Messages in this thread | | | Date | Fri, 11 Jul 2014 12:59:20 +0200 | From | Borislav Petkov <> | Subject | Re: [PATCH] x86,cpu-hotplug: assign same CPU number to readded CPU |
| |
On Fri, Jul 11, 2014 at 09:48:27AM +0900, Yasuaki Ishimatsu wrote: > >>+static int get_cpuid(int apicid)
Btw this "cpuid" is misleading. Call it "cpu_num" or so.
> >>+{ > >>+ int cpuid; > >>+ > >>+ cpuid = apicid_to_cpuid[apicid]; > >>+ if (cpuid < 0) > >>+ cpuid = cpumask_next_zero(-1, cpu_used_mask); > >Why do you need additional cpu bitmask? > > To assing new CPU number, I prepared new cpu bitmask. > > The following two steps are necessary to assign CPU number to APIC ID. > 1. Check whether APIC ID has been assigned CPU number > 2. Assign new CPU number if ACPI ID has not been assigned CPU number (it > means apicid_to_cpuid[] returns -1) > > Step 1. is checked by apicid_to_cpuid[]. And step 2. assigns new CPU > number by using cpu_used_mask. > > To keep cpu number, cpumask must not be cleared by hot removing CPU. > If cpumask is cleared by hot removing CPU, the cpumask cannot be used > to keep CPU number. > > Currently, cpu_present_map is used to assign CPU number. But the cpumask > is cleared by hot removing CPU since the mask is prepared to remember > existed CPUs in the system. So the cpu_present_map must be cleared > at CPU hot remove. > > I confirmed whether present cpumasks (cpu_possible_map, cpu_online_map > et al) is usable or not for this purpose. But there is no cpumask that > can be used to keep CPU number. So I prepared new cpu bitmask. > > >How about just finding the first apicid_to_cpuid[apicid] < 0 > >and dropping not needed anymore bitmask. > > When apicid_to_cpuid[] return -1, kernel assigns new CPU number. For > this, the cpu_used_mask is necessary.
And we can't have that - we cannot have cores which had number X get number Y after hotplug.
Can you send a full dmesg after you've done a physical node hotplug on a machine? Privately is fine too.
Boot with
"ignore_loglevel log_buf_len=10M debug apic=debug show_lapic=all"
please.
Thanks.
-- Regards/Gruss, Boris.
Sent from a fat crate under my desk. Formatting is fine. --
| |