dd2d660440
napi_id is read by GRO and drivers to mark skbs, and it currently
sits at the end of the structure, in a mostly unused cache line.
Move it up into a hole, and separate the clearly control path
fields from the important ones.
Before:
struct napi_struct {
struct list_head poll_list; /* 0 16 */
long unsigned int state; /* 16 8 */
int weight; /* 24 4 */
int defer_hard_irqs_count; /* 28 4 */
long unsigned int gro_bitmask; /* 32 8 */
int (*poll)(struct napi_struct *, int); /* 40 8 */
int poll_owner; /* 48 4 */
/* XXX 4 bytes hole, try to pack */
struct net_device * dev; /* 56 8 */
/* --- cacheline 1 boundary (64 bytes) --- */
struct gro_list gro_hash[8]; /* 64 192 */
/* --- cacheline 4 boundary (256 bytes) --- */
struct sk_buff * skb; /* 256 8 */
struct list_head rx_list; /* 264 16 */
int rx_count; /* 280 4 */
/* XXX 4 bytes hole, try to pack */
struct hrtimer timer; /* 288 64 */
/* XXX last struct has 4 bytes of padding */
/* --- cacheline 5 boundary (320 bytes) was 32 bytes ago --- */
struct list_head dev_list; /* 352 16 */
struct hlist_node napi_hash_node; /* 368 16 */
/* --- cacheline 6 boundary (384 bytes) --- */
unsigned int napi_id; /* 384 4 */
/* XXX 4 bytes hole, try to pack */
struct task_struct * thread; /* 392 8 */
/* size: 400, cachelines: 7, members: 17 */
/* sum members: 388, holes: 3, sum holes: 12 */
/* paddings: 1, sum paddings: 4 */
/* last cacheline: 16 bytes */
};
After:
struct napi_struct {
struct list_head poll_list; /* 0 16 */
long unsigned int state; /* 16 8 */
int weight; /* 24 4 */
int defer_hard_irqs_count; /* 28 4 */
long unsigned int gro_bitmask; /* 32 8 */
int (*poll)(struct napi_struct *, int); /* 40 8 */
int poll_owner; /* 48 4 */
/* XXX 4 bytes hole, try to pack */
struct net_device * dev; /* 56 8 */
/* --- cacheline 1 boundary (64 bytes) --- */
struct gro_list gro_hash[8]; /* 64 192 */
/* --- cacheline 4 boundary (256 bytes) --- */
struct sk_buff * skb; /* 256 8 */
struct list_head rx_list; /* 264 16 */
int rx_count; /* 280 4 */
unsigned int napi_id; /* 284 4 */
struct hrtimer timer; /* 288 64 */
/* XXX last struct has 4 bytes of padding */
/* --- cacheline 5 boundary (320 bytes) was 32 bytes ago --- */
struct task_struct * thread; /* 352 8 */
struct list_head dev_list; /* 360 16 */
struct hlist_node napi_hash_node; /* 376 16 */
/* size: 392, cachelines: 7, members: 17 */
/* sum members: 388, holes: 1, sum holes: 4 */
/* paddings: 1, sum paddings: 4 */
/* forced alignments: 1 */
/* last cacheline: 8 bytes */
} __attribute__((__aligned__(8)));
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.