From: Thomas Gleixner <tglx@linutronix.de>
To: Eric Dumazet <edumazet@google.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>,
kernel test robot <oliver.sang@intel.com>,
oe-lkp@lists.linux.dev, lkp@intel.com,
linux-kernel@vger.kernel.org, x86@kernel.org,
Benjamin Segall <bsegall@google.com>,
Frederic Weisbecker <frederic@kernel.org>
Subject: Re: [tip:timers/core] [posix] 1535cb8028: stress-ng.epoll.ops_per_sec 36.2% regression
Date: Thu, 27 Mar 2025 11:50:40 +0100 [thread overview]
Message-ID: <87v7ruycfz.ffs@tglx> (raw)
In-Reply-To: <CANn89i+nAN+p-qRypKxB4ESohXkKVPmHuV_m86j3DPv6_+C=oQ@mail.gmail.com>
On Thu, Mar 27 2025 at 10:11, Eric Dumazet wrote:
> On Thu, Mar 27, 2025 at 9:26 AM Eric Dumazet <edumazet@google.com> wrote:
>
>> We could place all these atomic fields in separate cache lines,
>> to keep read-only fields shared as much as possible.
>>
>
> Following one-liner seems good enough to separate the 4 atomics used
> to control/limit
>
> UCOUNT_RLIMIT_NPROC, UCOUNT_RLIMIT_MSGQUEUE, UCOUNT_RLIMIT_SIGPENDING,
> UCOUNT_RLIMIT_MEMLOCK,
>
>
> diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
> index 7183e5aca282..6cc3fbec3632 100644
> --- a/include/linux/user_namespace.h
> +++ b/include/linux/user_namespace.h
> @@ -120,7 +120,7 @@ struct ucounts {
> kuid_t uid;
> atomic_t count;
> atomic_long_t ucount[UCOUNT_COUNTS];
> - atomic_long_t rlimit[UCOUNT_RLIMIT_COUNTS];
> + atomic_long_t ____cacheline_aligned_in_smp rlimit[UCOUNT_RLIMIT_COUNTS];
> };
Cute. How much bloat does it cause?
next prev parent reply other threads:[~2025-03-27 10:50 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-03-24 6:39 [tip:timers/core] [posix] 1535cb8028: stress-ng.epoll.ops_per_sec 36.2% regression kernel test robot
2025-03-26 8:07 ` Thomas Gleixner
2025-03-26 21:11 ` Mateusz Guzik
2025-03-26 21:43 ` Thomas Gleixner
2025-03-27 6:21 ` Eric Dumazet
2025-03-27 8:10 ` Thomas Gleixner
2025-03-27 8:26 ` Eric Dumazet
2025-03-27 9:11 ` Eric Dumazet
2025-03-27 10:50 ` Thomas Gleixner [this message]
2025-03-27 11:37 ` Eric Dumazet
2025-03-27 13:14 ` Thomas Gleixner
2025-03-27 13:17 ` Eric Dumazet
2025-03-27 13:43 ` Mateusz Guzik
2025-03-27 13:44 ` Eric Dumazet
2025-03-27 13:48 ` Mateusz Guzik
2025-03-27 20:45 ` David Laight
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=87v7ruycfz.ffs@tglx \
--to=tglx@linutronix.de \
--cc=bsegall@google.com \
--cc=edumazet@google.com \
--cc=frederic@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=lkp@intel.com \
--cc=mjguzik@gmail.com \
--cc=oe-lkp@lists.linux.dev \
--cc=oliver.sang@intel.com \
--cc=x86@kernel.org \
/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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox