linux-kernel - Re: [PATCH v2 2/3] serial: core: fix sysrq overhead regression

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Message-ID: <8c6d7bae-0ebd-caa7-f9c7-96ec7035abfb@gmail.com>
Date:   Fri, 12 Jun 2020 16:52:06 +0100
From:   Dmitry Safonov <0x7f454c46@...il.com>
To:     Johan Hovold <johan@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Jiri Slaby <jslaby@...e.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/3] serial: core: fix sysrq overhead regression

On 6/10/20 4:22 PM, Johan Hovold wrote:
> Commit 8e20fc391711 ("serial_core: Move sysrq functions from header
> file") converted the inline sysrq helpers to exported functions which
> are now called for every received character, interrupt and break signal
> also on systems without CONFIG_MAGIC_SYSRQ_SERIAL instead of being
> optimised away by the compiler.
> 
> Inlining these helpers again also avoids the function call overhead when
> CONFIG_MAGIC_SYSRQ_SERIAL is enabled (e.g. when the port is not used as
> a console).
> 
> Fixes: 8e20fc391711 ("serial_core: Move sysrq functions from header file")
> Cc: Dmitry Safonov <0x7f454c46@...il.com>
> Signed-off-by: Johan Hovold <johan@...nel.org>

Thanks for sending and the numbers, it's a bit pity that we need to move
them back to the header, but as it matters for your setup,

Reviewed-by: Dmitry Safonov <0x7f454c46@...il.com>

Thanks,
           Dmitry