Date: Tue, 16 Feb 2016 21:33:15 -0800 From: Julian Elischer <julian@freebsd.org> To: John Baldwin <jhb@freebsd.org>, arch@freebsd.org Subject: Re: Starting APs earlier during boot Message-ID: <56C4061B.6010601@freebsd.org> In-Reply-To: <1730061.8Ii36ORVKt@ralph.baldwin.cx> References: <1730061.8Ii36ORVKt@ralph.baldwin.cx>
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On 16/02/2016 12:50 PM, John Baldwin wrote: > Currently the kernel bootstraps the non-boot processors fairly early in the > SI_SUB_CPU SYSINIT. The APs then spin waiting to be "released". We currently > release the APs as one of the last steps at SI_SUB_SMP. On the one hand this > removes much of the need for synchronization while SYSINITs are running since > SYSINITs basically assume they are single-threaded. However, it also enforces > some odd quirks. Several places that deal with per-CPU resources have to > split initialization up so that the BSP init happens in one SYSINIT and the > initialization of the APs happens in a second SYSINIT at SI_SUB_SMP. > > Another issue that is becoming more prominent on x86 (and probably will also [...] what is the goal? cleaner code? faster boot? >
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