trace: Use 64-bit timekeeping
Subsystems (2)
PATCH v4 1/1 trace: Use 64-bit timekeeping
The ring_buffer_producer uses 'struct timeval' to measure its start and end times. 'struct timeval' on 32-bit systems will have its tv_sec value overflow in year 2038 and beyond. This patch replaces struct timeval with 'ktime_t' which uses 64-bit representation for nanoseconds.
---
Changes in v4:
- Fix typo in commit message.
- Avoid typecast to 'long long' by defining RUN_TIME as '10ULL' instead of '10'.
Changes in v3:
- Use a more efficient way to compute condition for exiting loop.
- Fix variable naming - all caps is only for macros.
Changes in v2:
- Use ktime_t instead of timespec64 for efficiency reasons.
--- kernel/trace/ring_buffer_benchmark.c | 18 ++++++++---------- 1 file changed, 8 insertions(+), 10 deletions(-)
kernel/trace/ring_buffer_benchmark.c +8 -10
@@ -7,7 +7,7 @@#include <linux/completion.h> #include <linux/kthread.h> #include <linux/module.h> -#include <linux/time.h> +#include <linux/ktime.h> #include <asm/local.h> struct rb_page {
@@ -17,7 +17,7 @@ struct rb_page { };/* run time and sleep time in seconds */ -#define RUN_TIME 10 +#define RUN_TIME 10ULL#define SLEEP_TIME 10/* number of events for writer to wake up the reader */
@@ -212,8 +212,7 @@ static void ring_buffer_consumer(void)static void ring_buffer_producer (void ) { -struct timeval start_tv; -struct timeval end_tv; +ktime_t start_time, end_time, timeout;unsigned long long time;unsigned long long entries;unsigned long long overruns;
@@ -227,7 +226,8 @@ static void ring_buffer_producer(void)* make the system stall) */ trace_printk ("Starting ring buffer hammer\n" ); -do_gettimeofday (&start_tv); + start_time =ktime_get (); + timeout =ktime_add_ns (start_time,RUN_TIME *NSEC_PER_SEC ); do { struct ring_buffer_event *event; int *entry;
@@ -244,7 +244,7 @@ static void ring_buffer_producer(void)ring_buffer_unlock_commit (buffer, event); } } -do_gettimeofday (&end_tv); + end_time =ktime_get (); cnt++;if (consumer && !(cnt % wakeup_interval))
@@ -264,7 +264,7 @@ static void ring_buffer_producer(void)cond_resched ();#endif - }while (end_tv.tv_sec < (start_tv.tv_sec +RUN_TIME ) && !kill_test); + }while (ktime_before (end_time, timeout) && !kill_test);trace_printk ("End ring buffer hammer\n" );if (consumer) {
@@ -280,9 +280,7 @@ static void ring_buffer_producer(void)wait_for_completion (&read_done); } - time = end_tv.tv_sec - start_tv.tv_sec; - time *=USEC_PER_SEC ; - time += (long long )((long )end_tv.tv_usec - (long )start_tv.tv_usec); + time =ktime_us_delta (end_time, start_time); entries =ring_buffer_entries (buffer); overruns =ring_buffer_overruns (buffer);
Signature · 1 line
2.2.0.rc0.207.ga3a616c
Steven Rostedt
maintainerQuoted 6 lines · On Wed, 28 Jan 2015 19:46:11 +0530 Tina Ruchandani <[email protected]>…
The
ring_buffer_produceruses 'struct timeval' to measure its start and end times. 'struct timeval' on 32-bit systems will have itstv_secvalue overflow in year 2038 and beyond. This patch replaces struct timeval with 'ktime_t' which uses 64-bit representation for nanoseconds.
Quoted 8 lines
Suggested-by Arnd Bergmann <[email protected]>Suggested-by Steven Rostedt <[email protected]>Signed-off-by Tina Ruchandani <[email protected]>---
Changes in v4:
- Fix typo in commit message.
- Avoid typecast to 'long long' by definingRUN_TIMEas '10ULL' instead of '10'.
Although I have not tested this, this patch looks fine to me. Is this going to go through some cleanup tree or should I just pull it?
-- Steve
Quoted 5 lines
Changes in v3:
- Use a more efficient way to compute condition for exiting loop.
- Fix variable naming - all caps is only for macros.
Changes in v2:
- Usektime_tinstead of timespec64 for efficiency reasons.
Quoted 18 lines · On Wednesday 28 January 2015 09:53:49 Steven Rostedt wrote:
Quoted 6 lines · On Wed, 28 Jan 2015 19:46:11 +0530 Tina Ruchandani <[email protected]>…
The
ring_buffer_produceruses 'struct timeval' to measure its start and end times. 'struct timeval' on 32-bit systems will have itstv_secvalue overflow in year 2038 and beyond. This patch replaces struct timeval with 'ktime_t' which uses 64-bit representation for nanoseconds.Quoted 8 lines
Suggested-by Arnd Bergmann <[email protected]>Suggested-by Steven Rostedt <[email protected]>Signed-off-by Tina Ruchandani <[email protected]>---
Changes in v4:
- Fix typo in commit message.
- Avoid typecast to 'long long' by definingRUN_TIMEas '10ULL' instead of '10'.
Quoted 3 lines
Although I have not tested this, this patch looks fine to me. Is this going to go through some cleanup tree or should I just pull it?
Please apply it to your tree.
Arnd
Steven Rostedt
maintainerQuoted 1 line · On Wed, 28 Jan 2015 15:55:39 +0100 Arnd Bergmann <[email protected]> wrote:
Please apply it to your tree.
Will do.
Thanks,
-- Steve