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 <mcg...@suse.com> Cc: linux-kernel@vger.kernel.org Reviewed-by: Petr Mladek <pmla...@suse.com> Signed-off-by: Paul Menzel <pmen...@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 isused 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
