Using get_cycles was unnecessary: check_tsc_warp() is not called
on TSC-less systems. Replace rdtsc_barrier(); get_cycles() with
rdtsc_ordered().
While we're at it, make the somewhat more dangerous change of
removing barrier_before_rdtsc after RDTSC in the TSC warp check
code. This should be okay, though -- the vDSO TSC code doesn't
have that barrier, so, if removing the barrier from the warp
check would cause us to detect a warp that we otherwise wouldn't
detect, then we have a genuine bug.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Huang Rui <ray.huang@amd.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Len Brown <lenb@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kvm ML <kvm@vger.kernel.org>
Link: http://lkml.kernel.org/r/387c4c3a75f875bcde6cd68cee013273a744f364.1434501121.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The former duplicate the functionalities of the latter but are
neither documented nor arch-independent.
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Benoit Cousson <bcousson@baylibre.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Jean Delvare <jdelvare@suse.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Drokin <oleg.drokin@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: http://lkml.kernel.org/r/1432645896-12588-9-git-send-email-bgolaszewski@baylibre.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
None of these files are actually using any __init type directives
and hence don't need to include <linux/init.h>. Most are just a
left over from __devinit and __cpuinit removal, or simply due to
code getting copied from one driver to the next.
[ hpa: undid incorrect removal from arch/x86/kernel/head_32.S ]
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Link: http://lkml.kernel.org/r/1389054026-12947-1-git-send-email-paul.gortmaker@windriver.com
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
The __cpuinit type of throwaway sections might have made sense
some time ago when RAM was more constrained, but now the savings
do not offset the cost and complications. For example, the fix in
commit 5e427ec2d0 ("x86: Fix bit corruption at CPU resume time")
is a good example of the nasty type of bugs that can be created
with improper use of the various __init prefixes.
After a discussion on LKML[1] it was decided that cpuinit should go
the way of devinit and be phased out. Once all the users are gone,
we can then finally remove the macros themselves from linux/init.h.
Note that some harmless section mismatch warnings may result, since
notify_cpu_starting() and cpu_up() are arch independent (kernel/cpu.c)
are flagged as __cpuinit -- so if we remove the __cpuinit from
arch specific callers, we will also get section mismatch warnings.
As an intermediate step, we intend to turn the linux/init.h cpuinit
content into no-ops as early as possible, since that will get rid
of these warnings. In any case, they are temporary and harmless.
This removes all the arch/x86 uses of the __cpuinit macros from
all C files. x86 only had the one __CPUINIT used in assembly files,
and it wasn't paired off with a .previous or a __FINIT, so we can
delete it directly w/o any corresponding additional change there.
[1] https://lkml.org/lkml/2013/5/20/589
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org
Acked-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: H. Peter Anvin <hpa@linux.intel.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
For each logical CPU that is coming online, we spend 20msec for
checking the TSC synchronization. And as this is done
sequentially for each logical CPU boot, this time gets added up
depending on the number of logical CPU's supported by the
platform.
Minimize this by using the socket topology information.
If the target CPU coming online doesn't have any of its
core-siblings online, a timeout of 20msec will be used for the
TSC-warp measurement loop. Otherwise a smaller timeout of 2msec
will be used, as we have some information about this socket
already (and this information grows as we have more and more
logical-siblings in that socket).
Ideally we should be able to skip the TSC sync check on the
other core-siblings, if the first logical CPU in a socket passed
the sync test. But as the TSC is per-logical CPU and can
potentially be modified wrongly by the bios before the OS boot,
TSC sync test for smaller duration should be able to catch such
errors. Also this will catch the condition where all the cores
in the socket doesn't get reset at the same time.
For example, with this modification, time spent in TSC sync
checks on a 4 socket 10-core with HT system gets reduced from
1580msec to 212msec.
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Acked-by: Arjan van de Ven <arjan@linux.intel.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Jack Steiner <steiner@sgi.com>
Cc: venki@google.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/1328581940.29790.20.camel@sbsiddha-desk.sc.intel.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
tsc=reliable boot parameter is supposed to skip all the TSC
stablility checks during boot time.
On a 8-socket system where we want to run an experiment with the
"tsc=reliable" boot option, TSC synchronization checks are not
getting skipped and marking the TSC as not stable.
Check for tsc_clocksource_reliable (which is set via
tsc=reliable or for platforms supporting synthetic TSC_RELIABLE
feature bit etc) and when set, skip the TSC synchronization
tests during boot.
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Acked-by: John Stultz <johnstul@us.ibm.com>
Tested-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/1320446537.15071.14.camel@sbsiddha-desk.sc.intel.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Name space cleanup. No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: linux-arch@vger.kernel.org
Further name space cleanup. No functional change
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: linux-arch@vger.kernel.org
The raw_spin* namespace was taken by lockdep for the architecture
specific implementations. raw_spin_* would be the ideal name space for
the spinlocks which are not converted to sleeping locks in preempt-rt.
Linus suggested to convert the raw_ to arch_ locks and cleanup the
name space instead of using an artifical name like core_spin,
atomic_spin or whatever
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: linux-arch@vger.kernel.org
Limit the number of per cpu TSC sync messages by only printing
to the console if an error occurs, otherwise print as a DEBUG
message.
The info message "Skipping synchronization ..." is only printed
after the last cpu has booted.
Signed-off-by: Mike Travis <travis@sgi.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Roland Dreier <rdreier@cisco.com>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Cc: Tejun Heo <tj@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Cc: Yinghai Lu <yhlu.kernel@gmail.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Cc: Jack Steiner <steiner@sgi.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20091118002222.181053000@alcatraz.americas.sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
On modern systems, the kernel prints the message
Skipping synchronization checks as TSC is reliable.
once for every non-boot CPU.
This gets kind of ridiculous on huge systems; for example, on a
64-thread system I was lucky enough to get:
$ dmesg | grep 'TSC is reliable' | wc
63 567 4221
There's no point to doing this for every CPU, since the code is
just checking the boot CPU anyway, so change this to a
printk_once() to make the message appears only once.
Signed-off-by: Roland Dreier <rolandd@cisco.com>
LKML-Reference: <adazl8l2swc.fsf@cisco.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
- remove unused define
- make the lock variable definition stand out some more
- convert KERN_* to pr_info() / pr_warning()
[ Impact: cleanup ]
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix incorrectly marked unstable TSC clock
Patch (commit 0d12cdd "sched: improve sched_clock() performance") has
a regression on one of the test systems here.
With the patch, I see:
checking TSC synchronization [CPU#0 -> CPU#1]:
Measured 28 cycles TSC warp between CPUs, turning off TSC clock.
Marking TSC unstable due to check_tsc_sync_source failed
Whereas, without the patch syncs pass fine on all CPUs:
checking TSC synchronization [CPU#0 -> CPU#1]: passed.
Due to this, TSC is marked unstable, when it is not actually unstable.
This is because syncs in check_tsc_wrap() goes away due to this commit.
As per the discussion on this thread, correct way to fix this is to add
explicit syncs as below?
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: Changes timebase calibration on Vmware.
Use the synthetic TSC_RELIABLE bit to workaround virtualization anomalies.
Virtual TSCs can be kept nearly in sync, but because the virtual TSC
offset is set by software, it's not perfect. So, the TSC
synchronization test can fail. Even then the TSC can be used as a
clocksource since the VMware platform exports a reliable TSC to the
guest for timekeeping purposes. Use this bit to check if we need to
skip the TSC sync checks.
Along with this also set the CONSTANT_TSC bit when on VMware, since we
still want to use TSC as clocksource on VM running over hardware which
has unsynchronized TSC's (opteron's), since the hypervisor will take
care of providing consistent TSC to the guest.
Signed-off-by: Alok N Kataria <akataria@vmware.com>
Signed-off-by: Dan Hecht <dhecht@vmware.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Use WARN() instead of a printk+WARN_ON() pair; this way the message
becomes part of the warning section for better reporting/collection.
This also allowed the folding of some if()'s into the WARN()
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Cc: akpm@linux-foundation.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
add warning to check_tsc_warp() - if get_cycles() does not progress.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
100 million max # of loops is a bit too much - reduce it to 10 million.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
rdtsc is now speculation-safe, so no need for the sync variants of
the APIs.
[ mingo@elte.hu: removed the nsec_barrier() complication. ]
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Since the x86 merge, lots of files that referenced their own filenames
are no longer correct. Rather than keep them up to date, just delete
them, as they add no real value.
Additionally:
- fix up comment formatting in scx200_32.c
- Remove a credit from myself in setup_64.c from a time when we had no SCM
- remove longwinded history from tsc_32.c which can be figured out from
git.
Signed-off-by: Dave Jones <davej@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Andy Lutomirski