[PATCH 1/1] staging: hv: Optimize adj_guesttime function and add more detailed comments (Resubmit with some cleanups)
in [Kernel]
|
Prev: ALSA: hda: Use STAC_DELL_M6_BOTH quirk for Dell Studio 1558
Next: drm/i915: Add initial bits for VGA modesetting bringup on Sandybridge.
From: Haiyang Zhang on 11 May 2010 11:20 From: Haiyang Zhang <haiyangz(a)microsoft.com> Subject: Optimize adj_guesttime function and add more detailed comments Credits go to Joe Perches [joe(a)perches.com] for suggesting the changes. Cc: Greg Kroah-Hartman <gregkh(a)suse.de> Signed-off-by: Hank Janssen <hjanssen(a)microsoft.com> Signed-off-by: Haiyang Zhang <haiyangz(a)microsoft.com> --- drivers/staging/hv/hv_utils.c | 33 +++++++++++++++++++++++---------- 1 files changed, 23 insertions(+), 10 deletions(-) diff --git a/drivers/staging/hv/hv_utils.c b/drivers/staging/hv/hv_utils.c index 8f1d3ba..db45d97 100644 --- a/drivers/staging/hv/hv_utils.c +++ b/drivers/staging/hv/hv_utils.c @@ -106,31 +106,44 @@ static void shutdown_onchannelcallback(void *context) orderly_poweroff(false); } - /* - * Synchronize time with host after reboot, restore, etc. + * Set guest time to host UTC time. */ -static void adj_guesttime(u64 hosttime, u8 flags) +static inline void do_adj_guesttime(u64 hosttime) { s64 host_tns; struct timespec host_ts; - static s32 scnt = 50; host_tns = (hosttime - WLTIMEDELTA) * 100; host_ts = ns_to_timespec(host_tns); + do_settimeofday(&host_ts); +} + +/* + * Synchronize time with host after reboot, restore, etc. + * + * ICTIMESYNCFLAG_SYNC flag bit indicates reboot, restore events of the VM.. + * After reboot the flag ICTIMESYNCFLAG_SYNC is included in the first time + * message after the timesync channel is opened. Since the hv_utils module is + * loaded after hv_vmbus, the first message is usually missed. The other + * thing is, systime is automatically set to emulated hardware clock which may + * not be UTC time or in the same time zone. So, to override these effects, we + * use the first 50 time samples for initial system time setting. + */ +static inline void adj_guesttime(u64 hosttime, u8 flags) +{ + static s32 scnt = 50; + if ((flags & ICTIMESYNCFLAG_SYNC) != 0) { - do_settimeofday(&host_ts); + do_adj_guesttime(hosttime); return; } - if ((flags & ICTIMESYNCFLAG_SAMPLE) != 0 && - scnt > 0) { + if ((flags & ICTIMESYNCFLAG_SAMPLE) != 0 && scnt > 0) { scnt--; - do_settimeofday(&host_ts); + do_adj_guesttime(hosttime); } - - return; } /* -- 1.6.3.2 |