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1caf8d39c5
struct inet_timewait_death_row uses two cache lines, because we want tw_count to use a full cache line to avoid false sharing. Rework its definition and placement in netns_ipv4 so that: 1) We add 60 bytes of padding after tw_count to avoid false sharing, knowing that tcp_death_row will have ____cacheline_aligned_in_smp attribute. 2) We do not risk padding before tcp_death_row, because we move it at the beginning of netns_ipv4, even if new fields are added later. 3) We do not waste 48 bytes of padding after it. Note that I have not changed dccp. pahole result for struct netns_ipv4 before/after the patch : /* size: 832, cachelines: 13, members: 139 */ /* sum members: 721, holes: 12, sum holes: 95 */ /* padding: 16 */ /* paddings: 2, sum paddings: 55 */ -> /* size: 768, cachelines: 12, members: 139 */ /* sum members: 673, holes: 11, sum holes: 39 */ /* padding: 56 */ /* paddings: 2, sum paddings: 7 */ /* forced alignments: 1 */ Signed-off-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.