Messages in this thread | | | Date | Mon, 2 Nov 2020 14:40:42 +0100 | From | Petr Mladek <> | Subject | Re: [PATCH v2 1/2] init/Kconfig: Fix CPU number in LOG_CPU_MAX_BUF_SHIFT description |
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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 <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?
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
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