Patchwork faster AP launch for recent AMD processors

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Submitter Scott
Date 2010-10-18 20:24:11
Message ID <35B52E279BF8432189BEEB5D66BCA31F@m3a78>
Download mbox | patch
Permalink /patch/2141/
State Accepted
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Comments

Scott - 2010-10-18 20:24:11
]
]> To reduce boot time, removing the double startup IPI and 10 ms
]> delay from lapic_cpu_init.c should be considered. Because I can
]> test this code only on recent AMD cpu models, it is only safe
]> to apply the change in those cases. The following patch uses
]> a compile time check to identify CPUs where the change is known
]> to work. Would a runtime check be better?
]Until Fam10 and K8 can use the same image, compile time is probably the
]correct way to do it.  If there ends up being a long list of processors that
]don't need the wait, we could add a Kconfig option like
]CONFIG_NO_LAPIC_DELAY.
]
]> Signed-off-by: Scott Duplichan <scott@notabs.org>
]Acked-by: Myles Watson <mylesgw@gmail.com>
]
]> +   #if !defined (CONFIG_CPU_AMD_MODEL_10XXX) && !defined
]> (CONFIG_CPU_AMD_MODEL_14XXX)
]>         mdelay(10);
]> +   #endif
]> 
]>         printk(BIOS_SPEW, "Deasserting INIT.\n");
]> 
]> @@ -144,6 +146,9 @@
]>  #endif
]> 
]>         num_starts = 2;
]> +   #if defined (CONFIG_CPU_AMD_MODEL_10XXX) || defined
]> (CONFIG_CPU_AMD_MODEL_14XXX)
]> +       num_starts = 1;
]> +       #endif
]
]I'd prefer it if they both used the same logic.  I think it will make it
]easier to update in the future.  Maybe something like this:
]
]#if !defined (CONFIG_CPU_AMD_MODEL_10XXX) && !defined
](CONFIG_CPU_AMD_MODEL_14XXX)
]	num_starts = 2;
]#else
]	num_starts = 1;
]#endif
]
]Thanks,
]Myles
]


Hello Myles,

Thanks. Of course you are right, consistent logic is best...
I also tried to make the indentation match the surrounding code.


Signed-off-by: Scott Duplichan <scott@notabs.org>
Myles Watson - 2010-10-18 21:17:40
On Mon, Oct 18, 2010 at 2:24 PM, Scott Duplichan <scott@notabs.org> wrote:
> ]
> ]> To reduce boot time, removing the double startup IPI and 10 ms
> ]> delay from lapic_cpu_init.c should be considered. Because I can
> ]> test this code only on recent AMD cpu models, it is only safe
> ]> to apply the change in those cases. The following patch uses
> ]> a compile time check to identify CPUs where the change is known
> ]> to work.

> Signed-off-by: Scott Duplichan <scott@notabs.org>
Acked-by: Myles Watson <mylesgw@gmail.com>

Thanks,
Myles

Patch

Index: src/cpu/x86/lapic/lapic_cpu_init.c
===================================================================
--- src/cpu/x86/lapic/lapic_cpu_init.c  (revision 5965)
+++ src/cpu/x86/lapic/lapic_cpu_init.c  (working copy)
@@ -113,7 +113,9 @@ 
                }
                return 0;
        }
+#if !defined (CONFIG_CPU_AMD_MODEL_10XXX) && !defined (CONFIG_CPU_AMD_MODEL_14XXX)
        mdelay(10);
+#endif

        printk(BIOS_SPEW, "Deasserting INIT.\n");

@@ -143,7 +145,11 @@ 
        start_eip = (unsigned long)_secondary_start;
 #endif

+#if !defined (CONFIG_CPU_AMD_MODEL_10XXX) && !defined (CONFIG_CPU_AMD_MODEL_14XXX)
        num_starts = 2;
+#else
+       num_starts = 1;
+#endif

        /*
         * Run STARTUP IPI loop.