diff options
| author | Chia-Yu Chang <chia-yu.chang@nokia-bell-labs.com> | 2025-09-11 13:06:31 +0200 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2025-09-15 16:26:33 -0700 |
| commit | c3426ba2ed6942fe33c75bf17fc7513ba2c6ac64 (patch) | |
| tree | 18d400d36adcfd060ef8ab0a20da85f8930b1784 | |
| parent | tcp: fast path functions later (diff) | |
| download | linux-c3426ba2ed6942fe33c75bf17fc7513ba2c6ac64.tar.gz linux-c3426ba2ed6942fe33c75bf17fc7513ba2c6ac64.zip | |
tcp: reorganize tcp_sock_write_txrx group for variables later
Use the first 3-byte hole at the beginning of the tcp_sock_write_txrx
group for 'noneagle'/'rate_app_limited' to fill in the existing hole
in later patches. Therefore, the group size of tcp_sock_write_txrx is
reduced from 92 + 4 to 91 + 4. In addition, the group size of
tcp_sock_write_rx is changed to 96 to fit in the pahole outcome.
Below are the trimmed pahole outcomes before and after this patch:
[BEFORE THIS PATCH]
struct tcp_sock {
[...]
__cacheline_group_begin__tcp_sock_write_txrx[0]; /* 2521 0 */
/* XXX 3 bytes hole, try to pack */
[...]
struct tcp_options_received rx_opt; /* 2588 24 */
u8 nonagle:4; /* 2612: 0 1 */
u8 rate_app_limited:1; /* 2612: 4 1 */
/* XXX 3 bits hole, try to pack */
__cacheline_group_end__tcp_sock_write_txrx[0]; /* 2613 0 */
/* XXX 3 bytes hole, try to pack */
__cacheline_group_begin__tcp_sock_write_rx[0] __attribute__((__aligned__(8))); /* 2616 0 */
[...]
__cacheline_group_end__tcp_sock_write_rx[0]; /* 2712 0 */
[...]
/* size: 3200, cachelines: 50, members: 161 */
}
[AFTER THIS PATCH]
struct tcp_sock {
[...]
__cacheline_group_begin__tcp_sock_write_txrx[0]; /* 2521 0 */
u8 nonagle:4; /* 2521: 0 1 */
u8 rate_app_limited:1; /* 2521: 4 1 */
/* XXX 3 bits hole, try to pack */
/* XXX 2 bytes hole, try to pack */
[...]
struct tcp_options_received rx_opt; /* 2588 24 */
__cacheline_group_end__tcp_sock_write_txrx[0]; /* 2612 0 */
/* XXX 4 bytes hole, try to pack */
__cacheline_group_begin__tcp_sock_write_rx[0] __attribute__((__aligned__(8))); /* 2616 0 */
[...]
__cacheline_group_end__tcp_sock_write_rx[0]; /* 2712 0 */
[...]
/* size: 3200, cachelines: 50, members: 161 */
}
Signed-off-by: Chia-Yu Chang <chia-yu.chang@nokia-bell-labs.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20250911110642.87529-4-chia-yu.chang@nokia-bell-labs.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
| -rw-r--r-- | include/linux/tcp.h | 4 | ||||
| -rw-r--r-- | net/ipv4/tcp.c | 4 |
2 files changed, 4 insertions, 4 deletions
diff --git a/include/linux/tcp.h b/include/linux/tcp.h index 57e478bfaef2..d103cc0e7a35 100644 --- a/include/linux/tcp.h +++ b/include/linux/tcp.h @@ -285,6 +285,8 @@ struct tcp_sock { * Header prediction flags * 0x5?10 << 16 + snd_wnd in net byte order */ + u8 nonagle : 4,/* Disable Nagle algorithm? */ + rate_app_limited:1; /* rate_{delivered,interval_us} limited? */ __be32 pred_flags; u64 tcp_clock_cache; /* cache last tcp_clock_ns() (see tcp_mstamp_refresh()) */ u64 tcp_mstamp; /* most recent packet received/sent */ @@ -303,8 +305,6 @@ struct tcp_sock { * Options received (usually on last packet, some only on SYN packets). */ struct tcp_options_received rx_opt; - u8 nonagle : 4,/* Disable Nagle algorithm? */ - rate_app_limited:1; /* rate_{delivered,interval_us} limited? */ __cacheline_group_end(tcp_sock_write_txrx); /* RX read-write hotpath cache lines */ diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 7f9c671b1ee0..1f643faa8b93 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -5145,7 +5145,7 @@ static void __init tcp_struct_check(void) /* 32bit arches with 8byte alignment on u64 fields might need padding * before tcp_clock_cache. */ - CACHELINE_ASSERT_GROUP_SIZE(struct tcp_sock, tcp_sock_write_txrx, 92 + 4); + CACHELINE_ASSERT_GROUP_SIZE(struct tcp_sock, tcp_sock_write_txrx, 91 + 4); /* RX read-write hotpath cache lines */ CACHELINE_ASSERT_GROUP_MEMBER(struct tcp_sock, tcp_sock_write_rx, bytes_received); @@ -5162,7 +5162,7 @@ static void __init tcp_struct_check(void) CACHELINE_ASSERT_GROUP_MEMBER(struct tcp_sock, tcp_sock_write_rx, bytes_acked); CACHELINE_ASSERT_GROUP_MEMBER(struct tcp_sock, tcp_sock_write_rx, rcv_rtt_est); CACHELINE_ASSERT_GROUP_MEMBER(struct tcp_sock, tcp_sock_write_rx, rcvq_space); - CACHELINE_ASSERT_GROUP_SIZE(struct tcp_sock, tcp_sock_write_rx, 99); + CACHELINE_ASSERT_GROUP_SIZE(struct tcp_sock, tcp_sock_write_rx, 96); } void __init tcp_init(void) |