Messages in this thread Patch in this message | | | Subject | Re: [PATCH v10 2/7] x86, acpi, cpu-hotplug: Enable acpi to register all possible cpus at boot time. | From | Dou Liyang <> | Date | Tue, 2 Aug 2016 15:30:38 +0800 |
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Hi tglx,
在 2016年07月29日 21:36, Thomas Gleixner 写道: > On Tue, 26 Jul 2016, Dou Liyang wrote: > >> 1. Enable apic registeration flow to handle both enabled and disabled cpus. >> This is done by introducing an extra parameter to generic_processor_info to >> let the caller control if disabled cpus are ignored. > > If I'm reading the patch correctly then the 'enabled' argument controls more > than the disabled cpus accounting. It also controls the modification of > num_processors and the present mask.
In the patch, they both need mapping to a logic cpu. As you said, the 'enabled' controls extra functions:
1. num_processors parameter 2. physid_set method 3. set_cpu_present method
> >> -int generic_processor_info(int apicid, int version) >> +static int __generic_processor_info(int apicid, int version, bool enabled) >> { >> int cpu, max = nr_cpu_ids; >> bool boot_cpu_detected = physid_isset(boot_cpu_physical_apicid, >> @@ -2032,7 +2032,8 @@ int generic_processor_info(int apicid, int version) >> " Processor %d/0x%x ignored.\n", >> thiscpu, apicid); >> >> - disabled_cpus++; >> + if (enabled) >> + disabled_cpus++; >> return -ENODEV; >> } >> >> @@ -2049,7 +2050,8 @@ int generic_processor_info(int apicid, int version) >> " reached. Keeping one slot for boot cpu." >> " Processor %d/0x%x ignored.\n", max, thiscpu, apicid); >> >> - disabled_cpus++; >> + if (enabled) >> + disabled_cpus++; > > This is utterly confusing. That code path cannot be reached when enabled is > false, because num_processors is 0 as we never increment it when enabled is > false. > > That said, I really do not like this 'slap some argument on it and make it > work somehow' approach. > > The proper solution for this is to seperate out the functionality which you > need for the preparation run (enabled = false) and make sure that the > information you need for the real run (enabled = true) is properly cached > somewhere so we don't have to evaluate the same thing over and over.
Thank you very much for your advice. That solution is very good for me.
I thought about the differences between them carefully. Firstly, I intend to separate out the functionality in two functions. It's simple but not good. Then, I try to put them together to judge just once.
After, considering the judgment statement independence and the order of assignment. I remove all the "if (enabled)" code and do the unified judgment like this:
@@ -2180,12 +2176,19 @@ int __generic_processor_info(int apicid, int version, bool enabled) apic->x86_32_early_logical_apicid(cpu); #endif set_cpu_possible(cpu, true); - if (enabled) + + if (enabled){ + num_processors++; + physid_set(apicid, phys_cpu_present_map); set_cpu_present(cpu, true); + }else{ + disabled_cpus++; + }
return cpu; }
I hope that patch could consistent with your advice. And I will submit the detailed modification in the next version patches.
Thanks,
Dou.
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