On Fri, Aug 3, 2012 at 10:54 AM, Andi Kleen <andi@xxxxxxxxxxxxxx> wrote: > Vikram Pandita <vikram.pandita@xxxxxx> writes: > >> From: Vikram Pandita <vikram.pandita@xxxxxx> >> >> Introduce config option to enable CPU id reporting for printk() calls. > > What's wrong with using trace_printk for this? trace_printk works only when you know the _exact_ path in code that you want to profile. When you have no idea of a random lockup, then it would be kind of touch and time consuming to put trace prints all around the code. > That's much faster > anyways. Generally printk is so slow that it's typically useless for > instrumenting races. > As stated in another thread, its found useful to debug some specific cases: Check thread: http://marc.info/?l=linux-omap&m=134401269106619&w=2 > And really: Wasting 1/3 of the 80 character line is too much. You _WASTE_ 4 chars only if you are interested in this info by enabling: CONFIG_PRINTK_CPUID Just like you _WASTE_ 15 chars when you enable existing: CONFIG_PRINTK_TIME For general usecase, recommendation would be to keep these options disabled. Working on shipping products, i find almost all shipping with CONFIG_PRINTK_TIME enabled, so there must be some value. Same would hold for the use case being debugged for CPUID enabling. > > -Andi > > -- > ak@xxxxxxxxxxxxxxx -- Speaking for myself only -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
