Re: [PATCH v5 4/7] tcp, flow: Replace per-connection in_epoll flag with an epollid in flow_common

[Stefano Brivio <sbrivio@redhat.com>]

On Tue, 21 Oct 2025 23:01:13 +0200
Laurent Vivier <lvivier@redhat.com> wrote:

> diff --git a/flow.h b/flow.h
> index ef138b83add8..2c58b30ffc6a 100644
> --- a/flow.h
> +++ b/flow.h
> @@ -177,6 +177,7 @@ int flowside_connect(const struct ctx *c, int s,
>   * @type:	Type of packet flow
>   * @pif[]:	Interface for each side of the flow
>   * @side[]:	Information for each side of the flow
> + * @epollid:	epollfd identifier, or EPOLLFD_ID_INVALID
>   */
>  struct flow_common {
>  #ifdef __GNUC__
> @@ -192,8 +193,15 @@ struct flow_common {
>  #endif
>  	uint8_t		pif[SIDES];
>  	struct flowside	side[SIDES];
> +#define EPOLLFD_ID_BITS 8
> +	unsigned int	epollid:EPOLLFD_ID_BITS;
>  };

Just to confirm, on top of Jon's series (adding tap_omac[6] before
this):

struct tcp_tap_conn {
        struct flow_common         f;                    /*     0    84 */
        /* --- cacheline 1 boundary (64 bytes) was 20 bytes ago --- */

	[...]

        /* size: 128, cachelines: 2, members: 19 */
        /* sum members: 115 */
        /* sum bitfield members: 97 bits, bit holes: 1, sum bit holes: 7 bits */
};

...perfect. Tight but we still have 7 bits (in a single chunk) should
we ever need something else.

-- 
Stefano