diff options
| author | Alok Kataria <akataria@vmware.com> | 2008-06-20 15:06:33 -0700 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2008-06-23 22:51:33 +0200 |
| commit | 3da757daf86e498872855f0b5e101f763ba79499 (patch) | |
| tree | bffffafed7322c66a1b886b661cfd8a8a7f5a924 /arch | |
| parent | e01b70ef3eb3080fecc35e15f68cd274c0a48163 (diff) | |
| download | linux-3da757daf86e498872855f0b5e101f763ba79499.tar.bz2 | |
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.c | 2 | ||||
| -rw-r--r-- | arch/x86/kernel/tsc_32.c | 5 |
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); |