On Fri 2020-10-30 17:00:18, Paul Menzel wrote:
> Dear Petr,
>
>
> Am 11.08.20 um 11:29 schrieb Paul Menzel:
> > Currently, LOG_BUF_SHIFT defaults to 17, which is 2 ^ 17 bytes = 128 KB,
> > and LOG_CPU_MAX_BUF_SHIFT defaults to 12, which is 2 ^ 12 bytes = 4 KB.
> >
> > Half of 128 KB is 64 KB, so more than 16 CPUs are required for the value
> > to be used, as then the sum of contributions is greater than 64 KB for
> > the first time. My guess is, that the description was written with the
> > configuration values used in the SUSE in mind.
> >
> > Fixes: 23b2899f7f ("printk: allow increasing the ring buffer depending on
> > the number of CPUs")
> > Cc: Luis R. Rodriguez <[email protected]>
> > Cc: [email protected]
> > Reviewed-by: Petr Mladek <[email protected]>
> > Signed-off-by: Paul Menzel <[email protected]>
> > ---
> > v2: Add Reviewed-by tag
> >
> > init/Kconfig | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/init/Kconfig b/init/Kconfig
> > index d6a0b31b13dc..9dc607e3806f 100644
> > --- a/init/Kconfig
> > +++ b/init/Kconfig
> > @@ -718,7 +718,7 @@ config LOG_CPU_MAX_BUF_SHIFT
> > with more CPUs. Therefore this value is used only when the sum of
> > contributions is greater than the half of the default kernel ring
> > buffer as defined by LOG_BUF_SHIFT. The default values are set
> > - so that more than 64 CPUs are needed to trigger the allocation.
> > + so that more than 16 CPUs are needed to trigger the allocation.
> > Also this option is ignored when "log_buf_len" kernel parameter is
> > used as it forces an exact (power of two) size of the ring buffer.
>
> Could you please apply this trivial patch from the two patches already, so I
> do not have to resend it?
The patch is committed in printk/linux.git, branch for-5.10-trivial.
I am not going to create pull request just for this trivial fix.
I will push it for-5.10 only together with eventual more urgent fix.
It is very likely that it will have to wait for 5.11.
Best Regards,
Petr
