From: Vincent Mailhol struct raw_sock has several holes. Reorder the fields to save 8 bytes. Statistics before: $ pahole --class_name=raw_sock net/can/raw.o struct raw_sock { struct sock sk __attribute__((__aligned__(8))); /* 0 776 */ /* XXX last struct has 1 bit hole */ /* --- cacheline 12 boundary (768 bytes) was 8 bytes ago --- */ int ifindex; /* 776 4 */ /* XXX 4 bytes hole, try to pack */ struct net_device * dev; /* 784 8 */ netdevice_tracker dev_tracker; /* 792 0 */ struct list_head notifier; /* 792 16 */ unsigned int bound:1; /* 808: 0 4 */ unsigned int loopback:1; /* 808: 1 4 */ unsigned int recv_own_msgs:1; /* 808: 2 4 */ unsigned int fd_frames:1; /* 808: 3 4 */ unsigned int xl_frames:1; /* 808: 4 4 */ unsigned int join_filters:1; /* 808: 5 4 */ /* XXX 2 bits hole, try to pack */ /* Bitfield combined with next fields */ struct can_raw_vcid_options raw_vcid_opts; /* 809 4 */ /* XXX 3 bytes hole, try to pack */ canid_t tx_vcid_shifted; /* 816 4 */ canid_t rx_vcid_shifted; /* 820 4 */ canid_t rx_vcid_mask_shifted; /* 824 4 */ int count; /* 828 4 */ /* --- cacheline 13 boundary (832 bytes) --- */ struct can_filter dfilter; /* 832 8 */ struct can_filter * filter; /* 840 8 */ can_err_mask_t err_mask; /* 848 4 */ /* XXX 4 bytes hole, try to pack */ struct uniqframe * uniq; /* 856 8 */ /* size: 864, cachelines: 14, members: 20 */ /* sum members: 852, holes: 3, sum holes: 11 */ /* sum bitfield members: 6 bits, bit holes: 1, sum bit holes: 2 bits */ /* member types with bit holes: 1, total: 1 */ /* forced alignments: 1 */ /* last cacheline: 32 bytes */ } __attribute__((__aligned__(8))); ...and after: $ pahole --class_name=raw_sock net/can/raw.o struct raw_sock { struct sock sk __attribute__((__aligned__(8))); /* 0 776 */ /* XXX last struct has 1 bit hole */ /* --- cacheline 12 boundary (768 bytes) was 8 bytes ago --- */ struct net_device * dev; /* 776 8 */ netdevice_tracker dev_tracker; /* 784 0 */ struct list_head notifier; /* 784 16 */ int ifindex; /* 800 4 */ unsigned int bound:1; /* 804: 0 4 */ unsigned int loopback:1; /* 804: 1 4 */ unsigned int recv_own_msgs:1; /* 804: 2 4 */ unsigned int fd_frames:1; /* 804: 3 4 */ unsigned int xl_frames:1; /* 804: 4 4 */ unsigned int join_filters:1; /* 804: 5 4 */ /* XXX 2 bits hole, try to pack */ /* Bitfield combined with next fields */ struct can_raw_vcid_options raw_vcid_opts; /* 805 4 */ /* XXX 3 bytes hole, try to pack */ canid_t tx_vcid_shifted; /* 812 4 */ canid_t rx_vcid_shifted; /* 816 4 */ canid_t rx_vcid_mask_shifted; /* 820 4 */ can_err_mask_t err_mask; /* 824 4 */ int count; /* 828 4 */ /* --- cacheline 13 boundary (832 bytes) --- */ struct can_filter dfilter; /* 832 8 */ struct can_filter * filter; /* 840 8 */ struct uniqframe * uniq; /* 848 8 */ /* size: 856, cachelines: 14, members: 20 */ /* sum members: 852, holes: 1, sum holes: 3 */ /* sum bitfield members: 6 bits, bit holes: 1, sum bit holes: 2 bits */ /* member types with bit holes: 1, total: 1 */ /* forced alignments: 1 */ /* last cacheline: 24 bytes */ } __attribute__((__aligned__(8))); Acked-by: Oliver Hartkopp Signed-off-by: Vincent Mailhol Link: https://patch.msgid.link/20250917-can-raw-repack-v2-3-395e8b3a4437@kernel.org Signed-off-by: Marc Kleine-Budde --- net/can/raw.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/can/raw.c b/net/can/raw.c index 5a5ded519cd1..bf65d67b5df0 100644 --- a/net/can/raw.c +++ b/net/can/raw.c @@ -82,10 +82,10 @@ struct uniqframe { struct raw_sock { struct sock sk; - int ifindex; struct net_device *dev; netdevice_tracker dev_tracker; struct list_head notifier; + int ifindex; unsigned int bound:1; unsigned int loopback:1; unsigned int recv_own_msgs:1; @@ -96,10 +96,10 @@ struct raw_sock { canid_t tx_vcid_shifted; canid_t rx_vcid_shifted; canid_t rx_vcid_mask_shifted; + can_err_mask_t err_mask; int count; /* number of active filters */ struct can_filter dfilter; /* default/single filter */ struct can_filter *filter; /* pointer to filter(s) */ - can_err_mask_t err_mask; struct uniqframe __percpu *uniq; }; -- 2.51.0