From: Jakub Kicinski <kuba@kernel.org>
To: Eric Dumazet <edumazet@google.com>
Cc: "David S . Miller" <davem@davemloft.net>,
Paolo Abeni <pabeni@redhat.com>, Simon Horman <horms@kernel.org>,
Neal Cardwell <ncardwell@google.com>,
Kuniyuki Iwashima <kuniyu@google.com>,
Willem de Bruijn <willemb@google.com>,
netdev@vger.kernel.org, eric.dumazet@gmail.com
Subject: Re: [PATCH v2 net-next 0/9] tcp: avoid struct socket cache line miss in tcp_check_space()
Date: Mon, 28 Sep 2026 18:18:54 -0700 [thread overview]
Message-ID: <20260928181854.0b520fcf@kernel.org> (raw)
In-Reply-To: <20260924134729.2047213-1-edumazet@google.com>
On Thu, 24 Sep 2026 13:47:20 +0000 Eric Dumazet wrote:
> tcp_check_space() is called on every incoming ACK and every transmitted
> packet, and tests SOCK_NOSPACE in sk->sk_socket->flags. Because struct
> socket lives in its own cache line and the TCP fast paths do not touch
> it for anything else, that test pulls in an extra cache line that is
> cold when the working set of active sockets is large.
>
> This series mirrors SOCK_NOSPACE into a new u8 field, tp->tcp_nospace,
> placed right after tp->chrono_type in the tcp_sock_write_tx cache line
> group (fitting in an existing 3-byte hole before chrono_start, so no
> other field moves and sizeof(struct tcp_sock) is unchanged). Both the
> transmit and ACK fast paths already touch that cache line, making the
> fast-path test in tcp_check_space() free of extra cache misses while
> keeping __tcp_check_space() authoritative on SOCK_NOSPACE.
Please resend this and CC the maintainers of the code we're about
to change.
--
pw-bot: cr
prev parent reply other threads:[~2026-09-29 1:18 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-24 13:47 [PATCH v2 net-next 0/9] tcp: avoid struct socket cache line miss in tcp_check_space() Eric Dumazet
2026-09-24 13:47 ` [PATCH v2 net-next 1/9] dlm: fix send buffer backpressure handling Eric Dumazet
2026-09-25 13:49 ` netdev-bot+sashiko
2026-09-24 13:47 ` [PATCH v2 net-next 2/9] net: add sk_set_nospace() and sk_clear_nospace() Eric Dumazet
2026-09-25 13:49 ` netdev-bot+sashiko
2026-09-24 13:47 ` [PATCH v2 net-next 3/9] sunrpc: use " Eric Dumazet
2026-09-24 13:47 ` [PATCH v2 net-next 4/9] rds: use sk_set_nospace() Eric Dumazet
2026-09-24 13:47 ` [PATCH v2 net-next 5/9] dlm: use sk_set_nospace() and sk_clear_nospace() Eric Dumazet
2026-09-24 13:47 ` [PATCH v2 net-next 6/9] drbd: use sk_set_nospace() Eric Dumazet
2026-09-24 13:47 ` [PATCH v2 net-next 7/9] nvme-tcp: use sk_clear_nospace() Eric Dumazet
2026-09-24 13:47 ` [PATCH v2 net-next 8/9] libceph: " Eric Dumazet
2026-09-24 13:47 ` [PATCH v2 net-next 9/9] tcp: add tp->tcp_nospace Eric Dumazet
2026-09-29 1:18 ` Jakub Kicinski [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20260928181854.0b520fcf@kernel.org \
--to=kuba@kernel.org \
--cc=davem@davemloft.net \
--cc=edumazet@google.com \
--cc=eric.dumazet@gmail.com \
--cc=horms@kernel.org \
--cc=kuniyu@google.com \
--cc=ncardwell@google.com \
--cc=netdev@vger.kernel.org \
--cc=pabeni@redhat.com \
--cc=willemb@google.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.