From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:51210) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VAOnF-0004c5-SB for qemu-devel@nongnu.org; Fri, 16 Aug 2013 14:30:41 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VAOnC-0008KY-PP for qemu-devel@nongnu.org; Fri, 16 Aug 2013 14:30:37 -0400 Received: from mail.avalus.com ([2001:41c8:10:1dd::10]:47662) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VAOnC-0008KB-D4 for qemu-devel@nongnu.org; Fri, 16 Aug 2013 14:30:34 -0400 From: Alex Bligh Date: Fri, 16 Aug 2013 19:29:44 +0100 Message-Id: <1376677812-9448-4-git-send-email-alex@alex.org.uk> In-Reply-To: <1376677812-9448-1-git-send-email-alex@alex.org.uk> References: <1376677812-9448-1-git-send-email-alex@alex.org.uk> Subject: [Qemu-devel] [PATCHv12 03/31] aio / timers: add qemu-timer.c utility functions List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Kevin Wolf , Anthony Liguori , Alex Bligh , Jan Kiszka , liu ping fan , Stefan Hajnoczi , Paolo Bonzini , MORITA Kazutaka , rth@twiddle.net Add utility functions to qemu-timer.c for nanosecond timing. Add qemu_clock_deadline_ns to calculate deadlines to nanosecond accuracy. Add utility function qemu_soonest_timeout to calculate soonest deadline. Add qemu_timeout_ns_to_ms to convert a timeout in nanoseconds back to milliseconds for when ppoll is not used. Signed-off-by: Alex Bligh --- include/qemu/timer.h | 42 ++++++++++++++++++++++++++++++++++++++++++ qemu-timer.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 92 insertions(+) diff --git a/include/qemu/timer.h b/include/qemu/timer.h index da43cbe..e0a51a1 100644 --- a/include/qemu/timer.h +++ b/include/qemu/timer.h @@ -40,6 +40,29 @@ int64_t qemu_get_clock_ns(QEMUClock *clock); int64_t qemu_clock_has_timers(QEMUClock *clock); int64_t qemu_clock_expired(QEMUClock *clock); int64_t qemu_clock_deadline(QEMUClock *clock); + +/** + * qemu_clock_deadline_ns: + * @clock: the clock to operate on + * + * Calculate the timeout of the earliest expiring timer + * in nanoseconds, or -1 if no timer is set to expire. + * + * Returns: time until expiry in nanoseconds or -1 + */ +int64_t qemu_clock_deadline_ns(QEMUClock *clock); + +/** + * qemu_timeout_ns_to_ms: + * @ns: nanosecond timeout value + * + * Convert a nanosecond timeout value (or -1) to + * a millisecond value (or -1), always rounding up. + * + * Returns: millisecond timeout value + */ +int qemu_timeout_ns_to_ms(int64_t ns); + void qemu_clock_enable(QEMUClock *clock, bool enabled); void qemu_clock_warp(QEMUClock *clock); @@ -67,6 +90,25 @@ int64_t cpu_get_ticks(void); void cpu_enable_ticks(void); void cpu_disable_ticks(void); +/** + * qemu_soonest_timeout: + * @timeout1: first timeout in nanoseconds (or -1 for infinite) + * @timeout2: second timeout in nanoseconds (or -1 for infinite) + * + * Calculates the soonest of two timeout values. -1 means infinite, which + * is later than any other value. + * + * Returns: soonest timeout value in nanoseconds (or -1 for infinite) + */ +static inline int64_t qemu_soonest_timeout(int64_t timeout1, int64_t timeout2) +{ + /* we can abuse the fact that -1 (which means infinite) is a maximal + * value when cast to unsigned. As this is disgusting, it's kept in + * one inline function. + */ + return ((uint64_t) timeout1 < (uint64_t) timeout2) ? timeout1 : timeout2; +} + static inline QEMUTimer *qemu_new_timer_ns(QEMUClock *clock, QEMUTimerCB *cb, void *opaque) { diff --git a/qemu-timer.c b/qemu-timer.c index 4117add..df8f12b 100644 --- a/qemu-timer.c +++ b/qemu-timer.c @@ -273,6 +273,56 @@ int64_t qemu_clock_deadline(QEMUClock *clock) return delta; } +/* + * As above, but return -1 for no deadline, and do not cap to 2^32 + * as we know the result is always positive. + */ + +int64_t qemu_clock_deadline_ns(QEMUClock *clock) +{ + int64_t delta; + + if (!clock->enabled || !clock->active_timers) { + return -1; + } + + delta = clock->active_timers->expire_time - qemu_get_clock_ns(clock); + + if (delta <= 0) { + return 0; + } + + return delta; +} + +/* Transition function to convert a nanosecond timeout to ms + * This is used where a system does not support ppoll + */ +int qemu_timeout_ns_to_ms(int64_t ns) +{ + int64_t ms; + if (ns < 0) { + return -1; + } + + if (!ns) { + return 0; + } + + /* Always round up, because it's better to wait too long than to wait too + * little and effectively busy-wait + */ + ms = (ns + SCALE_MS - 1) / SCALE_MS; + + /* To avoid overflow problems, limit this to 2^31, i.e. approx 25 days */ + if (ms > (int64_t) INT32_MAX) { + ms = INT32_MAX; + } + + return (int) ms; +} + + QEMUTimer *qemu_new_timer(QEMUClock *clock, int scale, QEMUTimerCB *cb, void *opaque) { -- 1.7.9.5