Messages in this thread | | | Subject | Re: [PATCH v2 1/2] init/Kconfig: Fix CPU number in LOG_CPU_MAX_BUF_SHIFT description | From | Paul Menzel <> | Date | Fri, 30 Oct 2020 17:00:18 +0100 |
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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 <mcgrof@suse.com> > Cc: linux-kernel@vger.kernel.org > Reviewed-by: Petr Mladek <pmladek@suse.com> > Signed-off-by: Paul Menzel <pmenzel@molgen.mpg.de> > --- > 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?
Kind regards,
Paul
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