linux-toradex.git/kernel/time.c, branch v2.6.23.12

Cleanup non-arch xtime uses, use get_seconds() or current_kernel_time().

2007-07-25T17:09:20+00:00

This avoids use of the kernel-internal "xtime" variable directly outside
of the actual time-related functions.  Instead, use the helper functions
that we already have available to us.

This doesn't actually change any behaviour, but this will allow us to
fix the fact that "xtime" isn't updated very often with CONFIG_NO_HZ
(because much of the realtime information is maintained as separate
offsets to 'xtime'), which has caused interfaces that use xtime directly
to get a time that is out of sync with the real-time clock by up to a
third of a second or so.

Signed-off-by: John Stultz 
Cc: Ingo Molnar 
Cc: Thomas Gleixner 
Signed-off-by: Linus Torvalds

Revert "sys_time() speedup"

2007-07-20T20:32:46+00:00

This basically reverts commit 4e44f3497d41db4c3b9051c61410dee8ae4fb49c,
while waiting for it to be re-done more completely.  There are cases of
people mixing "time()" with higher-resolution time sources, and we need
to take the nanosecond offsets into account.

Ingo has a patch that does that, but it's still under some discussion.
In the meantime, just revert back to the old simple situation of just
doing the whole exact timesource calculations.

But rather than using do_gettimeofday(), use the internal nanosecond
resolution getnstimeofday(), which at least avoids one unnecessary
conversion (since we really don't care about whether the fractional
seconds are nanoseconds or microseconds - we'll just throw them away).

Signed-off-by: Linus Torvalds

[IA64] remove time interpolator

2007-07-20T18:23:02+00:00

Remove time_interpolator code (This is generic code, but
only user was ia64.  It has been superseded by the
CONFIG_GENERIC_TIME code).

Signed-off-by: Bob Picco 
Signed-off-by: John Stultz 
Signed-off-by: Peter Keilty 
Signed-off-by: Tony Luck

sys_time() speedup

2007-07-16T16:05:48+00:00

Improve performance of sys_time().  sys_time() returns time in seconds, but
it does so by calling do_gettimeofday() and then returning the tv_sec
portion of the GTOD time.  But the data structure "xtime", which is updated
by every timer/scheduler tick, already offers HZ granularity time.

The patch improves the sysbench OLTP macrobenchmark significantly:

2.6.22-rc6:

#threads
   1:        transactions:                        3733   (373.21 per sec.)
   2:        transactions:                        6676   (667.46 per sec.)
   3:        transactions:                        6957   (695.50 per sec.)
   4:        transactions:                        7055   (705.48 per sec.)
   5:        transactions:                        6596   (659.33 per sec.)

2.6.22-rc6 + sys_time.patch:

   1:        transactions:                        4005   (400.47 per sec.)
   2:        transactions:                        7379   (737.77 per sec.)
   3:        transactions:                        7347   (734.49 per sec.)
   4:        transactions:                        7468   (746.65 per sec.)
   5:        transactions:                        7428   (742.47 per sec.)

Mixed API uses of gettimeofday() and time() are guaranteed to be coherent
via the use of a at-most-once-per-second slowpath that updates xtime.

[akpm@linux-foundation.org: build fixes]
Signed-off-by: Ingo Molnar 
Cc: John Stultz 
Cc: Thomas Gleixner 
Cc: Roman Zippel 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

header cleaning: don't include smp_lock.h when not used

2007-05-08T18:15:07+00:00

Remove includes of  where it is not used/needed.
Suggested by Al Viro.

Builds cleanly on x86_64, i386, alpha, ia64, powerpc, sparc,
sparc64, and arm (all 59 defconfigs).

Signed-off-by: Randy Dunlap 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Optimize timespec_trunc()

2007-05-08T18:15:01+00:00

The first thing done by timespec_trunc() is :

  if (gran <= jiffies_to_usecs(1) * 1000)

This should really be a test against a constant known at compile time.

Alas, it isnt. jiffies_to_usec() was unilined so C compiler emits a function
call and a multiply to compute : a CONSTANT.

mov    $0x1,%edi
mov    %rbx,0xffffffffffffffe8(%rbp)
mov    %r12,0xfffffffffffffff0(%rbp)
mov    %edx,%ebx
mov    %rsi,0xffffffffffffffc8(%rbp)
mov    %rsi,%r12
callq  ffffffff80232010 
imul   $0x3e8,%eax,%eax
cmp    %ebx,%eax

This patch reorders kernel/time.c a bit so that jiffies_to_usecs() is defined
before timespec_trunc() so that compiler now generates :

cmp    $0x3d0900,%edx  (HZ=250 on my machine)

This gives a better code (timespec_trunc() becoming a leaf function), and
shorter kernel size as well.

Signed-off-by: Eric Dumazet 
Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Cc: john stultz 
Cc: Roman Zippel 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[TCP] tcp_probe: improvements for net-2.6.22

2007-04-26T05:28:10+00:00

Change tcp_probe to use ktime (needed to add one export).
Add option to only get events when cwnd changes - from Doug Leith

Signed-off-by: Stephen Hemminger 
Signed-off-by: David S. Miller

[NET]: convert network timestamps to ktime_t

2007-04-26T05:23:34+00:00

We currently use a special structure (struct skb_timeval) and plain
'struct timeval' to store packet timestamps in sk_buffs and struct
sock.

This has some drawbacks :
- Fixed resolution of micro second.
- Waste of space on 64bit platforms where sizeof(struct timeval)=16

I suggest using ktime_t that is a nice abstraction of high resolution
time services, currently capable of nanosecond resolution.

As sizeof(ktime_t) is 8 bytes, using ktime_t in 'struct sock' permits
a 8 byte shrink of this structure on 64bit architectures. Some other
structures also benefit from this size reduction (struct ipq in
ipv4/ip_fragment.c, struct frag_queue in ipv6/reassembly.c, ...)

Once this ktime infrastructure adopted, we can more easily provide
nanosecond resolution on top of it. (ioctl SIOCGSTAMPNS and/or
SO_TIMESTAMPNS/SCM_TIMESTAMPNS)

Note : this patch includes a bug correction in
compat_sock_get_timestamp() where a "err = 0;" was missing (so this
syscall returned -ENOENT instead of 0)

Signed-off-by: Eric Dumazet 
CC: Stephen Hemminger 
CC: John find 
Signed-off-by: David S. Miller

[PATCH] kernel/time.c: add missing symbol exports

2007-04-05T00:35:53+00:00

This patch adds 2 missing symbol exports: jiffies_to_timeval() and
timeval_to_jiffies().  The (not yet merged) dm-raid4-5 module will need
them, and they used to be indirectly exported by virtue of being inline
functions.

Commit 8b9365d753d9870bb6451504c13570b81923228f ("[PATCH] Uninline
jiffies.h functions") uninlined them, and thus modules now need them
explicitly exported to use them.

Signed-off-by: Thomas Bittermann 
Acked-by: Andrew Morton 
Acked-by: Ingo Molnar 
Acked-by: Thomas Gleixner 
Acked-by: john stultz 
Signed-off-by: Linus Torvalds

[PATCH] Fix multiple conversion bugs in msecs_to_jiffies

2007-02-16T16:13:56+00:00

Fix multiple conversion bugs in msecs_to_jiffies().

The main problem is that this condition:

	if (m > jiffies_to_msecs(MAX_JIFFY_OFFSET))

overflows if HZ is smaller than 1000!

This change is user-visible: for HZ=250 SUS-compliant poll()-timeout
value of -20 is mistakenly converted to 'immediate timeout'.

(The new dyntick code also triggered this, that's how we noticed.)

Signed-off-by: Ingo Molnar 
Signed-off-by: Thomas Gleixner 
Cc: john stultz 
Cc: Roman Zippel 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds