Commit 33a3bd6e authored by Ingo Molnar's avatar Ingo Molnar Committed by Linus Torvalds

[PATCH] ia32: tsc synchronisation cleanup

Clean up the TSC-synchronization code: get rid of div64 and calm down the
printks.
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 34878c84
......@@ -191,34 +191,6 @@ static unsigned long long tsc_values[NR_CPUS];
#define NR_LOOPS 5
/*
* accurate 64-bit/32-bit division, expanded to 32-bit divisions and 64-bit
* multiplication. Not terribly optimized but we need it at boot time only
* anyway.
*
* result == a / b
* == (a1 + a2*(2^32)) / b
* == a1/b + a2*(2^32/b)
* == a1/b + a2*((2^32-1)/b) + a2/b + (a2*((2^32-1) % b))/b
* ^---- (this multiplication can overflow)
*/
static unsigned long long __init div64 (unsigned long long a, unsigned long b0)
{
unsigned int a1, a2;
unsigned long long res;
a1 = ((unsigned int*)&a)[0];
a2 = ((unsigned int*)&a)[1];
res = a1/b0 +
(unsigned long long)a2 * (unsigned long long)(0xffffffff/b0) +
a2 / b0 +
(a2 * (0xffffffff % b0)) / b0;
return res;
}
static void __init synchronize_tsc_bp (void)
{
int i;
......@@ -228,7 +200,7 @@ static void __init synchronize_tsc_bp (void)
unsigned long one_usec;
int buggy = 0;
printk("checking TSC synchronization across %u CPUs: ", num_booting_cpus());
printk(KERN_INFO "checking TSC synchronization across %u CPUs: ", num_booting_cpus());
/* convert from kcyc/sec to cyc/usec */
one_usec = cpu_khz / 1000;
......@@ -283,7 +255,8 @@ static void __init synchronize_tsc_bp (void)
sum += t0;
}
}
avg = div64(sum, num_booting_cpus());
avg = sum;
do_div(avg, num_booting_cpus());
sum = 0;
for (i = 0; i < NR_CPUS; i++) {
......@@ -301,18 +274,18 @@ static void __init synchronize_tsc_bp (void)
buggy = 1;
printk("\n");
}
realdelta = div64(delta, one_usec);
realdelta = delta;
do_div(realdelta, one_usec);
if (tsc_values[i] < avg)
realdelta = -realdelta;
printk("BIOS BUG: CPU#%d improperly initialized, has %ld usecs TSC skew! FIXED.\n", i, realdelta);
printk(KERN_INFO "CPU#%d had %ld usecs TSC skew, fixed it up.\n", i, realdelta);
}
sum += delta;
}
if (!buggy)
printk("passed.\n");
;
}
static void __init synchronize_tsc_ap (void)
......
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