[PATCH 38/38] x86: use num_processors for possible cpus

Yinghai Lu
2010-01-22T09:26:19Z

some systems that have disable cpus entries because same
BIOS will support 2 sockets and 4 sockets and more at
same time, BIOS just leave some disable entries, but
those system do not support cpu hotplug. we don't need
treat disabled_cpus as hotplug cpus.
so we can make nr_cpu_ids smaller and save more space
(pcpu data allocations), and could make some systems run
with logical flat instead of physical flat apic mode

-v2: change to black list instead
-v3: just remove that, and the one use possible_cpus= directly.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
---
arch/x86/kernel/smpboot.c | 3 +--
1 files changed, 1 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index f741c33..642440c 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1190,7 +1190,6 @@ early_param("possible_cpus", _setup_possible_cpus);
* - Ashok Raj
*
* Three ways to find out the number of additional hotplug CPUs:
- * - If the BIOS specified disabled CPUs in ACPI/mptables use that.
* - The user can overwrite it with possible_cpus=NUM
* - Otherwise don't reserve additional CPUs.
* We do this because additional CPUs waste a lot of memory.
@@ -1205,7 +1204,7 @@ __init void prefill_possible_map(void)
num_processors = 1;

if (setup_possible_cpus == -1)
- possible = num_processors + disabled_cpus;
+ possible = num_processors;
else
possible = setup_possible_cpus;

--
1.6.4.2