Messages in this thread | | | From | Andy Shevchenko <> | Date | Wed, 30 May 2018 16:25:07 +0300 | Subject | Re: [RFC 2/2] x86, tsc: Enable clock for ealry printk timestamp |
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On Wed, May 30, 2018 at 12:20 PM, Feng Tang <feng.tang@intel.com> wrote: > To show time info in kernel log earlier and help optimizing kernel > boot time, printk adds a debug hook "boot_printk_clock_fn()" for > capable platform which has accurate clock in early boot phase. > > This patch will add early param setup option, so that user can > chose to provide a tsc based early printk clock simply by adding > in command line: "boot_tsc=xxxxM" (xxxxM is the stable TSC freq).
> +
This line is not needed.
> + cur_tsc = rdtsc(); > + cur_tsc -= boot_tsc_offset;
In one expression?
> + if (!p) > + return -EINVAL; > +
I'm not sure it's needed at all.
> + boot_tsc_mhz = div64_u64(tsc_hz, 1024 * 1024);
Hmm... 1024*1024 != 1000 * 1000. So, hz -> mhz here (as by suffixes) looks weird.
> + if (boot_tsc_mhz == 0) > + return -EINVAL;
> + pr_info("TSC has run for %lld us\n", > + div64_u64(boot_tsc_offset, boot_tsc_mhz)); > + > + /* Setup the early printk clock */ > + boot_printk_clock_fn = boot_tsc_clock;
> + pr_info("TSC: Setup early printk timestamp with %lldM TSC.", > + boot_tsc_mhz);
Perhaps remove period (above doesn't have it) and move this to one line?
-- With Best Regards, Andy Shevchenko
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