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Lines 893-911
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<programlisting>options ADAPTIVE_GIANT # Giant mutex is adaptive.</programlisting> |
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<programlisting>options ADAPTIVE_GIANT # Giant mutex is adaptive.</programlisting> |
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<para>This option causes Giant to be included in the set of mutexes |
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<para>Giant is the name of a mutual exclusion mechanism (a sleep mutex) |
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adaptively spun on.</para> |
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that protects a large set of kernel resources. Today, this is an |
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unacceptable performance bottleneck which is actively beeing replaced |
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with locks that protect individual resources. The ADAPTIVE_GIANT |
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option causes Giant to be included in the set of mutexes adaptively |
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spun on. That is, when a thread wants to lock the Giant mutex, but it |
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is already locked by a thread on another CPU, the first thread will |
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keep running and wait for the lock to be released. Normally, the |
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thread would instead go back to sleep and wait for its next chance to |
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run.</para> |
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<indexterm> |
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<indexterm> |
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<primary>kernel options</primary> |
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<primary>kernel options</primary> |
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<secondary>SMP</secondary> |
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<secondary>SMP</secondary> |
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</indexterm> |
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</indexterm> |
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<programlisting># To make an SMP kernel, the next two are needed |
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<programlisting>device apic # I/O APIC</programlisting> |
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options SMP # Symmetric MultiProcessor Kernel |
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device apic # I/O APIC</programlisting> |
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<para>The above are both required for SMP support, and can also be |
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<para>The apic device enables the use of I/O APIC for interrupt |
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safely enabled on uniprocessor systems.</para> |
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delivery. The apic device can be used in both UP and SMP kernels, but |
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is required for SMP kernels.</para> |
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<programlisting>device isa</programlisting> |
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<programlisting>device isa</programlisting> |
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Lines 1026-1031
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device asr # DPT SmartRAID V, VI and Adaptec SCSI RAID |
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device asr # DPT SmartRAID V, VI and Adaptec SCSI RAID |
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device ciss # Compaq Smart RAID 5* |
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device ciss # Compaq Smart RAID 5* |
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device dpt # DPT Smartcache III, IV - See NOTES for options |
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device dpt # DPT Smartcache III, IV - See NOTES for options |
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device hptmv # Highpoint RocketRAID 182x |
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device iir # Intel Integrated RAID |
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device iir # Intel Integrated RAID |
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device ips # IBM (Adaptec) ServeRAID |
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device ips # IBM (Adaptec) ServeRAID |
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device mly # Mylex AcceleRAID/eXtremeRAID |
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device mly # Mylex AcceleRAID/eXtremeRAID |