Mailing List Archive: Linux: Kernel

Kernel 2.6.27.7-9 for Suse 11.1 help required with CPU Clock freq/speed/ticks

Index | Next | Previous | View Threaded

Subhan.Ahmed at baesystems

Nov 19, 2009, 4:32 AM

Post #1 of 6 (337 views)
Permalink

Kernel 2.6.27.7-9 for Suse 11.1 help required with CPU Clock freq/speed/ticks

Hi All,

I know this is not email list for programming questions but it relates
to Kernel as well, in fact relying on kernel. Could someone please
through a light or guide me to the right direction.

Problem Statement: High CPU clock speed/freq
Requirement: Obtain a stable CPU clock ticks/speed/freq on
Suse 11.1 with kernel 2.6.27.7-9
Questions: Please refer to the bottom of this page
Artifacts in Use:
-----------------------------------
OS: Suse 11.1
GCC Version: 4.3.2 (Suse Linux) [gcc_4_3-brach revision
141291]
Kernel: 2.6.27.7-9
Kernel Mods:
* Un-check the Tickless option
* Timer Frequency - 1000Hz
* Preempt kernel

Others 1
-----------
OS: Suse 10.2
GCC Version: 4.1.2 20061115 (prerelease)(SUSE Linux)
Kernel: 2.6.18.2-34-default
Kernel Mods:
* Preemptible Kernel
(Low-Latency Desktop) (NEW)
* Preempt The Big Kernel Lock
(NEW)
* Timer frequency (NEW) - 1000
Hz (NEW)

Others 2
-----------
OS: Suse 9.3
GCC Version: 3.3.5 20050117 (prerelease)(SUSE Linux)
Kernel 2.6.11.4-20a-default
Kernel Mods: None

I executed the following c++ code on the above stated builds

CODE - file name test.cpp
#include <signal.h>
#include <sys/time.h>
#include <iostream>
#include <cstdlib>

using namespace std;

long long int counter = 0;
struct timeval last_time;
struct timeval curr_time;
double dif = 0.0;
double freq_sum = 0.0;
double reps = 0.0;
double freq_min = 99999.0;
double freq_max = 0.0;
long long int num_too_low = 0;

void time_check(int data)
{
// work out the frequecy of the SIGALRMs
++counter;
if (counter >= 1000)
{

// need to work out time since last 1000 ticks
gettimeofday(&curr_time, NULL);
dif = ((curr_time.tv_usec + curr_time.tv_sec * 1000000)
- (last_time.tv_usec + last_time.tv_sec * 1000000));
double freq = (counter / dif) * 1000000;

freq_sum = ((freq_sum * reps) + freq) / (reps + 1) ;

++reps;
cout << "Frequency = " << freq << " reps= " << dif / 1000000 <<
endl;
if (freq_min > freq) freq_min = freq;
if (freq_max < freq) freq_max = freq;
if (freq < 950)
++num_too_low;
last_time = curr_time;
counter = 0;
}
}

int main (int argc, char * argv[])
{
cout << "go" /* << "\a \a \a" */ << endl;

int res;
gettimeofday(&last_time, NULL);
struct sigaction action;

struct itimerval timer_value;

timer_value.it_value.tv_sec = 0;
timer_value.it_value.tv_usec = 1;
timer_value.it_interval.tv_sec = 0;
timer_value.it_interval.tv_usec = 1;

action.sa_handler = time_check;
action.sa_flags = SA_NOMASK;
sigemptyset(&action.sa_mask);

sigaction( SIGALRM, &action, NULL);
res = setitimer( ITIMER_REAL, &timer_value, NULL );
if (res == -1)
cout << "error in setitimer" << endl;

cout << "Starting CPU Test program" << endl;
// loop for a long time

while (reps < 3000.0)
{
sleep(1);
}
cout << "average CPU frequency = " << freq_sum << endl;
cout << "reps = " << reps << endl;
cout << "Min = " << freq_min << " Max = " << freq_max << endl;
cout << "number of low = " << num_too_low << endl;
return 0;
}

Compiled the above code with "g++ -o test test.cpp"
Run the above code with "./test"

Observations:
SUSE Version AVG. Frequency AVG. REPS
Suse 9.3 999.xxx to 990.xxx reps > 1
(on average)
Suse 10.2 999.xxx to 998.xxx reps (1
- 1.001)
Suse 10.3 1000.xxx to 912.xxx reps (1 - 1.090)
Suse 11.1 0 to 324263.xxx reps
(-2e-0.6 upto 0.005112)

Suse 11.1 - Options:

- Turn off ACPI in options when booting with clock=tsc | clock=pit

Observations for suse 11.1 with options acpi=off and clock=tsc |
clock=pit

SUSE Version AVG. Frequency AVG. REPS
Suse 11.1 710.xxx to 999.xxx reps
(1.37xx to 1.0002)

Hardware used for Suse 11.1 - HP Pavilion Slimline s3821uk Desktop PC
(NQ808AA) specifications - HP Home & Home Office products
http://h10010.www1.hp.com/wwpc/uk/en/ho/WF10a/12454-12454-3329740-64546-
64546-3884669.html?jumpid=in_r2515_uk/en/hho/ipg/psc404redirect-ot-xx-xx
-/chev/

While testing no other application/s were running.

Question:

* Is my c++ code correct?
* Am I using the correct way to get the clock ticks or is there more
reliable tchnique avaliable to do this?
* Is that a problem with new Kernel if so is it a known issue ?
* Do I need to modify the Kernel to obtain regular and stable clock tick
at 1000 Hz ?
* Do I have to upgrade the Kernel ?
* Would be great, if pointed to the right direction for solution (e.g.
another forum) if no solution at hand.

Thanks

********************************************************************
This email and any attachments are confidential to the intended
recipient and may also be privileged. If you are not the intended
recipient please delete it from your system and notify the sender.
You should not copy it or use it for any purpose nor disclose or
distribute its contents to any other person.
********************************************************************

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo [at] vger
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

Subhan.Ahmed at baesystems

Nov 19, 2009, 10:48 AM

Post #2 of 6 (309 views)
Permalink

Kernel 2.6.27.7-9 for Suse 11.1 help required with CPU Clock freq/speed/ticks [In reply to]

Subhan.Ahmed at baesystems

Nov 20, 2009, 2:57 AM

Post #3 of 6 (299 views)
Permalink

Kernel 2.6.27.7-9 for Suse 11.1 help required with CPU Clock freq/speed/ticks [In reply to]

Hi All,

I know this is not email list for programming questions but it relates
to Kernel as well, in fact relying on kernel. Could someone please
through a light or guide me to the right direction.

Problem Statement: High CPU clock speed/freq
Requirement: Obtain a stable CPU clock ticks/speed/freq on
Suse 11.1 with kernel 2.6.27.7-9
Questions: Please refer to the bottom of this page
Artifacts in Use:
-----------------------------------
OS: Suse 11.1
GCC Version: 4.3.2 (Suse Linux) [gcc_4_3-brach revision
141291]
Kernel: 2.6.27.7-9
Kernel Mods:
* Un-check the Tickless option
* Timer Frequency - 1000Hz
* Preempt kernel

Others 1
-----------
OS: Suse 10.2
GCC Version: 4.1.2 20061115 (prerelease)(SUSE Linux)
Kernel: 2.6.18.2-34-default
Kernel Mods:
* Preemptible Kernel
(Low-Latency Desktop) (NEW)
* Preempt The Big Kernel Lock
(NEW)
* Timer frequency (NEW) - 1000
Hz (NEW)

Others 2
-----------
OS: Suse 9.3
GCC Version: 3.3.5 20050117 (prerelease)(SUSE Linux)
Kernel 2.6.11.4-20a-default
Kernel Mods: None

I executed the following c++ code on the above stated builds

CODE - file name test.cpp
#include <signal.h>
#include <sys/time.h>
#include <iostream>
#include <cstdlib>

using namespace std;

long long int counter = 0;
struct timeval last_time;
struct timeval curr_time;
double dif = 0.0;
double freq_sum = 0.0;
double reps = 0.0;
double freq_min = 99999.0;
double freq_max = 0.0;
long long int num_too_low = 0;

void time_check(int data)
{
// work out the frequecy of the SIGALRMs
++counter;
if (counter >= 1000)
{

// need to work out time since last 1000 ticks
gettimeofday(&curr_time, NULL);
dif = ((curr_time.tv_usec + curr_time.tv_sec * 1000000)
- (last_time.tv_usec + last_time.tv_sec * 1000000));
double freq = (counter / dif) * 1000000;

freq_sum = ((freq_sum * reps) + freq) / (reps + 1) ;

++reps;
cout << "Frequency = " << freq << " reps= " << dif / 1000000 <<
endl;
if (freq_min > freq) freq_min = freq;
if (freq_max < freq) freq_max = freq;
if (freq < 950)
++num_too_low;
last_time = curr_time;
counter = 0;
}
}

int main (int argc, char * argv[])
{
cout << "go" /* << "\a \a \a" */ << endl;

int res;
gettimeofday(&last_time, NULL);
struct sigaction action;

struct itimerval timer_value;

timer_value.it_value.tv_sec = 0;
timer_value.it_value.tv_usec = 1;
timer_value.it_interval.tv_sec = 0;
timer_value.it_interval.tv_usec = 1;

action.sa_handler = time_check;
action.sa_flags = SA_NOMASK;
sigemptyset(&action.sa_mask);

sigaction( SIGALRM, &action, NULL);
res = setitimer( ITIMER_REAL, &timer_value, NULL );
if (res == -1)
cout << "error in setitimer" << endl;

cout << "Starting CPU Test program" << endl;
// loop for a long time

while (reps < 3000.0)
{
sleep(1);
}
cout << "average CPU frequency = " << freq_sum << endl;
cout << "reps = " << reps << endl;
cout << "Min = " << freq_min << " Max = " << freq_max << endl;
cout << "number of low = " << num_too_low << endl;
return 0;
}

Compiled the above code with "g++ -o test test.cpp"
Run the above code with "./test"

Observations:
SUSE Version AVG. Frequency AVG. REPS
Suse 9.3 999.xxx to 990.xxx reps > 1
(on average)
Suse 10.2 999.xxx to 998.xxx reps (1
- 1.001)
Suse 10.3 1000.xxx to 912.xxx reps (1 - 1.090)
Suse 11.1 0 to 324263.xxx reps
(-2e-0.6 upto 0.005112)

Suse 11.1 - Options:

- Turn off ACPI in options when booting with clock=tsc | clock=pit

Observations for suse 11.1 with options acpi=off and clock=tsc |
clock=pit

SUSE Version AVG. Frequency AVG. REPS
Suse 11.1 710.xxx to 999.xxx reps
(1.37xx to 1.0002)

Hardware used for Suse 11.1 - HP Pavilion Slimline s3821uk Desktop PC
(NQ808AA) specifications - HP Home & Home Office products
http://h10010.www1.hp.com/wwpc/uk/en/ho/WF10a/12454-12454-3329740-64546-
64546-3884669.html?jumpid=in_r2515_uk/en/hho/ipg/psc404redirect-ot-xx-xx
-/chev/

While testing no other application/s were running.

Question:

* Is my c++ code correct?
* Am I using the correct way to get the clock ticks or is there more
reliable tchnique avaliable to do this?
* Is that a problem with new Kernel if so is it a known issue ?
* Do I need to modify the Kernel to obtain regular and stable clock tick
at 1000 Hz ?
* Do I have to upgrade the Kernel ?
* Would be great, if pointed to the right direction for solution (e.g.
another forum) if no solution at hand.

Thanks

Subhan

********************************************************************
This email and any attachments are confidential to the intended
recipient and may also be privileged. If you are not the intended
recipient please delete it from your system and notify the sender.
You should not copy it or use it for any purpose nor disclose or
distribute its contents to any other person.
********************************************************************

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo [at] vger
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

Subhan.Ahmed at baesystems

Nov 23, 2009, 6:47 AM

Post #4 of 6 (291 views)
Permalink

RE: Kernel 2.6.27.7-9 for Suse 11.1 help required with CPU Clock freq/speed/ticks [In reply to]

Hi All,

I have requested response on below, I can hold on and wait if someone
can help on this but do let me know if this is not the right place to
ask such questions. Thanks for help.

Subhan

-----Original Message-----
From: linux-kernel-owner [at] vger
[mailto:linux-kernel-owner [at] vger] On Behalf Of Ahmed, Subhan
(UK)
Sent: 20 November 2009 10:58
To: linux-kernel [at] vger
Subject: Kernel 2.6.27.7-9 for Suse 11.1 help required with CPU Clock
freq/speed/ticks

*** WARNING ***

This message has originated outside your organisation,
either from an external partner or the Global Internet.
Keep this in mind if you answer this message.

Hi All,

I know this is not email list for programming questions but it relates
to Kernel as well, in fact relying on kernel. Could someone please
through a light or guide me to the right direction.

Problem Statement: High CPU clock speed/freq
Requirement: Obtain a stable CPU clock ticks/speed/freq on
Suse 11.1 with kernel 2.6.27.7-9
Questions: Please refer to the bottom of this page
Artifacts in Use:
-----------------------------------
OS: Suse 11.1
GCC Version: 4.3.2 (Suse Linux) [gcc_4_3-brach revision
141291]
Kernel: 2.6.27.7-9
Kernel Mods:
* Un-check the Tickless option
* Timer Frequency - 1000Hz
* Preempt kernel

Others 1
-----------
OS: Suse 10.2
GCC Version: 4.1.2 20061115 (prerelease)(SUSE Linux)
Kernel: 2.6.18.2-34-default
Kernel Mods:
* Preemptible Kernel
(Low-Latency Desktop) (NEW)
* Preempt The Big Kernel Lock
(NEW)
* Timer frequency (NEW) - 1000
Hz (NEW)

Others 2
-----------
OS: Suse 9.3
GCC Version: 3.3.5 20050117 (prerelease)(SUSE Linux)
Kernel 2.6.11.4-20a-default
Kernel Mods: None

I executed the following c++ code on the above stated builds

CODE - file name test.cpp
#include <signal.h>
#include <sys/time.h>
#include <iostream>
#include <cstdlib>

using namespace std;

long long int counter = 0;
struct timeval last_time;
struct timeval curr_time;
double dif = 0.0;
double freq_sum = 0.0;
double reps = 0.0;
double freq_min = 99999.0;
double freq_max = 0.0;
long long int num_too_low = 0;

void time_check(int data)
{
// work out the frequecy of the SIGALRMs
++counter;
if (counter >= 1000)
{

// need to work out time since last 1000 ticks
gettimeofday(&curr_time, NULL);
dif = ((curr_time.tv_usec + curr_time.tv_sec * 1000000)
- (last_time.tv_usec + last_time.tv_sec * 1000000));
double freq = (counter / dif) * 1000000;

freq_sum = ((freq_sum * reps) + freq) / (reps + 1) ;

++reps;
cout << "Frequency = " << freq << " reps= " << dif / 1000000 <<
endl;
if (freq_min > freq) freq_min = freq;
if (freq_max < freq) freq_max = freq;
if (freq < 950)
++num_too_low;
last_time = curr_time;
counter = 0;
}
}

int main (int argc, char * argv[])
{
cout << "go" /* << "\a \a \a" */ << endl;

int res;
gettimeofday(&last_time, NULL);
struct sigaction action;

struct itimerval timer_value;

timer_value.it_value.tv_sec = 0;
timer_value.it_value.tv_usec = 1;
timer_value.it_interval.tv_sec = 0;
timer_value.it_interval.tv_usec = 1;

action.sa_handler = time_check;
action.sa_flags = SA_NOMASK;
sigemptyset(&action.sa_mask);

sigaction( SIGALRM, &action, NULL);
res = setitimer( ITIMER_REAL, &timer_value, NULL );
if (res == -1)
cout << "error in setitimer" << endl;

cout << "Starting CPU Test program" << endl;
// loop for a long time

while (reps < 3000.0)
{
sleep(1);
}
cout << "average CPU frequency = " << freq_sum << endl;
cout << "reps = " << reps << endl;
cout << "Min = " << freq_min << " Max = " << freq_max << endl;
cout << "number of low = " << num_too_low << endl;
return 0;
}

Compiled the above code with "g++ -o test test.cpp"
Run the above code with "./test"

Observations:
SUSE Version AVG. Frequency AVG. REPS
Suse 9.3 999.xxx to 990.xxx reps > 1
(on average)
Suse 10.2 999.xxx to 998.xxx reps (1
- 1.001)
Suse 10.3 1000.xxx to 912.xxx reps (1 - 1.090)
Suse 11.1 0 to 324263.xxx reps
(-2e-0.6 upto 0.005112)

Suse 11.1 - Options:

- Turn off ACPI in options when booting with clock=tsc | clock=pit

Observations for suse 11.1 with options acpi=off and clock=tsc |
clock=pit

SUSE Version AVG. Frequency AVG. REPS
Suse 11.1 710.xxx to 999.xxx reps
(1.37xx to 1.0002)

Hardware used for Suse 11.1 - HP Pavilion Slimline s3821uk Desktop PC
(NQ808AA) specifications - HP Home & Home Office products
http://h10010.www1.hp.com/wwpc/uk/en/ho/WF10a/12454-12454-3329740-64546-
64546-3884669.html?jumpid=in_r2515_uk/en/hho/ipg/psc404redirect-ot-xx-xx
-/chev/

While testing no other application/s were running.

Question:

* Is my c++ code correct?
* Am I using the correct way to get the clock ticks or is there more
reliable tchnique avaliable to do this?
* Is that a problem with new Kernel if so is it a known issue ?
* Do I need to modify the Kernel to obtain regular and stable clock tick
at 1000 Hz ?
* Do I have to upgrade the Kernel ?
* Would be great, if pointed to the right direction for solution (e.g.
another forum) if no solution at hand.

Thanks

Subhan

********************************************************************
This email and any attachments are confidential to the intended
recipient and may also be privileged. If you are not the intended
recipient please delete it from your system and notify the sender.
You should not copy it or use it for any purpose nor disclose or
distribute its contents to any other person.
********************************************************************

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel"
in the body of a message to majordomo [at] vger More majordomo
info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo [at] vger
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

Subhan.Ahmed at baesystems

Nov 24, 2009, 3:41 AM

Post #5 of 6 (293 views)
Permalink

RE: Kernel 2.6.27.7-9 for Suse 11.1 help required with CPU Clock freq/speed/ticks [In reply to]

Is anyone getting this message at all.

-----Original Message-----
From: linux-kernel-owner [at] vger
[mailto:linux-kernel-owner [at] vger] On Behalf Of Ahmed, Subhan
(UK)
Sent: 23 November 2009 14:47
To: linux-kernel [at] vger
Subject: RE: Kernel 2.6.27.7-9 for Suse 11.1 help required with CPU
Clock freq/speed/ticks

*** WARNING ***

This message has originated outside your organisation,
either from an external partner or the Global Internet.
Keep this in mind if you answer this message.

Hi All,

I have requested response on below, I can hold on and wait if someone
can help on this but do let me know if this is not the right place to
ask such questions. Thanks for help.

Subhan

-----Original Message-----
From: linux-kernel-owner [at] vger
[mailto:linux-kernel-owner [at] vger] On Behalf Of Ahmed, Subhan
(UK)
Sent: 20 November 2009 10:58
To: linux-kernel [at] vger
Subject: Kernel 2.6.27.7-9 for Suse 11.1 help required with CPU Clock
freq/speed/ticks

*** WARNING ***

This message has originated outside your organisation,
either from an external partner or the Global Internet.
Keep this in mind if you answer this message.

Hi All,

I know this is not email list for programming questions but it relates
to Kernel as well, in fact relying on kernel. Could someone please
through a light or guide me to the right direction.

Problem Statement: High CPU clock speed/freq
Requirement: Obtain a stable CPU clock ticks/speed/freq on
Suse 11.1 with kernel 2.6.27.7-9
Questions: Please refer to the bottom of this page
Artifacts in Use:
-----------------------------------
OS: Suse 11.1
GCC Version: 4.3.2 (Suse Linux) [gcc_4_3-brach revision
141291]
Kernel: 2.6.27.7-9
Kernel Mods:
* Un-check the Tickless option
* Timer Frequency - 1000Hz
* Preempt kernel

Others 1
-----------
OS: Suse 10.2
GCC Version: 4.1.2 20061115 (prerelease)(SUSE Linux)
Kernel: 2.6.18.2-34-default
Kernel Mods:
* Preemptible Kernel
(Low-Latency Desktop) (NEW)
* Preempt The Big Kernel Lock
(NEW)
* Timer frequency (NEW) - 1000
Hz (NEW)

Others 2
-----------
OS: Suse 9.3
GCC Version: 3.3.5 20050117 (prerelease)(SUSE Linux)
Kernel 2.6.11.4-20a-default
Kernel Mods: None

I executed the following c++ code on the above stated builds

CODE - file name test.cpp
#include <signal.h>
#include <sys/time.h>
#include <iostream>
#include <cstdlib>

using namespace std;

long long int counter = 0;
struct timeval last_time;
struct timeval curr_time;
double dif = 0.0;
double freq_sum = 0.0;
double reps = 0.0;
double freq_min = 99999.0;
double freq_max = 0.0;
long long int num_too_low = 0;

void time_check(int data)
{
// work out the frequecy of the SIGALRMs
++counter;
if (counter >= 1000)
{

// need to work out time since last 1000 ticks
gettimeofday(&curr_time, NULL);
dif = ((curr_time.tv_usec + curr_time.tv_sec * 1000000)
- (last_time.tv_usec + last_time.tv_sec * 1000000));
double freq = (counter / dif) * 1000000;

freq_sum = ((freq_sum * reps) + freq) / (reps + 1) ;

++reps;
cout << "Frequency = " << freq << " reps= " << dif / 1000000 <<
endl;
if (freq_min > freq) freq_min = freq;
if (freq_max < freq) freq_max = freq;
if (freq < 950)
++num_too_low;
last_time = curr_time;
counter = 0;
}
}

int main (int argc, char * argv[])
{
cout << "go" /* << "\a \a \a" */ << endl;

int res;
gettimeofday(&last_time, NULL);
struct sigaction action;

struct itimerval timer_value;

timer_value.it_value.tv_sec = 0;
timer_value.it_value.tv_usec = 1;
timer_value.it_interval.tv_sec = 0;
timer_value.it_interval.tv_usec = 1;

action.sa_handler = time_check;
action.sa_flags = SA_NOMASK;
sigemptyset(&action.sa_mask);

sigaction( SIGALRM, &action, NULL);
res = setitimer( ITIMER_REAL, &timer_value, NULL );
if (res == -1)
cout << "error in setitimer" << endl;

cout << "Starting CPU Test program" << endl;
// loop for a long time

while (reps < 3000.0)
{
sleep(1);
}
cout << "average CPU frequency = " << freq_sum << endl;
cout << "reps = " << reps << endl;
cout << "Min = " << freq_min << " Max = " << freq_max << endl;
cout << "number of low = " << num_too_low << endl;
return 0;
}

Compiled the above code with "g++ -o test test.cpp"
Run the above code with "./test"

Observations:
SUSE Version AVG. Frequency AVG. REPS
Suse 9.3 999.xxx to 990.xxx reps > 1
(on average)
Suse 10.2 999.xxx to 998.xxx reps (1
- 1.001)
Suse 10.3 1000.xxx to 912.xxx reps (1 - 1.090)
Suse 11.1 0 to 324263.xxx reps
(-2e-0.6 upto 0.005112)

Suse 11.1 - Options:

- Turn off ACPI in options when booting with clock=tsc | clock=pit

Observations for suse 11.1 with options acpi=off and clock=tsc |
clock=pit

SUSE Version AVG. Frequency AVG. REPS
Suse 11.1 710.xxx to 999.xxx reps
(1.37xx to 1.0002)

Hardware used for Suse 11.1 - HP Pavilion Slimline s3821uk Desktop PC
(NQ808AA) specifications - HP Home & Home Office products
http://h10010.www1.hp.com/wwpc/uk/en/ho/WF10a/12454-12454-3329740-64546-
64546-3884669.html?jumpid=in_r2515_uk/en/hho/ipg/psc404redirect-ot-xx-xx
-/chev/

While testing no other application/s were running.

Question:

* Is my c++ code correct?
* Am I using the correct way to get the clock ticks or is there more
reliable tchnique avaliable to do this?
* Is that a problem with new Kernel if so is it a known issue ?
* Do I need to modify the Kernel to obtain regular and stable clock tick
at 1000 Hz ?
* Do I have to upgrade the Kernel ?
* Would be great, if pointed to the right direction for solution (e.g.
another forum) if no solution at hand.

Thanks

Subhan

********************************************************************
This email and any attachments are confidential to the intended
recipient and may also be privileged. If you are not the intended
recipient please delete it from your system and notify the sender.
You should not copy it or use it for any purpose nor disclose or
distribute its contents to any other person.
********************************************************************

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel"
in the body of a message to majordomo [at] vger More majordomo
info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel"
in the body of a message to majordomo [at] vger More majordomo
info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo [at] vger
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

czoccolo at gmail

Nov 24, 2009, 6:47 AM

Post #6 of 6 (291 views)
Permalink

Re: Kernel 2.6.27.7-9 for Suse 11.1 help required with CPU Clock freq/speed/ticks [In reply to]

On Thu, Nov 19, 2009 at 1:32 PM, Ahmed, Subhan (UK)
<Subhan.Ahmed [at] baesystems> wrote:
> Hi All,
>
> I know this is not email list for programming questions but it relates
> to Kernel as well, in fact relying on kernel. Could someone please
> through a light or guide me to the right direction.
>
>
> Problem Statement: High CPU clock speed/freq
> Requirement: Obtain a stable CPU clock ticks/speed/freq on
> Suse 11.1 with kernel 2.6.27.7-9
> Questions: Please refer to the bottom of this page
> Artifacts in Use:
> -----------------------------------
> OS: Suse 11.1
> GCC Version: 4.3.2 (Suse Linux) [gcc_4_3-brach revision
> 141291]
> Kernel: 2.6.27.7-9
> Kernel Mods:
> * Un-check the Tickless option
> * Timer Frequency - 1000Hz
> * Preempt kernel
>
> Others 1
> -----------
> OS: Suse 10.2
> GCC Version: 4.1.2 20061115 (prerelease)(SUSE Linux)
> Kernel: 2.6.18.2-34-default
> Kernel Mods:
> * Preemptible Kernel
> (Low-Latency Desktop) (NEW)
> * Preempt The Big Kernel Lock
> (NEW)
> * Timer frequency (NEW) - 1000
> Hz (NEW)
>
> Others 2
> -----------
> OS: Suse 9.3
> GCC Version: 3.3.5 20050117 (prerelease)(SUSE Linux)
> Kernel 2.6.11.4-20a-default
> Kernel Mods: None
>
> I executed the following c++ code on the above stated builds
>
> CODE - file name test.cpp
> #include <signal.h>
> #include <sys/time.h>
> #include <iostream>
> #include <cstdlib>
>
>
> using namespace std;
>
> long long int counter = 0;
> struct timeval last_time;
> struct timeval curr_time;
> double dif = 0.0;
> double freq_sum = 0.0;
> double reps = 0.0;
> double freq_min = 99999.0;
> double freq_max = 0.0;
> long long int num_too_low = 0;
>
> void time_check(int data)
> {
> // work out the frequecy of the SIGALRMs
> ++counter;
> if (counter >= 1000)
> {
>
> // need to work out time since last 1000 ticks
> gettimeofday(&curr_time, NULL);
> dif = ((curr_time.tv_usec + curr_time.tv_sec * 1000000)
> - (last_time.tv_usec + last_time.tv_sec * 1000000));
> double freq = (counter / dif) * 1000000;
>
> freq_sum = ((freq_sum * reps) + freq) / (reps + 1) ;
>
> ++reps;
> cout << "Frequency = " << freq << " reps= " << dif / 1000000 <<
> endl;
> if (freq_min > freq) freq_min = freq;
> if (freq_max < freq) freq_max = freq;
> if (freq < 950)
> ++num_too_low;
> last_time = curr_time;
> counter = 0;
> }
> }
>
> int main (int argc, char * argv[])
> {
> cout << "go" /* << "\a \a \a" */ << endl;
>
> int res;
> gettimeofday(&last_time, NULL);
> struct sigaction action;
>
> struct itimerval timer_value;
>
> timer_value.it_value.tv_sec = 0;
> timer_value.it_value.tv_usec = 1;
> timer_value.it_interval.tv_sec = 0;
> timer_value.it_interval.tv_usec = 1;
>
> action.sa_handler = time_check;
> action.sa_flags = SA_NOMASK;
> sigemptyset(&action.sa_mask);
>
> sigaction( SIGALRM, &action, NULL);
> res = setitimer( ITIMER_REAL, &timer_value, NULL );
> if (res == -1)
> cout << "error in setitimer" << endl;
>
> cout << "Starting CPU Test program" << endl;
> // loop for a long time
>
> while (reps < 3000.0)
> {
> sleep(1);
> }
> cout << "average CPU frequency = " << freq_sum << endl;
> cout << "reps = " << reps << endl;
> cout << "Min = " << freq_min << " Max = " << freq_max << endl;
> cout << "number of low = " << num_too_low << endl;
> return 0;
> }
>
> Compiled the above code with "g++ -o test test.cpp"
> Run the above code with "./test"
>
> Observations:
> SUSE Version AVG. Frequency AVG. REPS
> Suse 9.3 999.xxx to 990.xxx reps > 1
> (on average)
> Suse 10.2 999.xxx to 998.xxx reps (1
> - 1.001)
> Suse 10.3 1000.xxx to 912.xxx reps (1 - 1.090)
> Suse 11.1 0 to 324263.xxx reps
> (-2e-0.6 upto 0.005112)
>
> Suse 11.1 - Options:
>
> - Turn off ACPI in options when booting with clock=tsc | clock=pit
>
> Observations for suse 11.1 with options acpi=off and clock=tsc |
> clock=pit
>
> SUSE Version AVG. Frequency AVG. REPS
> Suse 11.1 710.xxx to 999.xxx reps
> (1.37xx to 1.0002)
>
> Hardware used for Suse 11.1 - HP Pavilion Slimline s3821uk Desktop PC
> (NQ808AA) specifications - HP Home & Home Office products
> http://h10010.www1.hp.com/wwpc/uk/en/ho/WF10a/12454-12454-3329740-64546-
> 64546-3884669.html?jumpid=in_r2515_uk/en/hho/ipg/psc404redirect-ot-xx-xx
> -/chev/
>
> While testing no other application/s were running.
>
> Question:
>
> * Is my c++ code correct?
No. It segfaults on my machine.
BTW, it doesn't measure the clock ticks.
It measures the maximum frequency at which the kernel can fire the
sigalarm, if the machine is fast enough running the time_check.
If the machine is not fast enough, it will print random values (due to
time_check being not reentrant) or segfault.

> * Am I using the correct way to get the clock ticks or is there more
> reliable tchnique avaliable to do this?
Clock ticks do not matter to userspace with newer kernels, since the
high resolution timers can give you a flow of interrupts at 1us
delays.
> * Is that a problem with new Kernel if so is it a known issue ?
No, it is an improvement.
> * Do I need to modify the Kernel to obtain regular and stable clock tick
> at 1000 Hz ?
You can probably disable the high resolution timers, but maybe
changing the way you look at the problem you are solving would be
better. Why are you trying to measure clock ticks? What is the real
problem you want to solve?

> * Do I have to upgrade the Kernel ?
> * Would be great, if pointed to the right direction for solution (e.g.
> another forum) if no solution at hand.
>
> Thanks

Thanks,
Corrado

--
__________________________________________________________________________

dott. Corrado Zoccolo mailto:czoccolo [at] gmail
PhD - Department of Computer Science - University of Pisa, Italy
--------------------------------------------------------------------------
The self-confidence of a warrior is not the self-confidence of the average
man. The average man seeks certainty in the eyes of the onlooker and calls
that self-confidence. The warrior seeks impeccability in his own eyes and
calls that humbleness.
Tales of Power - C. Castaneda
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo [at] vger
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

Index | Next | Previous | View Threaded

Interested in having your list archived? Contact Gossamer Threads