From 8f8b1138fc9f65e3591aac83a4ee394fef34ac1d Mon Sep 17 00:00:00 2001 From: Ashok Raj Date: Thu, 16 Feb 2006 14:01:48 -0800 Subject: [IA64] Count disabled cpus as potential hot-pluggable CPUs Minor updates to earlier patch. - Added to documentation to add ia64 as well. - Minor clarification on how to use disabled cpus - used plain max instead of max_t per Andew Morton. Signed-off-by: Ashok Raj Signed-off-by: Tony Luck --- Documentation/cpu-hotplug.txt | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) (limited to 'Documentation/cpu-hotplug.txt') diff --git a/Documentation/cpu-hotplug.txt b/Documentation/cpu-hotplug.txt index 08c5d04f308..e05278087ff 100644 --- a/Documentation/cpu-hotplug.txt +++ b/Documentation/cpu-hotplug.txt @@ -44,10 +44,20 @@ maxcpus=n Restrict boot time cpus to n. Say if you have 4 cpus, using maxcpus=2 will only boot 2. You can choose to bring the other cpus later online, read FAQ's for more info. -additional_cpus=n [x86_64 only] use this to limit hotpluggable cpus. - This option sets +additional_cpus*=n Use this to limit hotpluggable cpus. This option sets cpu_possible_map = cpu_present_map + additional_cpus +(*) Option valid only for following architectures +- x86_64, ia64 + +ia64 and x86_64 use the number of disabled local apics in ACPI tables MADT +to determine the number of potentially hot-pluggable cpus. The implementation +should only rely on this to count the #of cpus, but *MUST* not rely on the +apicid values in those tables for disabled apics. In the event BIOS doesnt +mark such hot-pluggable cpus as disabled entries, one could use this +parameter "additional_cpus=x" to represent those cpus in the cpu_possible_map. + + CPU maps and such ----------------- [More on cpumaps and primitive to manipulate, please check -- cgit v1.2.3 From 255acee706b333b79f593dd366f16e1f107cccc3 Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Fri, 17 Feb 2006 13:52:46 -0800 Subject: [PATCH] s390: additional_cpus parameter Introduce additional_cpus command line option. By default no additional cpu can be attached to the system anymore. Only the cpus present at IPL time can be switched on/off. If it is desired that additional cpus can be attached to the system the maximum number of additional cpus needs to be specified with this option. This change is necessary in order to limit the waste of per_cpu data structures. Signed-off-by: Heiko Carstens Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/cpu-hotplug.txt | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) (limited to 'Documentation/cpu-hotplug.txt') diff --git a/Documentation/cpu-hotplug.txt b/Documentation/cpu-hotplug.txt index e05278087ff..4d3355da0e2 100644 --- a/Documentation/cpu-hotplug.txt +++ b/Documentation/cpu-hotplug.txt @@ -11,6 +11,8 @@ Joel Schopp ia64/x86_64: Ashok Raj + s390: + Heiko Carstens Authors: Ashok Raj Lots of feedback: Nathan Lynch , @@ -44,11 +46,9 @@ maxcpus=n Restrict boot time cpus to n. Say if you have 4 cpus, using maxcpus=2 will only boot 2. You can choose to bring the other cpus later online, read FAQ's for more info. -additional_cpus*=n Use this to limit hotpluggable cpus. This option sets - cpu_possible_map = cpu_present_map + additional_cpus - -(*) Option valid only for following architectures -- x86_64, ia64 +additional_cpus=n [x86_64, s390 only] use this to limit hotpluggable cpus. + This option sets + cpu_possible_map = cpu_present_map + additional_cpus ia64 and x86_64 use the number of disabled local apics in ACPI tables MADT to determine the number of potentially hot-pluggable cpus. The implementation -- cgit v1.2.3 From 37a3302618a51520e2056494715ea6b4776dd8ab Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Fri, 17 Feb 2006 13:52:47 -0800 Subject: [PATCH] s390: possible_cpus parameter Introduce possible_cpus command line option. Hard sets the number of bits set in cpu_possible_map. Unlike the additional_cpus parameter this one guarantees that num_possible_cpus() will stay constant even if the system gets rebooted and a different number of cpus are present at startup. Signed-off-by: Heiko Carstens Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/cpu-hotplug.txt | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'Documentation/cpu-hotplug.txt') diff --git a/Documentation/cpu-hotplug.txt b/Documentation/cpu-hotplug.txt index 4d3355da0e2..e71bc6cbbc5 100644 --- a/Documentation/cpu-hotplug.txt +++ b/Documentation/cpu-hotplug.txt @@ -58,6 +58,12 @@ mark such hot-pluggable cpus as disabled entries, one could use this parameter "additional_cpus=x" to represent those cpus in the cpu_possible_map. +possible_cpus=n [s390 only] use this to set hotpluggable cpus. + This option sets possible_cpus bits in + cpu_possible_map. Thus keeping the numbers of bits set + constant even if the machine gets rebooted. + This option overrides additional_cpus. + CPU maps and such ----------------- [More on cpumaps and primitive to manipulate, please check -- cgit v1.2.3 From 6303dbf570e410067380daec670fdb4137ac0d1d Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Mon, 20 Feb 2006 18:27:58 -0800 Subject: [PATCH] cpu hotplug documentation fix Looks like there was a merge conflict when patches 8f8b1138fc9f65e3591aac83a4ee394fef34ac1d and 255acee706b333b79f593dd366f16e1f107cccc3 were applied which wasn't properly resolved. Fix this and add some additional description. Signed-off-by: Heiko Carstens Cc: Ashok Raj Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/cpu-hotplug.txt | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) (limited to 'Documentation/cpu-hotplug.txt') diff --git a/Documentation/cpu-hotplug.txt b/Documentation/cpu-hotplug.txt index e71bc6cbbc5..57a09f99ecb 100644 --- a/Documentation/cpu-hotplug.txt +++ b/Documentation/cpu-hotplug.txt @@ -46,10 +46,12 @@ maxcpus=n Restrict boot time cpus to n. Say if you have 4 cpus, using maxcpus=2 will only boot 2. You can choose to bring the other cpus later online, read FAQ's for more info. -additional_cpus=n [x86_64, s390 only] use this to limit hotpluggable cpus. - This option sets +additional_cpus*=n Use this to limit hotpluggable cpus. This option sets cpu_possible_map = cpu_present_map + additional_cpus +(*) Option valid only for following architectures +- x86_64, ia64, s390 + ia64 and x86_64 use the number of disabled local apics in ACPI tables MADT to determine the number of potentially hot-pluggable cpus. The implementation should only rely on this to count the #of cpus, but *MUST* not rely on the @@ -57,6 +59,9 @@ apicid values in those tables for disabled apics. In the event BIOS doesnt mark such hot-pluggable cpus as disabled entries, one could use this parameter "additional_cpus=x" to represent those cpus in the cpu_possible_map. +s390 uses the number of cpus it detects at IPL time to also the number of bits +in cpu_possible_map. If it is desired to add additional cpus at a later time +the number should be specified using this option or the possible_cpus option. possible_cpus=n [s390 only] use this to set hotpluggable cpus. This option sets possible_cpus bits in -- cgit v1.2.3