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authorAlok Kataria <akataria@vmware.com>2008-06-20 15:06:33 -0700
committerIngo Molnar <mingo@elte.hu>2008-06-23 22:51:33 +0200
commit3da757daf86e498872855f0b5e101f763ba79499 (patch)
treebffffafed7322c66a1b886b661cfd8a8a7f5a924 /arch
parente01b70ef3eb3080fecc35e15f68cd274c0a48163 (diff)
x86: use cpu_khz for loops_per_jiffy calculation
On the x86 platform we can use the value of tsc_khz computed during tsc calibration to calculate the loops_per_jiffy value. Its very important to keep the error in lpj values to minimum as any error in that may result in kernel panic in check_timer. In virtualization environment, On a highly overloaded host the guest delay calibration may sometimes result in errors beyond the ~50% that timer_irq_works can handle, resulting in the guest panicking. Does some formating changes to lpj_setup code to now have a single printk to print the bogomips value. We do this only for the boot processor because the AP's can have different base frequencies or the BIOS might boot a AP at a different frequency. Signed-off-by: Alok N Kataria <akataria@vmware.com> Cc: Arjan van de Ven <arjan@infradead.org> Cc: Daniel Hecht <dhecht@vmware.com> Cc: Tim Mann <mann@vmware.com> Cc: Zach Amsden <zach@vmware.com> Cc: Sahil Rihan <srihan@vmware.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kernel/time_64.c2
-rw-r--r--arch/x86/kernel/tsc_32.c5
2 files changed, 7 insertions, 0 deletions
diff --git a/arch/x86/kernel/time_64.c b/arch/x86/kernel/time_64.c
index c737849e2ef7..12b4a71bd074 100644
--- a/arch/x86/kernel/time_64.c
+++ b/arch/x86/kernel/time_64.c
@@ -123,6 +123,8 @@ void __init time_init(void)
(boot_cpu_data.x86_vendor == X86_VENDOR_AMD))
cpu_khz = calculate_cpu_khz();
+ lpj_tsc = ((unsigned long)tsc_khz * 1000)/HZ;
+
if (unsynchronized_tsc())
mark_tsc_unstable("TSCs unsynchronized");
diff --git a/arch/x86/kernel/tsc_32.c b/arch/x86/kernel/tsc_32.c
index 068759db63dd..be729035b30b 100644
--- a/arch/x86/kernel/tsc_32.c
+++ b/arch/x86/kernel/tsc_32.c
@@ -401,6 +401,7 @@ static inline void check_geode_tsc_reliable(void) { }
void __init tsc_init(void)
{
int cpu;
+ u64 lpj;
if (!cpu_has_tsc || tsc_disabled) {
/* Disable the TSC in case of !cpu_has_tsc */
@@ -421,6 +422,10 @@ void __init tsc_init(void)
return;
}
+ lpj = ((u64)tsc_khz * 1000);
+ do_div(lpj, HZ);
+ lpj_tsc = lpj;
+
printk("Detected %lu.%03lu MHz processor.\n",
(unsigned long)cpu_khz / 1000,
(unsigned long)cpu_khz % 1000);