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c3426ba2ed
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>
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 reStructuredText 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.