Messages in this thread | | | From | Kay Sievers <> | Date | Fri, 3 Aug 2012 11:48:26 +0200 | Subject | Re: [PATCH v2] printk: add option to print cpu id |
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On Fri, Aug 3, 2012 at 11:36 AM, Pandita, Vikram <vikram.pandita@ti.com> wrote: > On Fri, Aug 3, 2012 at 2:32 AM, Venu Byravarasu <vbyravarasu@nvidia.com> wrote:
>> As having Macro locally in the file of interest would serve the purpose, >> Why to change the printk code? > > As stated, the logic followed is exactly similar to well proven and > approved way to handle printk time stamp: CONFIG_PRINTK_TIME > Its an overhead on the system that enables the config option: > CONFIG_PRINTK_CPUID > Otherwise the system remains as is. > > To gain insight on SMP system logging behavior, the price to pay is > the extra 4 chars per printk line, > just like printk-time adds 15 chars to each line. Both options can be > disabled as desired. > > So i am not sure what kind of option you are proposing? > Do u imply PRINTK_TIME is not right then?
It's 8 bytes per message for storing the timestamp in the records. There is never 15 bytes storage space needed, the prefix is constructed on-the-fly only while exporting the data.
The CPU-ID would need at least two additional bytes (2^16 CPUS) in every record, unless it's a compile-time option. I can't tell, if everybody wants to pay the storage space for the the CPU-ID feature.
Kay
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