On 05/31/2018 12:18 AM, Andy Shevchenko wrote: > On Wed, May 30, 2018 at 12:20 PM, Feng Tang <[email protected]> wrote: >> Currently printk timestamp mostly come from the sched_clock which >> depends on the clock setup, so there are many kernel logs started >> with "[ 0.000000] " before the clock is calibrated. >> >> This patch will provide an debug option for specific platform to >> provide a early boot time clock, so that we can have time info in >> kernel log much earlier, which can show the time info for the early >> kernel boot, and make boottime tuning/optimization easier (boot time >> is critical for phone/tablet and embedded devices). >> >> Capable platform only need to setup the "boot_printk_clock_fn" >> which could return time in nano seconds. >> >> Together with a TSC patch on x86 system, we have easily captured >> some early boottime killer like unwind_init() which takes about >> 300ms in boot phase. > >> +static u64 printk_clock(void) >> +{ >> + /* If platform provides early boot printk clock, then use it */ >> + if (unlikely(system_state == SYSTEM_BOOTING && boot_printk_clock_fn)) >> + return boot_printk_clock_fn(); >> + else >> + return local_clock(); > > 'else' is redundant.
So it is. Is this a style comment? This shouldn't matter to a smart compiler, should it? >> +} thanks, -- ~Randy
