Reducing NR_CPUS from 32 to 2 reduces the kernel footprint by
approximately 240 kilobytes.
Before:
text data bss dec hex filename
2120633 283268 251572 2655473 2884f1 vmlinux
After:
text data bss dec hex filename
2120777 390116 384308 2895201 2c2d61 vmlinux
--- 2.5.20/arch/i386/config.in~config_nr_cpus Thu Jun 6 02:47:35 2002
+++ 2.5.20-akpm/arch/i386/config.in Thu Jun 6 02:47:35 2002
@@ -185,8 +185,8 @@ fi
bool 'Math emulation' CONFIG_MATH_EMULATION
bool 'MTRR (Memory Type Range Register) support' CONFIG_MTRR
-bool 'Symmetric multi-processing support' CONFIG_SMP
bool 'Preemptible Kernel' CONFIG_PREEMPT
+bool 'Symmetric multi-processing support' CONFIG_SMP
if [ "$CONFIG_SMP" != "y" ]; then
bool 'Local APIC support on uniprocessors' CONFIG_X86_UP_APIC
dep_bool 'IO-APIC support on uniprocessors' CONFIG_X86_UP_IOAPIC $CONFIG_X86_UP_APIC
@@ -197,6 +197,7 @@ if [ "$CONFIG_SMP" != "y" ]; then
define_bool CONFIG_X86_IO_APIC y
fi
else
+ int 'Maximum number of CPUs (2-32)' CONFIG_NR_CPUS 32
bool 'Multiquad NUMA system' CONFIG_MULTIQUAD
fi
--- 2.5.20/include/linux/threads.h~config_nr_cpus Thu Jun 6 02:47:35 2002
+++ 2.5.20-akpm/include/linux/threads.h Thu Jun 6 02:47:35 2002
@@ -9,7 +9,13 @@
*/
#ifdef CONFIG_SMP
+
+#ifdef CONFIG_NR_CPUS
+#define NR_CPUS CONFIG_NR_CPUS
+#else
#define NR_CPUS 32 /* Max processors that can be running in SMP */
+#endif
+
#else
#define NR_CPUS 1
#endif
--- 2.5.20/arch/i386/Config.help~config_nr_cpus Thu Jun 6 02:47:35 2002
+++ 2.5.20-akpm/arch/i386/Config.help Thu Jun 6 02:47:35 2002
@@ -25,6 +25,14 @@ CONFIG_SMP
If you don't know what to do here, say N.
+CONFIG_NR_CPUS
+ This allows you to specify the maximum number of CPUs which this
+ kernel will support. The maximum supported value is 32 and the
+ mimimum value which makes sense is 2.
+
+ This is purely to save memory - each supported CPU adds
+ approximately eight kilobytes to the kernel image.
+
CONFIG_PREEMPT
This option reduces the latency of the kernel when reacting to
real-time or interactive events by allowing a low priority process to
--- 2.5.20/arch/i386/kernel/smpboot.c~config_nr_cpus Thu Jun 6 02:53:20 2002
+++ 2.5.20-akpm/arch/i386/kernel/smpboot.c Thu Jun 6 02:57:35 2002
@@ -54,7 +54,7 @@
static int smp_b_stepping;
/* Setup configured maximum number of CPUs to activate */
-static int max_cpus = -1;
+static int max_cpus = NR_CPUS;
/* Total count of live CPUs */
int smp_num_cpus = 1;
@@ -1145,7 +1145,7 @@ void __init smp_boot_cpus(void)
if (!(phys_cpu_present_map & (1 << bit)))
continue;
- if ((max_cpus >= 0) && (max_cpus <= cpucount+1))
+ if (max_cpus <= cpucount+1)
continue;
do_boot_cpu(apicid);
-
-
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This archive was generated by hypermail 2b29 : Fri Jun 07 2002 - 22:00:27 EST