Messages in this thread | | | Date | Fri, 29 May 2015 10:04:43 +0200 | From | "Jan H. Schönherr" <> | Subject | Re: native_cpu_up speed (Re: [PATCH] x86: skip delays during SMP initialization similar to Xen) |
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On 05/29/2015 09:47 AM, Len Brown wrote: > However, a clear pattern jumped out of the trace for how long > the BSP waits for the AP to set itself in cpu_callin_mask. > This is the time in start secondary where cpu_init() is running, > up through smp_callin() is called. > > On the 1st package, each remote AP take 9 delays = 900 us to do this, > whether they are new cores or HT siblings of cores already up. > But the 1st processor on remote_packages_ aka nodes, takes 60,000 us > > No typo -- that is 60ms!
That does sound like calibrate_delay(), which "waits" for 5 * (10ms + 1 tick) on each newly encountered package...
Regards Jan
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