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References: <20241102100839.2325651-1-david.marchand@redhat.com>
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In-Reply-To: <20241102113232.2333703-1-david.marchand@redhat.com>
From: Luca Boccassi <luca.boccassi@gmail.com>
Date: Sat, 2 Nov 2024 12:36:56 +0000
Message-ID: <CAMw=ZnQ9FxWAFA-YUbc8KcyJ-vev_4OsS8WcLvYgpY1KMULK=A@mail.gmail.com>
Subject: Re: [PATCH v2] eal/unix: optimize thread creation with glibc
To: David Marchand <david.marchand@redhat.com>
Cc: dev@dpdk.org, thomas@monjalon.net, stephen@networkplumber.org,
stable@dpdk.org, Tyler Retzlaff <roretzla@linux.microsoft.com>
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On Sat, 2 Nov 2024 at 11:32, David Marchand <david.marchand@redhat.com> wrote:
>
> Setting the cpu affinity of the child thread from the parent thread is
> racy when using pthread_setaffinity_np, as the child thread may start
> running and initialize before affinity is set.
>
> On the other hand, setting the cpu affinity from the child thread itself
> may fail, so the parent thread waits for the child thread to report
> whether this call succeeded.
>
> This synchronisation point resulted in a significant slow down of
> rte_thread_create() (as seen in the lcores_autotest unit tests, in OBS
> for some ARM systems).
>
> Another option for setting cpu affinity is to use the not portable
> pthread_attr_setaffinity_np, but it is not available with musl.
> Assume availability by relying on __USE_GNU that is set with glibc.
>
> Fixes: b28c6196b132 ("eal/unix: fix thread creation")
> Cc: stable@dpdk.org
>
> Signed-off-by: David Marchand <david.marchand@redhat.com>
> ---
> Changes since v1:
> - fixed build with FreeBSD,
>
> ---
> lib/eal/unix/rte_thread.c | 25 +++++++++++++++++++++++++
> 1 file changed, 25 insertions(+)
The test now completes in 1.19 seconds, so this fixes the issue with glibc:
[ 438s] 36/82 DPDK:fast-tests / lcores_autotest OK
1.19s
I do not use musl, so this is good enough for me. Thanks!
Acked-by: Luca Boccassi <bluca@debian.org>