Messages in this thread | | | From | John Ogness <> | Subject | Re: [PATCH next v3 07/15] printk: introduce CONSOLE_LOG_MAX for improved multi-line support | Date | Tue, 02 Mar 2021 15:34:49 +0100 |
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Hi Geert,
On 2021-03-02, Geert Uytterhoeven <geert@linux-m68k.org> wrote: > On Tue, Mar 2, 2021 at 2:54 PM Geert Uytterhoeven <geert@linux-m68k.org> wrote: >> On Thu, Feb 25, 2021 at 9:30 PM John Ogness <john.ogness@linutronix.de> wrote: >>> Instead of using "LOG_LINE_MAX + PREFIX_MAX" for temporary buffer >>> sizes, introduce CONSOLE_LOG_MAX. This represents the maximum size >>> that is allowed to be printed to the console for a single record. >>> >>> Rather than setting CONSOLE_LOG_MAX to "LOG_LINE_MAX + PREFIX_MAX" >>> (1024), increase it to 4096. With a larger buffer size, multi-line >>> records that are nearly LOG_LINE_MAX in length will have a better >>> chance of being fully printed. (When formatting a record for the >>> console, each line of a multi-line record is prepended with a copy >>> of the prefix.) >>> >>> Signed-off-by: John Ogness <john.ogness@linutronix.de> >>> Reviewed-by: Petr Mladek <pmladek@suse.com> >> >> Thanks for your patch! >> >> This increases kernel size by more than 3 KiB, which affects small >> devices (e.g. SoCs with 10 MiB of SRAM inside).
Petr was concerned that this patch might raise issues for the small devices.
>> Who is printing such long lines to the console?
Some printk users like to print large multi-line messages into a single record. They can get pretty long. But since no one is complaining with the current 1024, we can assume it is big enough.
For v4 I will return it back to 1024 bytes.
> BTW, printing a single line of 1024 characters to a serial console at > 115200 bps takes almost 100 ms.
Yes. Although once we move to threaded printers, I don't think anyone will care. Also, I think the netconsole will become quite attractive when we move to threaded printers.
John Ogness
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