2005-01-07 00:58:16

by YhLu

Subject: RE: 256 apic id for amd64

Andi,

I made the Opteron using apic id from 16 later in LinuxBIOS.

So leave 0-15 for ioapic.

The problem is that the kernel (caliberate_delay) doesn't like that.

If using lpj=2170880 as the command line for that, it works well.

What's the jiffies? The TSC is changing but it doesn't.

YH

Without offset:
Dentry cache hash table entries: 262144 (order: 9, 2097152 bytes)
Inode-cache hash table entries: 131072 (order: 8, 1048576 bytes)
Memory: 1019456k/1048576k available (3011k kernel code, 0k reserved, 1310k
data, 544k init)
LYH calibrating 0 jiffies = 4294667563, now=2922366256
LYH calibrating 1 jiffies = 4294667568, now=2934372713
LYH calibrating 3 jiffies = 4294667600, now=3003581909
4341.76 BogoMIPS (lpj=2170880)
Mount-cache hash table entries: 256 (order: 0, 4096 bytes)
CPU: L1 I Cache: 64K (64 bytes/line), D cache 64K (64 bytes/line)
CPU: L2 Cache: 1024K (64 bytes/line)
CPU 0 -> Node 0
CPU: Physical Processor ID: 0

With apic id offset:
Console: colour dummy device 80x25
Dentry cache hash table entries: 262144 (order: 9, 2097152 bytes)
Inode-cache hash table entries: 131072 (order: 8, 1048576 bytes)
Memory: 1019456k/1048576k available (3011k kernel code, 0k reserved, 1310k
data, 544k init)
LYH calibrating 0 jiffies = 4294667296, now=1383947209
LYH calibrating 1 jiffies = 4294667296, now=1395952717


Please refer the print in init/main.c

void __devinit calibrate_delay(void)
{
unsigned long ticks, loopbit;
int lps_precision = LPS_PREC;
+ unsigned long now;
+
+ rdtscl(now);
+
+ printk("LYH calibrating 0 jiffies = %lu, now=%lu\r\n", jiffies,
now);


if (preset_lpj) {
loops_per_jiffy = preset_lpj;
printk("Calibrating delay loop (skipped)... "
"%lu.%02lu BogoMIPS preset\n",
loops_per_jiffy/(500000/HZ),
(loops_per_jiffy/(5000/HZ)) % 100);
} else {
loops_per_jiffy = (1<<12);

+ rdtscl(now);
+ printk("LYH calibrating 1 jiffies = %lu, now=%lu\r\n",
jiffies, now);
printk(KERN_DEBUG "Calibrating delay loop... ");
while ((loops_per_jiffy <<= 1) != 0) {
/* wait for "start of" clock tick */
ticks = jiffies;
while (ticks == jiffies)
/* nothing */;
/* Go .. */
ticks = jiffies;
__delay(loops_per_jiffy);
ticks = jiffies - ticks;
if (ticks)
break;
}

/*
* Do a binary approximation to get loops_per_jiffy set to
* equal one clock (up to lps_precision bits)
*/
+ rdtscl(now);
+ printk("LYH calibrating 2 jiffies = %lu, now=%lu\r\n",
jiffies, now);

loops_per_jiffy >>= 1;
loopbit = loops_per_jiffy;
while (lps_precision-- && (loopbit >>= 1)) {
loops_per_jiffy |= loopbit;
ticks = jiffies;
while (ticks == jiffies)
/* nothing */;
ticks = jiffies;
__delay(loops_per_jiffy);
if (jiffies != ticks) /* longer than 1 tick */
loops_per_jiffy &= ~loopbit;
}

+ rdtscl(now);
+ printk("LYH calibrating 3 jiffies = %lu, now=%lu\r\n",
jiffies, now);

/* Round the value and print it */
printk("%lu.%02lu BogoMIPS (lpj=%lu)\n",
loops_per_jiffy/(500000/HZ),
(loops_per_jiffy/(5000/HZ)) % 100,
loops_per_jiffy);
}

}

2005-01-07 12:44:55

by Andi Kleen

Subject: Re: 256 apic id for amd64

On Thu, Jan 06, 2005 at 05:06:35PM -0800, YhLu wrote:
> Andi,
>
> I made the Opteron using apic id from 16 later in LinuxBIOS.
>
> So leave 0-15 for ioapic.
>
> The problem is that the kernel (caliberate_delay) doesn't like that.
>
> If using lpj=2170880 as the command line for that, it works well.
>
> What's the jiffies? The TSC is changing but it doesn't.

jiffies is a counter of the timer interrupt. Most likely you broke
the timer somehow.

-Andi