack_helper * helper; /* 112 8 */
struct nf_conn * master; /* 120 8 */
/* --- cacheline 2 boundary (128 bytes) --- */
struct timer_list timeout; /* 128 88 */
/* --- cacheline 3 boundary (192 bytes) was 24 bytes ago --- */
union nf_inet_addr saved_addr; /* 216 16 */
union nf_conntrack_man_proto saved_proto; /* 232 2 */
/* XXX 2 bytes hole, try to pack */
enum ip_conntrack_dir dir; /* 236 4 */
struct callback_head rcu __attribute__((__aligned__(8))); /* 240 16 */
/* size: 256, cachelines: 4, members: 15 */
/* sum members: 254, holes: 1, sum holes: 2 */
/* forced alignments: 1 */
} __attribute__((__aligned__(8)));
---
include/net/netfilter/nf_conntrack_expect.h | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)
diff --git a/include/net/netfilter/nf_conntrack_expect.h b/include/net/netfilter/nf_conntrack_expect.h
index 0855b60fba17..cf0d81be5a96 100644
--- a/include/net/netfilter/nf_conntrack_expect.h
+++ b/include/net/netfilter/nf_conntrack_expect.h
@@ -26,6 +26,15 @@ struct nf_conntrack_expect {
struct nf_conntrack_tuple tuple;
struct nf_conntrack_tuple_mask mask;
+ /* Usage count. */
+ refcount_t use;
+
+ /* Flags */
+ unsigned int flags;
+
+ /* Expectation class */
+ unsigned int class;
+
/* Function to call after setup and insertion */
void (*expectfn)(struct nf_conn *new,
struct nf_conntrack_expect *this);
@@ -39,15 +48,6 @@ struct nf_conntrack_expect {
/* Timer function; deletes the expectation. */
struct timer_list timeout;
- /* Usage count. */
- refcount_t use;
-
- /* Flags */
- unsigned int flags;
-
- /* Expectation class */
- unsigned int class;
-
#if IS_ENABLED(CONFIG_NF_NAT)
union nf_inet_addr saved_addr;
/* This is the original per-proto part, used to map the
--
2.34.1
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