Please find attach a fix to the TSC (Time Stamp Counter) based
bogoMIPS calculation used on secondary CPUs which has two faults:
1. Not handling wrapping of the lower 32 bits of the TSC counter
on 32bit kernel - perhaps TSC is not reset by a warm reset?
2. TSC and Jiffies are no incrementing together properly. Either
jiffies increment too quickly or Time Stamp Counter isn't incremented
in during an SMI but the real time clock is and jiffies are incremented.
Case 1 can result in a factor of 16 too large a value which makes
udelay() values too small and can cause mysterious driver errors.
Case 2 appears to give smaller 10-15% errors after averaging but
enough to cause occasional failures on my own board
I have tested this code on my own branch and attach patch suitable for
current kernel code. See below for examples of the failures and
how the fix handles these situations now.
I reported this issue earlier here:
Intermittent problem with BogoMIPs calculation on Intel AP CPUs -
http://marc.info/?l=linux-kernel&m=129947246316875&w=4
I suspect this issue has been seen by others but as it is intermittent
and bogoMIPS for secondary CPUs are no longer printed out it might
have been difficult to identify this as the cause. Perhaps these
unresolved issues, although quite old, might be relevant as possibly
this fault has been around for a while. In particular Case 1 may only
be relevant to 32bit kernels on newer HW (most people run 64bit
kernels?). Case 2 is less dramatic since the earlier fix in this area
and also intermittent.
Re: bogomips discrepancy on Intel Core2 Quad CPU -
http://marc.info/?l=linux-kernel&m=118929277524298&w=4
slow system and bogus bogomips -
http://marc.info/?l=linux-kernel&m=116791286716107&w=4
Re: Re: [RFC-PATCH] clocksource: update lpj if clocksource has -
http://marc.info/?l=linux-kernel&m=128952775819467&w=4
This issue is masked a little by commit
feae3203d711db0a9965300ee6d592257fdaae4f which only prints out the
first bogoMIPS value making it
much harder to notice other values differing. Perhaps it should be
changed to only suppress them when they are similar values?
Here are some outputs showing faults occurring and the new code
handling them properly. See my earlier message for examples of the
original failure.
Case 1: A Time Stamp Counter wrap:
...
Calibrating delay loop (skipped), value calculated using timer
frequency.. 6332.70 BogoMIPS (lpj=31663540)
....
calibrate_delay_direct() timer_rate_max=31666493
timer_rate_min=31666151 pre_start=4170369255 pre_end=4202035539
calibrate_delay_direct() timer_rate_max=2425955274
timer_rate_min=2425954941 pre_start=4265368533 pre_end=2396356387
calibrate_delay_direct() ignoring timer_rate as we had a TSC wrap
around start=4265368581 >=post_end=2396356511
calibrate_delay_direct() timer_rate_max=31666274
timer_rate_min=31665942 pre_start=2440373374 pre_end=2472039515
calibrate_delay_direct() timer_rate_max=31666492
timer_rate_min=31666160 pre_start=2535372139 pre_end=2567038422
calibrate_delay_direct() timer_rate_max=31666455
timer_rate_min=31666207 pre_start=2630371084 pre_end=2662037415
Calibrating delay using timer specific routine.. 6333.28 BogoMIPS (lpj=31666428)
Total of 2 processors activated (12665.99 BogoMIPS).
....
Case 2: Some thing (presumably the SMM interrupt?) causing the
very low increase in TSC counter for the DELAY_CALIBRATION_TICKS
increase in jiffies
...
Calibrating delay loop (skipped), value calculated using timer
frequency.. 6333.25 BogoMIPS (lpj=31666270)
...
calibrate_delay_direct() timer_rate_max=31666483
timer_rate_min=31666074 pre_start=4199536526 pre_end=4231202809
calibrate_delay_direct() timer_rate_max=864348 timer_rate_min=864016
pre_start=2405343672 pre_end=2406207897
calibrate_delay_direct() timer_rate_max=31666483
timer_rate_min=31666179 pre_start=2469540464 pre_end=2501206823
calibrate_delay_direct() timer_rate_max=31666511
timer_rate_min=31666122 pre_start=2564539400 pre_end=2596205712
calibrate_delay_direct() timer_rate_max=31666084
timer_rate_min=31665685 pre_start=2659538782 pre_end=2691204657
calibrate_delay_direct() dropping min bogoMips estimate 1 = 864348
Calibrating delay using timer specific routine.. 6333.27 BogoMIPS (lpj=31666390)
Total of 2 processors activated (12666.53 BogoMIPS).
...
After 70 boots I saw 2 variations <1% slip through
Andrew Worsley
On Thu, 10 Mar 2011 17:03:51 +1100
Andrew Worsley <[email protected]> wrote:
> Please find attach a fix to the TSC (Time Stamp Counter) based
> bogoMIPS calculation used on secondary CPUs which has two faults:
Phil, you've had your nose in init/calibrate.c recently. Would you
have time to review Andrew's changes? Thanks.
Andrew, the patch was mssing a signed-off-by:. Please review the
description of this in Docuemntations/SubmuittingPatches and then, if
agreeable, send one along?
From: Andrew Worsley <[email protected]>
A fix to the TSC (Time Stamp Counter) based bogoMIPS calculation used on
secondary CPUs which has two faults:
1: Not handling wrapping of the lower 32 bits of the TSC counter on
32bit kernel - perhaps TSC is not reset by a warm reset?
2: TSC and Jiffies are no incrementing together properly. Either
jiffies increment too quickly or Time Stamp Counter isn't incremented
in during an SMI but the real time clock is and jiffies are
incremented.
Case 1 can result in a factor of 16 too large a value which makes udelay()
values too small and can cause mysterious driver errors. Case 2 appears
to give smaller 10-15% errors after averaging but enough to cause
occasional failures on my own board
I have tested this code on my own branch and attach patch suitable for
current kernel code. See below for examples of the failures and how the
fix handles these situations now.
I reported this issue earlier here:
Intermittent problem with BogoMIPs calculation on Intel AP CPUs -
http://marc.info/?l=linux-kernel&m=129947246316875&w=4
I suspect this issue has been seen by others but as it is intermittent and
bogoMIPS for secondary CPUs are no longer printed out it might have been
difficult to identify this as the cause. Perhaps these unresolved issues,
although quite old, might be relevant as possibly this fault has been
around for a while. In particular Case 1 may only be relevant to 32bit
kernels on newer HW (most people run 64bit kernels?). Case 2 is less
dramatic since the earlier fix in this area and also intermittent.
Re: bogomips discrepancy on Intel Core2 Quad CPU -
http://marc.info/?l=linux-kernel&m=118929277524298&w=4
slow system and bogus bogomips -
http://marc.info/?l=linux-kernel&m=116791286716107&w=4
Re: Re: [RFC-PATCH] clocksource: update lpj if clocksource has -
http://marc.info/?l=linux-kernel&m=128952775819467&w=4
This issue is masked a little by commit feae3203d711db0a ("timers, init:
Limit the number of per cpu calibration bootup messages") which only
prints out the first bogoMIPS value making it much harder to notice other
values differing. Perhaps it should be changed to only suppress them when
they are similar values?
Here are some outputs showing faults occurring and the new code handling
them properly. See my earlier message for examples of the original
failure.
Case 1: A Time Stamp Counter wrap:
...
Calibrating delay loop (skipped), value calculated using timer
frequency.. 6332.70 BogoMIPS (lpj=31663540)
....
calibrate_delay_direct() timer_rate_max=31666493
timer_rate_min=31666151 pre_start=4170369255 pre_end=4202035539
calibrate_delay_direct() timer_rate_max=2425955274
timer_rate_min=2425954941 pre_start=4265368533 pre_end=2396356387
calibrate_delay_direct() ignoring timer_rate as we had a TSC wrap
around start=4265368581 >=post_end=2396356511
calibrate_delay_direct() timer_rate_max=31666274
timer_rate_min=31665942 pre_start=2440373374 pre_end=2472039515
calibrate_delay_direct() timer_rate_max=31666492
timer_rate_min=31666160 pre_start=2535372139 pre_end=2567038422
calibrate_delay_direct() timer_rate_max=31666455
timer_rate_min=31666207 pre_start=2630371084 pre_end=2662037415
Calibrating delay using timer specific routine.. 6333.28 BogoMIPS (lpj=31666428)
Total of 2 processors activated (12665.99 BogoMIPS).
....
Case 2: Some thing (presumably the SMM interrupt?) causing the
very low increase in TSC counter for the DELAY_CALIBRATION_TICKS
increase in jiffies
...
Calibrating delay loop (skipped), value calculated using timer
frequency.. 6333.25 BogoMIPS (lpj=31666270)
...
calibrate_delay_direct() timer_rate_max=31666483
timer_rate_min=31666074 pre_start=4199536526 pre_end=4231202809
calibrate_delay_direct() timer_rate_max=864348 timer_rate_min=864016
pre_start=2405343672 pre_end=2406207897
calibrate_delay_direct() timer_rate_max=31666483
timer_rate_min=31666179 pre_start=2469540464 pre_end=2501206823
calibrate_delay_direct() timer_rate_max=31666511
timer_rate_min=31666122 pre_start=2564539400 pre_end=2596205712
calibrate_delay_direct() timer_rate_max=31666084
timer_rate_min=31665685 pre_start=2659538782 pre_end=2691204657
calibrate_delay_direct() dropping min bogoMips estimate 1 = 864348
Calibrating delay using timer specific routine.. 6333.27 BogoMIPS (lpj=31666390)
Total of 2 processors activated (12666.53 BogoMIPS).
...
After 70 boots I saw 2 variations <1% slip through
Cc: Phil Carmody <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
---
init/calibrate.c | 70 +++++++++++++++++++++++++++++++++++++++++----
1 file changed, 65 insertions(+), 5 deletions(-)
diff -puN init/calibrate.c~init-calibratec-fix-for-critical-bogomips-intermittent-calculation-failure init/calibrate.c
--- a/init/calibrate.c~init-calibratec-fix-for-critical-bogomips-intermittent-calculation-failure
+++ a/init/calibrate.c
@@ -38,6 +38,9 @@ static unsigned long __cpuinit calibrate
unsigned long timer_rate_min, timer_rate_max;
unsigned long good_timer_sum = 0;
unsigned long good_timer_count = 0;
+ unsigned long measured_times[MAX_DIRECT_CALIBRATION_RETRIES];
+ int max = -1; /* index of measured_times with max/min values or not set */
+ int min = -1;
int i;
if (read_current_timer(&pre_start) < 0 )
@@ -90,17 +93,74 @@ static unsigned long __cpuinit calibrate
* If the upper limit and lower limit of the timer_rate is
* >= 12.5% apart, redo calibration.
*/
- if (pre_start != 0 && pre_end != 0 &&
+ printk(KERN_DEBUG
+"calibrate_delay_direct() timer_rate_max=%lu timer_rate_min=%lu pre_start=%lu pre_end=%lu\n",
+ timer_rate_max, timer_rate_min, pre_start, pre_end);
+ if (start >= post_end)
+ printk(KERN_NOTICE
+ "calibrate_delay_direct() ignoring timer_rate as we had a TSC wrap around start=%lu >=post_end=%lu\n",
+ start, post_end);
+ if (start < post_end && pre_start != 0 && pre_end != 0 &&
(timer_rate_max - timer_rate_min) < (timer_rate_max >> 3)) {
good_timer_count++;
good_timer_sum += timer_rate_max;
- }
+ measured_times[i] = timer_rate_max;
+ if (max < 0 || timer_rate_max > measured_times[max])
+ max = i;
+ if (min < 0 || timer_rate_max < measured_times[min])
+ min = i;
+ } else
+ measured_times[i] = 0;
+
}
- if (good_timer_count)
- return (good_timer_sum/good_timer_count);
+ /*
+ * Find the maximum & minimum - if they differ too much throw out the one with
+ * the largest difference from the mean and try again...
+ */
+ while (good_timer_count > 1) {
+ unsigned long estimate;
+ unsigned long maxdiff;
+
+ /* compute the estimate */
+ estimate = (good_timer_sum/good_timer_count);
+ maxdiff = estimate >> 3;
+
+ /* if range is within 12% let's take it */
+ if ((measured_times[max] - measured_times[min]) < maxdiff)
+ return (estimate);
+
+ /* ok - drop the worse value and try again... */
+ good_timer_sum = 0;
+ good_timer_count = 0;
+ if ((measured_times[max] - estimate) < (estimate - measured_times[min])) {
+ printk(KERN_NOTICE
+ "calibrate_delay_direct() dropping min bogoMips estimate %d = %lu\n",
+ min, measured_times[min]);
+ measured_times[min] = 0;
+ min = max;
+ } else {
+ printk(KERN_NOTICE
+ "calibrate_delay_direct() dropping max bogoMips estimate %d = %lu\n",
+ max, measured_times[max]);
+ measured_times[max] = 0;
+ max = min;
+ }
+
+ for (i = 0; i < MAX_DIRECT_CALIBRATION_RETRIES; i++) {
+ if (measured_times[i] == 0)
+ continue;
+ good_timer_count++;
+ good_timer_sum += measured_times[i];
+ if (measured_times[i] < measured_times[min])
+ min = i;
+ if (measured_times[i] > measured_times[max])
+ max = i;
+ }
+
+ }
- printk(KERN_WARNING "calibrate_delay_direct() failed to get a good "
+ printk(KERN_NOTICE "calibrate_delay_direct() failed to get a good "
"estimate for loops_per_jiffy.\nProbably due to long platform interrupts. Consider using \"lpj=\" boot option.\n");
return 0;
}
_
On 07/04/11 15:17 -0700, ext Andrew Morton wrote:
> On Thu, 10 Mar 2011 17:03:51 +1100
> Andrew Worsley <[email protected]> wrote:
>
> > Please find attach a fix to the TSC (Time Stamp Counter) based
> > bogoMIPS calculation used on secondary CPUs which has two faults:
>
> Phil, you've had your nose in init/calibrate.c recently. Would you
> have time to review Andrew's changes? Thanks.
No problem. Nokia's trained me to be a bit pedantic, so I noticed a few
style issues or niggles.
> Andrew, the patch was mssing a signed-off-by:. Please review the
> description of this in Docuemntations/SubmuittingPatches and then, if
> agreeable, send one along?
>
>
>
> From: Andrew Worsley <[email protected]>
>
> A fix to the TSC (Time Stamp Counter) based bogoMIPS calculation used on
> secondary CPUs which has two faults:
>
> 1: Not handling wrapping of the lower 32 bits of the TSC counter on
> 32bit kernel - perhaps TSC is not reset by a warm reset?
>
> 2: TSC and Jiffies are no incrementing together properly. Either
> jiffies increment too quickly or Time Stamp Counter isn't incremented
> in during an SMI but the real time clock is and jiffies are
> incremented.
>
> Case 1 can result in a factor of 16 too large a value which makes udelay()
> values too small and can cause mysterious driver errors. Case 2 appears
> to give smaller 10-15% errors after averaging but enough to cause
> occasional failures on my own board
>
> I have tested this code on my own branch and attach patch suitable for
> current kernel code. See below for examples of the failures and how the
> fix handles these situations now.
>
> I reported this issue earlier here:
> Intermittent problem with BogoMIPs calculation on Intel AP CPUs -
> http://marc.info/?l=linux-kernel&m=129947246316875&w=4
>
> I suspect this issue has been seen by others but as it is intermittent and
> bogoMIPS for secondary CPUs are no longer printed out it might have been
> difficult to identify this as the cause. Perhaps these unresolved issues,
> although quite old, might be relevant as possibly this fault has been
> around for a while. In particular Case 1 may only be relevant to 32bit
> kernels on newer HW (most people run 64bit kernels?). Case 2 is less
> dramatic since the earlier fix in this area and also intermittent.
>
> Re: bogomips discrepancy on Intel Core2 Quad CPU -
> http://marc.info/?l=linux-kernel&m=118929277524298&w=4
> slow system and bogus bogomips -
> http://marc.info/?l=linux-kernel&m=116791286716107&w=4
> Re: Re: [RFC-PATCH] clocksource: update lpj if clocksource has -
> http://marc.info/?l=linux-kernel&m=128952775819467&w=4
>
> This issue is masked a little by commit feae3203d711db0a ("timers, init:
> Limit the number of per cpu calibration bootup messages") which only
> prints out the first bogoMIPS value making it much harder to notice other
> values differing. Perhaps it should be changed to only suppress them when
> they are similar values?
>
> Here are some outputs showing faults occurring and the new code handling
> them properly. See my earlier message for examples of the original
> failure.
>
> Case 1: A Time Stamp Counter wrap:
> ...
> Calibrating delay loop (skipped), value calculated using timer
> frequency.. 6332.70 BogoMIPS (lpj=31663540)
> ....
> calibrate_delay_direct() timer_rate_max=31666493
> timer_rate_min=31666151 pre_start=4170369255 pre_end=4202035539
> calibrate_delay_direct() timer_rate_max=2425955274
> timer_rate_min=2425954941 pre_start=4265368533 pre_end=2396356387
> calibrate_delay_direct() ignoring timer_rate as we had a TSC wrap
> around start=4265368581 >=post_end=2396356511
> calibrate_delay_direct() timer_rate_max=31666274
> timer_rate_min=31665942 pre_start=2440373374 pre_end=2472039515
> calibrate_delay_direct() timer_rate_max=31666492
> timer_rate_min=31666160 pre_start=2535372139 pre_end=2567038422
> calibrate_delay_direct() timer_rate_max=31666455
> timer_rate_min=31666207 pre_start=2630371084 pre_end=2662037415
> Calibrating delay using timer specific routine.. 6333.28 BogoMIPS (lpj=31666428)
> Total of 2 processors activated (12665.99 BogoMIPS).
> ....
>
> Case 2: Some thing (presumably the SMM interrupt?) causing the
> very low increase in TSC counter for the DELAY_CALIBRATION_TICKS
> increase in jiffies
> ...
> Calibrating delay loop (skipped), value calculated using timer
> frequency.. 6333.25 BogoMIPS (lpj=31666270)
> ...
> calibrate_delay_direct() timer_rate_max=31666483
> timer_rate_min=31666074 pre_start=4199536526 pre_end=4231202809
> calibrate_delay_direct() timer_rate_max=864348 timer_rate_min=864016
> pre_start=2405343672 pre_end=2406207897
> calibrate_delay_direct() timer_rate_max=31666483
> timer_rate_min=31666179 pre_start=2469540464 pre_end=2501206823
> calibrate_delay_direct() timer_rate_max=31666511
> timer_rate_min=31666122 pre_start=2564539400 pre_end=2596205712
> calibrate_delay_direct() timer_rate_max=31666084
> timer_rate_min=31665685 pre_start=2659538782 pre_end=2691204657
> calibrate_delay_direct() dropping min bogoMips estimate 1 = 864348
> Calibrating delay using timer specific routine.. 6333.27 BogoMIPS (lpj=31666390)
> Total of 2 processors activated (12666.53 BogoMIPS).
> ...
>
> After 70 boots I saw 2 variations <1% slip through
>
> Cc: Phil Carmody <[email protected]>
> Signed-off-by: Andrew Morton <[email protected]>
> ---
>
> init/calibrate.c | 70 +++++++++++++++++++++++++++++++++++++++++----
> 1 file changed, 65 insertions(+), 5 deletions(-)
>
> diff -puN init/calibrate.c~init-calibratec-fix-for-critical-bogomips-intermittent-calculation-failure init/calibrate.c
> --- a/init/calibrate.c~init-calibratec-fix-for-critical-bogomips-intermittent-calculation-failure
> +++ a/init/calibrate.c
> @@ -38,6 +38,9 @@ static unsigned long __cpuinit calibrate
> unsigned long timer_rate_min, timer_rate_max;
> unsigned long good_timer_sum = 0;
> unsigned long good_timer_count = 0;
> + unsigned long measured_times[MAX_DIRECT_CALIBRATION_RETRIES];
> + int max = -1; /* index of measured_times with max/min values or not set */
> + int min = -1;
> int i;
>
> if (read_current_timer(&pre_start) < 0 )
> @@ -90,17 +93,74 @@ static unsigned long __cpuinit calibrate
> * If the upper limit and lower limit of the timer_rate is
> * >= 12.5% apart, redo calibration.
> */
> - if (pre_start != 0 && pre_end != 0 &&
> + printk(KERN_DEBUG
> +"calibrate_delay_direct() timer_rate_max=%lu timer_rate_min=%lu pre_start=%lu pre_end=%lu\n",
> + timer_rate_max, timer_rate_min, pre_start, pre_end);
> + if (start >= post_end)
> + printk(KERN_NOTICE
> + "calibrate_delay_direct() ignoring timer_rate as we had a TSC wrap around start=%lu >=post_end=%lu\n",
> + start, post_end);
> + if (start < post_end && pre_start != 0 && pre_end != 0 &&
This could be split off into a separate patch, as it is independent of the rest of the patch.
> (timer_rate_max - timer_rate_min) < (timer_rate_max >> 3)) {
> good_timer_count++;
> good_timer_sum += timer_rate_max;
> - }
> + measured_times[i] = timer_rate_max;
> + if (max < 0 || timer_rate_max > measured_times[max])
> + max = i;
> + if (min < 0 || timer_rate_max < measured_times[min])
> + min = i;
> + } else
> + measured_times[i] = 0;
Inconsistent use of {}.
> +
> }
>
> - if (good_timer_count)
> - return (good_timer_sum/good_timer_count);
> + /*
> + * Find the maximum & minimum - if they differ too much throw out the one with
> + * the largest difference from the mean and try again...
> + */
> + while (good_timer_count > 1) {
> + unsigned long estimate;
> + unsigned long maxdiff;
> +
> + /* compute the estimate */
> + estimate = (good_timer_sum/good_timer_count);
Unnecessary (), no spaces around / operator.
> + maxdiff = estimate >> 3;
> +
> + /* if range is within 12% let's take it */
> + if ((measured_times[max] - measured_times[min]) < maxdiff)
> + return (estimate);
Unnecessary ().
> +
> + /* ok - drop the worse value and try again... */
> + good_timer_sum = 0;
> + good_timer_count = 0;
> + if ((measured_times[max] - estimate) < (estimate - measured_times[min])) {
> + printk(KERN_NOTICE
> + "calibrate_delay_direct() dropping min bogoMips estimate %d = %lu\n",
> + min, measured_times[min]);
> + measured_times[min] = 0;
> + min = max;
> + } else {
> + printk(KERN_NOTICE
> + "calibrate_delay_direct() dropping max bogoMips estimate %d = %lu\n",
You could squash those two strings into one with a %s, and trust the compiler to
do the right thing. However, apart from those, there are no functional problems.
I currently do not have a system upon which I can test the patch, alas.
Reviewed-by: Phil Carmody <[email protected]>
Phil
> + max, measured_times[max]);
> + measured_times[max] = 0;
> + max = min;
> + }
> +
> + for (i = 0; i < MAX_DIRECT_CALIBRATION_RETRIES; i++) {
> + if (measured_times[i] == 0)
> + continue;
> + good_timer_count++;
> + good_timer_sum += measured_times[i];
> + if (measured_times[i] < measured_times[min])
> + min = i;
> + if (measured_times[i] > measured_times[max])
> + max = i;
> + }
> +
> + }
>
> - printk(KERN_WARNING "calibrate_delay_direct() failed to get a good "
> + printk(KERN_NOTICE "calibrate_delay_direct() failed to get a good "
> "estimate for loops_per_jiffy.\nProbably due to long platform interrupts. Consider using \"lpj=\" boot option.\n");
> return 0;
> }
> _
On Thu, 2011-04-07 at 15:17 -0700, Andrew Morton wrote:
> On Thu, 10 Mar 2011 17:03:51 +1100
> Andrew Worsley <[email protected]> wrote:
>
> Cc: Phil Carmody <[email protected]>
> Signed-off-by: Andrew Morton <[email protected]>
> ---
>
> init/calibrate.c | 70 +++++++++++++++++++++++++++++++++++++++++----
> 1 file changed, 65 insertions(+), 5 deletions(-)
>
> diff -puN init/calibrate.c~init-calibratec-fix-for-critical-bogomips-intermittent-calculation-failure init/calibrate.c
> --- a/init/calibrate.c~init-calibratec-fix-for-critical-bogomips-intermittent-calculation-failure
> +++ a/init/calibrate.c
> @@ -38,6 +38,9 @@ static unsigned long __cpuinit calibrate
> unsigned long timer_rate_min, timer_rate_max;
> unsigned long good_timer_sum = 0;
> unsigned long good_timer_count = 0;
> + unsigned long measured_times[MAX_DIRECT_CALIBRATION_RETRIES];
> + int max = -1; /* index of measured_times with max/min values or not set */
> + int min = -1;
> int i;
>
> if (read_current_timer(&pre_start) < 0 )
> @@ -90,17 +93,74 @@ static unsigned long __cpuinit calibrate
> * If the upper limit and lower limit of the timer_rate is
> * >= 12.5% apart, redo calibration.
> */
> - if (pre_start != 0 && pre_end != 0 &&
> + printk(KERN_DEBUG
> +"calibrate_delay_direct() timer_rate_max=%lu timer_rate_min=%lu pre_start=%lu pre_end=%lu\n",
> + timer_rate_max, timer_rate_min, pre_start, pre_end);
Can we please remove this printk(), I'm not really enjoying the 120
lines of dmesg spew this creates on my dev-box.
Signed-off-by: Peter Zijlstra <[email protected]>
---
init/calibrate.c | 6 ++----
1 files changed, 2 insertions(+), 4 deletions(-)
diff --git a/init/calibrate.c b/init/calibrate.c
index cfd7000..a24efd3 100644
--- a/init/calibrate.c
+++ b/init/calibrate.c
@@ -93,14 +93,12 @@ static unsigned long __cpuinit calibrate_delay_direct(void)
* If the upper limit and lower limit of the timer_rate is
* >= 12.5% apart, redo calibration.
*/
- printk(KERN_DEBUG "calibrate_delay_direct() timer_rate_max=%lu "
- "timer_rate_min=%lu pre_start=%lu pre_end=%lu\n",
- timer_rate_max, timer_rate_min, pre_start, pre_end);
- if (start >= post_end)
+ if (start >= post_end) {
printk(KERN_NOTICE "calibrate_delay_direct() ignoring "
"timer_rate as we had a TSC wrap around"
" start=%lu >=post_end=%lu\n",
start, post_end);
+ }
if (start < post_end && pre_start != 0 && pre_end != 0 &&
(timer_rate_max - timer_rate_min) < (timer_rate_max >> 3)) {
good_timer_count++;