[v1,1/2] eal: add nanosleep based delay function
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Commit Message
Add a new rte_delay_us_sleep() function that uses nanosleep().
This function can be used by applications to not implement
their own nanosleep() based callback and by internal DPDK
code if CPU non-blocking delay needed.
Signed-off-by: Ilya Maximets <i.maximets@samsung.com>
---
lib/librte_eal/common/eal_common_timer.c | 19 +++++++
.../common/include/generic/rte_cycles.h | 11 ++++
lib/librte_eal/rte_eal_version.map | 1 +
test/test/autotest_data.py | 6 +++
test/test/meson.build | 1 +
test/test/test_cycles.c | 51 ++++++++++++++-----
6 files changed, 75 insertions(+), 14 deletions(-)
Comments
On Mon, 3 Sep 2018 17:47:42 +0300
Ilya Maximets <i.maximets@samsung.com> wrote:
>
> +void __rte_experimental
> +rte_delay_us_sleep(unsigned int us)
> +{
> + struct timespec wait[2];
> + int ind = 0;
> +
> + wait[0].tv_sec = 0;
> + if (us >= US_PER_S) {
> + wait[0].tv_sec = us / US_PER_S;
> + us -= wait[0].tv_sec * US_PER_S;
> + }
> + wait[0].tv_nsec = 1000 * us;
> +
> + while (nanosleep(&wait[ind], &wait[1 - ind]) == EINTR)
> + ind = 1 - ind;
> +}
> +
This seems like a complex/tricky way to handle the case where
nanosleep is interrupted. It needs a comment.
On 05.09.2018 16:10, Stephen Hemminger wrote:
> On Mon, 3 Sep 2018 17:47:42 +0300
> Ilya Maximets <i.maximets@samsung.com> wrote:
>
>>
>> +void __rte_experimental
>> +rte_delay_us_sleep(unsigned int us)
>> +{
>> + struct timespec wait[2];
>> + int ind = 0;
>> +
>> + wait[0].tv_sec = 0;
>> + if (us >= US_PER_S) {
>> + wait[0].tv_sec = us / US_PER_S;
>> + us -= wait[0].tv_sec * US_PER_S;
>> + }
>> + wait[0].tv_nsec = 1000 * us;
>> +
>> + while (nanosleep(&wait[ind], &wait[1 - ind]) == EINTR)
>> + ind = 1 - ind;
>> +}
>> +
>
> This seems like a complex/tricky way to handle the case where
> nanosleep is interrupted. It needs a comment.
OK. I can add some comment here.
Best regards, Ilya Maximets.
@@ -7,9 +7,11 @@
#include <unistd.h>
#include <inttypes.h>
#include <sys/types.h>
+#include <time.h>
#include <errno.h>
#include <rte_common.h>
+#include <rte_compat.h>
#include <rte_log.h>
#include <rte_cycles.h>
#include <rte_pause.h>
@@ -31,6 +33,23 @@ rte_delay_us_block(unsigned int us)
rte_pause();
}
+void __rte_experimental
+rte_delay_us_sleep(unsigned int us)
+{
+ struct timespec wait[2];
+ int ind = 0;
+
+ wait[0].tv_sec = 0;
+ if (us >= US_PER_S) {
+ wait[0].tv_sec = us / US_PER_S;
+ us -= wait[0].tv_sec * US_PER_S;
+ }
+ wait[0].tv_nsec = 1000 * us;
+
+ while (nanosleep(&wait[ind], &wait[1 - ind]) == EINTR)
+ ind = 1 - ind;
+}
+
uint64_t
rte_get_tsc_hz(void)
{
@@ -13,6 +13,7 @@
*/
#include <stdint.h>
+#include <rte_compat.h>
#include <rte_debug.h>
#include <rte_atomic.h>
@@ -157,6 +158,16 @@ rte_delay_ms(unsigned ms)
*/
void rte_delay_us_block(unsigned int us);
+/**
+ * Delay function that uses system sleep.
+ * Does not block the CPU core.
+ *
+ * @param us
+ * Number of microseconds to wait.
+ */
+void __rte_experimental
+rte_delay_us_sleep(unsigned int us);
+
/**
* Replace rte_delay_us with user defined function.
*
@@ -270,6 +270,7 @@ EXPERIMENTAL {
rte_class_register;
rte_class_unregister;
rte_ctrl_thread_create;
+ rte_delay_us_sleep;
rte_dev_event_callback_register;
rte_dev_event_callback_unregister;
rte_dev_event_monitor_start;
@@ -278,6 +278,12 @@
"Func": default_autotest,
"Report": None,
},
+ {
+ "Name": "Sleep delay",
+ "Command": "delay_us_sleep_autotest",
+ "Func": default_autotest,
+ "Report": None,
+ },
{
"Name": "Rawdev autotest",
"Command": "rawdev_autotest",
@@ -143,6 +143,7 @@ test_names = [
'cryptodev_dpaa_sec_autotest',
'cycles_autotest',
'debug_autotest',
+ 'delay_us_sleep_autotest',
'devargs_autotest',
'distributor_autotest',
'distributor_perf_autotest',
@@ -23,6 +23,30 @@
* of cycles is correct with regard to the frequency of the timer.
*/
+static int
+check_wait_one_second(void)
+{
+ uint64_t cycles, prev_cycles;
+ uint64_t hz = rte_get_timer_hz();
+ uint64_t max_inc = (hz / 100); /* 10 ms max between 2 reads */
+
+ /* check that waiting 1 second is precise */
+ prev_cycles = rte_get_timer_cycles();
+ rte_delay_us(1000000);
+ cycles = rte_get_timer_cycles();
+
+ if ((uint64_t)(cycles - prev_cycles) > (hz + max_inc)) {
+ printf("delay_us is not accurate: too long\n");
+ return -1;
+ }
+ if ((uint64_t)(cycles - prev_cycles) < (hz - max_inc)) {
+ printf("delay_us is not accurate: too short\n");
+ return -1;
+ }
+
+ return 0;
+}
+
static int
test_cycles(void)
{
@@ -43,24 +67,23 @@ test_cycles(void)
prev_cycles = cycles;
}
- /* check that waiting 1 second is precise */
- prev_cycles = rte_get_timer_cycles();
- rte_delay_us(1000000);
- cycles = rte_get_timer_cycles();
+ return check_wait_one_second();
+}
- if ((uint64_t)(cycles - prev_cycles) > (hz + max_inc)) {
- printf("delay_us is not accurate: too long\n");
- return -1;
- }
- if ((uint64_t)(cycles - prev_cycles) < (hz - max_inc)) {
- printf("delay_us is not accurate: too short\n");
- return -1;
- }
+REGISTER_TEST_COMMAND(cycles_autotest, test_cycles);
- return 0;
+/*
+ * One second precision test with rte_delay_us_sleep.
+ */
+
+static int
+test_delay_us_sleep(void)
+{
+ rte_delay_us_callback_register(rte_delay_us_sleep);
+ return check_wait_one_second();
}
-REGISTER_TEST_COMMAND(cycles_autotest, test_cycles);
+REGISTER_TEST_COMMAND(delay_us_sleep_autotest, test_delay_us_sleep);
/*
* rte_delay_us_callback test