[Minios-devel] [UNIKRAFT PATCH v4] plat/*: Make timer interrupt frequency selectable

[Florian Schmidt <florian.schmidt@xxxxxxxxx>]

Add new configuration options for choosing a timer interrupt frequency.
The configured frequency is converted to the timer tick length which can
be of use for other modules (e.g., preemptive schedulers).

Previously, the tick was 100 Hz on KVM and 1000 Hz on Xen. The default
value is now 100 Hz across both platforms.

Signed-off-by: Costin Lupu <costin.lupu@xxxxxxxxx>
Signed-off-by: Florian Schmidt <florian.schmidt@xxxxxxxxx>
---
 include/uk/arch/time.h            |  2 ++
 include/uk/plat/time.h            |  4 ++++
 plat/Config.uk                    |  7 +++++++
 plat/kvm/x86/tscclock.c           | 10 ++++------
 plat/linuxu/include/linuxu/time.h |  3 ++-
 plat/linuxu/time.c                |  2 --
 plat/xen/x86/arch_time.c          |  2 +-
 7 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/include/uk/arch/time.h b/include/uk/arch/time.h
index 262fd3b..5a5aa22 100644
--- a/include/uk/arch/time.h
+++ b/include/uk/arch/time.h
@@ -57,6 +57,8 @@ typedef __s64 __snsec;
 #define __SNSEC_MAX (__S64_MAX)
 #define __SNSEC_MIN (__S64_MIN)
 
+#define NSEC_PER_SEC         1000000000ULL
+
 #define ukarch_time_nsec_to_sec(ns)      ((ns) / 1000000000ULL)
 #define ukarch_time_nsec_to_msec(ns)     ((ns) / 1000000ULL)
 #define ukarch_time_nsec_to_usec(ns)     ((ns) / 1000UL)
diff --git a/include/uk/plat/time.h b/include/uk/plat/time.h
index 202e0f9..d38e3c6 100644
--- a/include/uk/plat/time.h
+++ b/include/uk/plat/time.h
@@ -47,6 +47,10 @@ void ukplat_time_fini(void);
 
 __nsec ukplat_monotonic_clock(void);
 
+/* Time tick length */
+#define UKPLAT_TIME_TICK_NSEC  (NSEC_PER_SEC / CONFIG_HZ)
+#define UKPLAT_TIME_TICK_MSEC  ukarch_time_nsec_to_msec(UKPLAT_TIME_TICK_NSEC)
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/plat/Config.uk b/plat/Config.uk
index b776c45..ae96487 100644
--- a/plat/Config.uk
+++ b/plat/Config.uk
@@ -17,3 +17,10 @@ config EARLY_PRINT_PL011_UART_ADDR
                Pl011 serial address used by early debug console.
 
 endmenu
+
+config HZ
+       int
+       prompt "Timer frequency (Hz)"
+       default 100
+       help
+               Configure the timer interrupt frequency.
diff --git a/plat/kvm/x86/tscclock.c b/plat/kvm/x86/tscclock.c
index f3fa55a..d3cdb16 100644
--- a/plat/kvm/x86/tscclock.c
+++ b/plat/kvm/x86/tscclock.c
@@ -60,8 +60,6 @@
 #include <uk/assert.h>
 #include <uk/bitops.h>
 
-#define NSEC_PER_SEC         1000000000ULL
-
 #define TIMER_CNTR           0x40
 #define TIMER_MODE           0x43
 #define TIMER_SEL0           0x00
@@ -131,7 +129,7 @@ static void i8254_delay(unsigned int n)
 {
        unsigned int cur_tick, initial_tick;
        int remaining;
-       const unsigned long timer_rval = TIMER_HZ / 100;
+       const unsigned long timer_rval = TIMER_HZ / CONFIG_HZ;
 
        initial_tick = i8254_gettick();
 
@@ -211,10 +209,10 @@ int tscclock_init(void)
 {
        __u64 tsc_freq, rtc_boot;
 
-       /* Initialise i8254 timer channel 0 to mode 2 at 100 Hz */
+       /* Initialise i8254 timer channel 0 to mode 2 at CONFIG_HZ frequency */
        outb(TIMER_MODE, TIMER_SEL0 | TIMER_RATEGEN | TIMER_16BIT);
-       outb(TIMER_CNTR, (TIMER_HZ / 100) & 0xff);
-       outb(TIMER_CNTR, (TIMER_HZ / 100) >> 8);
+       outb(TIMER_CNTR, (TIMER_HZ / CONFIG_HZ) & 0xff);
+       outb(TIMER_CNTR, (TIMER_HZ / CONFIG_HZ) >> 8);
 
        /*
         * Read RTC "time at boot". This must be done just before tsc_base is
diff --git a/plat/linuxu/include/linuxu/time.h 
b/plat/linuxu/include/linuxu/time.h
index 2df881e..c1a875a 100644
--- a/plat/linuxu/include/linuxu/time.h
+++ b/plat/linuxu/include/linuxu/time.h
@@ -35,9 +35,10 @@
 #ifndef __LINUXU_TIME_H__
 #define __LINUXU_TIME_H__
 
+#include <uk/plat/time.h>
 #include <linuxu/signal.h>
 
-#define TIMER_INTVAL_MSEC    10
+#define TIMER_INTVAL_NSEC    UKPLAT_TIME_TICK_NSEC
 #define TIMER_SIGNUM         SIGALRM
 
 
diff --git a/plat/linuxu/time.c b/plat/linuxu/time.c
index ead07f5..13439ad 100644
--- a/plat/linuxu/time.c
+++ b/plat/linuxu/time.c
@@ -40,8 +40,6 @@
 #include <linuxu/syscall.h>
 #include <linuxu/time.h>
 
-#define TIMER_INTVAL_NSEC    ukarch_time_msec_to_nsec(TIMER_INTVAL_MSEC)
-
 static k_timer_t timerid;
 
 
diff --git a/plat/xen/x86/arch_time.c b/plat/xen/x86/arch_time.c
index 95d7b10..a4b77b9 100644
--- a/plat/xen/x86/arch_time.c
+++ b/plat/xen/x86/arch_time.c
@@ -233,7 +233,7 @@ void time_block_until(__snsec until)
 static void timer_handler(evtchn_port_t ev __unused,
                struct __regs *regs __unused, void *ign __unused)
 {
-       __nsec until = ukplat_monotonic_clock() + ukarch_time_msec_to_nsec(1);
+       __nsec until = ukplat_monotonic_clock() + UKPLAT_TIME_TICK_NSEC;
 
        HYPERVISOR_set_timer_op(until);
 }
-- 
2.19.1


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