linux-toradex.git/arch/ia64/kernel/fsys.S, branch v3.0.64

[IA64] Optimize ticket spinlocks in fsys_rt_sigprocmask

2010-09-15T22:35:48+00:00

Tony's fix (f574c843191728d9407b766a027f779dcd27b272) has a small bug,
it incorrectly uses "r3" as a scratch register in the first of the two
unlock paths ... it is also inefficient.  Optimize the fast path again.

Signed-off-by: Petr Tesarik 
Signed-off-by: Tony Luck

[IA64] fix siglock

2010-09-09T22:16:56+00:00

When ia64 converted to using ticket locks, an inline implementation
of trylock/unlock in fsys.S was missed.  This was not noticed because
in most circumstances it simply resulted in using the slow path because
the siglock was apparently not available (under old spinlock rules).

Problems occur when the ticket spinlock has value 0x0 (when first
initialised, or when it wraps around). At this point the fsys.S
code acquires the lock (changing the 0x0 to 0x1. If another process
attempts to get the lock at this point, it will change the value from
0x1 to 0x2 (using new ticket lock rules). Then the fsys.S code will
free the lock using old spinlock rules by writing 0x0 to it. From
here a variety of bad things can happen.

Signed-off-by: Tony Luck

ia64/pv_ops: paravirtualize mov = ar.itc.

2009-03-26T17:50:22+00:00

paravirtualize mov reg = ar.itc.

Signed-off-by: Isaku Yamahata 
Signed-off-by: Tony Luck

ia64/pv_ops: paravirtualize fsys.S.

2009-03-26T17:50:01+00:00

paravirtualize fsys.S.

Signed-off-by: Isaku Yamahata 
Signed-off-by: Tony Luck

ia64/pv_ops: add hooks to paravirtualize fsyscall implementation.

2009-03-26T17:48:33+00:00

Add two hooks, paravirt_get_fsyscall_table() and
paravirt_get_fsys_bubble_doen() to paravirtualize fsyscall implementation.
This patch just add the hooks fsyscall and don't paravirtualize it.

Signed-off-by: Isaku Yamahata 
Signed-off-by: Tony Luck

Pull miscellaneous into release branch

2008-04-17T17:14:51+00:00

Conflicts:

	arch/ia64/kernel/mca.c

Pull virt-cpu-accounting into release branch

2008-04-17T17:12:27+00:00

[IA64] fix getpid and set_tid_address fast system calls for pid namespaces

2008-04-09T17:33:36+00:00

The sys_getpid() and sys_set_tid_address() behavior changed from

	return current->tgid

to

	struct pid *pid;
	pid = current->pids[PIDTYPE_PID].pid;
	return pid->numbers[pid->level].nr;

But the fast system calls on ia64 still operate the old way.  Patch them
appropriately to let ia64 work with pid namespaces.  Besides, this is one more
step in deprecating of pid and tgid on task_struct.

The fsys_getppid() is to be patched as well, but its logic is much
more complex now, so I will make it later.

One thing I'm not 100% sure is the trick with the IA64_UPID_SHIFT.  On order
to access the pid->level's element of an array I have to perform the following
calculations

	pid + sizeof(struct upid) * pid->level

The problem is that ia64 can only multiply float point registers, while all
the offsets I have in code are in rXX ones.  Fortunately, the sizeof(struct
upid) is 32 bytes on ia64 (and is very unlikely to ever change), so the
calculations get simpler:

	pid + pid->level << 5

So, I introduce the IA64_UPID_SHIFT and use the shl instruction.  I also
looked at how gcc compiles the similar place and found that it makes it with
shift as well.  Is this OK to do so?

Tested with ski emulator with 2.6.24 kernel, but fits 2.6.25-rc4 and
2.6.25-rc4-mm1 as well.

Signed-off-by: Pavel Emelyanov 
Cc: David Mosberger-Tang 
Cc: Hidetoshi Seto 
Cc: Fenghua Yu 
Cc: Amy Griffis 
Signed-off-by: Andrew Morton 
Signed-off-by: Tony Luck

[IA64] cleanup and improve fsys_gettimeofday

2008-03-10T23:35:47+00:00

This patch does:

 - Remove outdated comments (which someday I marked with "?").
 - Reassemble instructions to fit them in fewer bundles.
 - If McKinley Errata 9 workaround is not needed, the workaround
   bundles will be patched out with NOPs. However it also not
   needed to have a totally NOP bundle (nop * 3) before branch.

As a result, this makes the code path 3 (or 2) bundles shorter
(and remove 1 unnecessary stop bit). It seems to be 1% faster.

(10sec loop test, with nojitter @ Madison 1.5GHz x 4)
Before:
 CPU  0:  0.14 (usecs) (0 errors / 69598875 iterations)
 CPU  1:  0.14 (usecs) (0 errors / 69630721 iterations)
 CPU  2:  0.14 (usecs) (0 errors / 69607850 iterations)
 CPU  3:  0.14 (usecs) (0 errors / 69619832 iterations)

After:
 CPU  0:  0.14 (usecs) (0 errors / 70257728 iterations)
 CPU  1:  0.14 (usecs) (0 errors / 70309498 iterations)
 CPU  2:  0.14 (usecs) (0 errors / 70280639 iterations)
 CPU  3:  0.14 (usecs) (0 errors / 70260682 iterations)

Signed-off-by: Hidetoshi Seto 
Signed-off-by: Tony Luck

[IA64] VIRT_CPU_ACCOUNTING (accurate cpu time accounting)

2008-02-20T20:55:37+00:00

This patch implements VIRT_CPU_ACCOUNTING for ia64,
which enable us to use more accurate cpu time accounting.

The VIRT_CPU_ACCOUNTING is an item of kernel config, which s390
and powerpc arch have.  By turning this config on, these archs
change the mechanism of cpu time accounting from tick-sampling
based one to state-transition based one.

The state-transition based accounting is done by checking time
(cycle counter in processor) at every state-transition point,
such as entrance/exit of kernel, interrupt, softirq etc.
The difference between point to point is the actual time consumed
during in the state. There is no doubt about that this value is
more accurate than that of tick-sampling based accounting.

Signed-off-by: Hidetoshi Seto 
Signed-off-by: Tony Luck