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| author | Haiyang Zhang <haiyangz@microsoft.com> | 2010-05-11 15:11:24 (GMT) |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2010-05-11 22:31:52 (GMT) |
| commit | e9ec36030cca2549cb656d94347dafecfcf218f6 (patch) | |
| tree | 93fc1ac781dfa7ae63a8e7d2f4b0f46b81cc5f05 /drivers | |
| parent | ce7f6389790f24e07e7e32518c798451e799a830 (diff) | |
| download | linux-e9ec36030cca2549cb656d94347dafecfcf218f6.tar.xz | |
staging: hv: Optimize adj_guesttime function and add more detailed comments
Credits go to Joe Perches <joe@perches.com> for suggesting the changes.
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Hank Janssen <hjanssen@microsoft.com>
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers')
| -rw-r--r-- | 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..db45d97a 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; } /* |