linux-kernel - Re: [PATCH v2] kernel/params.c: defer most of param_sysfs_init() to late

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Message-ID: <Y1hsA1b3GwJuxxE/@bombadil.infradead.org>
Date:   Tue, 25 Oct 2022 16:06:43 -0700
From:   Luis Chamberlain <mcgrof@...nel.org>
To:     Rasmus Villemoes <linux@...musvillemoes.dk>
Cc:     Miroslav Benes <mbenes@...e.cz>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] kernel/params.c: defer most of param_sysfs_init() to
 late_initcall time

On Wed, Oct 26, 2022 at 12:13:56AM +0200, Rasmus Villemoes wrote:
> param_sysfs_init(), and in particular param_sysfs_builtin() is rather
> time-consuming; for my board, it currently takes about 30ms.
> 
> That amounts to about 3% of the time budget I have from U-Boot hands
> over control to linux and linux must assume responsibility for keeping
> the external watchdog happy.
> 
> We must still continue to initialize module_kset at subsys_initcall
> time, since otherwise any request_module() would fail in
> mod_sysfs_init(). However, the bulk of the work in
> param_sysfs_builtin(), namely populating /sys/module/*/version and/or
> /sys/module/*/parameters/ for builtin modules, can be deferred to
> late_initcall time - there's no userspace yet anyway to observe
> contents of /sys or the lack thereof.
> 
> Signed-off-by: Rasmus Villemoes <linux@...musvillemoes.dk>

Thanks, queued onto modules-next.

  Luis