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  1. 01 11月, 2016 1 次提交
    • A
      x86/fpu: Remove clts() · af25ed59
      由 Andy Lutomirski 提交于 
      The kernel doesn't use clts() any more.  Remove it and all of its
paravirt infrastructure.

A careful reader may notice that xen_clts() appears to have been
buggy -- it didn't update xen_cr0_value.
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kvm list <kvm@vger.kernel.org>
Link: http://lkml.kernel.org/r/3d3c8ca62f17579b9849a013d71e59a4d5d1b079.1477951965.git.luto@kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
      af25ed59
  3. 30 9月, 2016 2 次提交
  5. 22 4月, 2016 2 次提交
    • L
      x86/paravirt: Remove paravirt_enabled() · 867fe800
      由 Luis R. Rodriguez 提交于 
      Now that all previous paravirt_enabled() uses were replaced with proper
x86 semantics by the previous patches we can remove the unused
paravirt_enabled() mechanism.
Signed-off-by: NLuis R. Rodriguez <mcgrof@kernel.org>
Acked-by: NJuergen Gross <jgross@suse.com>
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: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: andrew.cooper3@citrix.com
Cc: andriy.shevchenko@linux.intel.com
Cc: bigeasy@linutronix.de
Cc: boris.ostrovsky@oracle.com
Cc: david.vrabel@citrix.com
Cc: ffainelli@freebox.fr
Cc: george.dunlap@citrix.com
Cc: glin@suse.com
Cc: jlee@suse.com
Cc: josh@joshtriplett.org
Cc: julien.grall@linaro.org
Cc: konrad.wilk@oracle.com
Cc: kozerkov@parallels.com
Cc: lenb@kernel.org
Cc: lguest@lists.ozlabs.org
Cc: linux-acpi@vger.kernel.org
Cc: lv.zheng@intel.com
Cc: matt@codeblueprint.co.uk
Cc: mbizon@freebox.fr
Cc: rjw@rjwysocki.net
Cc: robert.moore@intel.com
Cc: rusty@rustcorp.com.au
Cc: tiwai@suse.de
Cc: toshi.kani@hp.com
Cc: xen-devel@lists.xensource.com
Link: http://lkml.kernel.org/r/1460592286-300-15-git-send-email-mcgrof@kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
      867fe800
    • L
      x86/rtc: Replace paravirt rtc check with platform legacy quirk · 8d152e7a
      由 Luis R. Rodriguez 提交于 
      We have 4 types of x86 platforms that disable RTC:

  * Intel MID
  * Lguest - uses paravirt
  * Xen dom-U - uses paravirt
  * x86 on legacy systems annotated with an ACPI legacy flag

We can consolidate all of these into a platform specific legacy
quirk set early in boot through i386_start_kernel() and through
x86_64_start_reservations(). This deals with the RTC quirks which
we can rely on through the hardware subarch, the ACPI check can
be dealt with separately.

For Xen things are bit more complex given that the @X86_SUBARCH_XEN
x86_hardware_subarch is shared on for Xen which uses the PV path for
both domU and dom0. Since the semantics for differentiating between
the two are Xen specific we provide a platform helper to help override
default legacy features -- x86_platform.set_legacy_features(). Use
of this helper is highly discouraged, its only purpose should be
to account for the lack of semantics available within your given
x86_hardware_subarch.

As per 0-day, this bumps the vmlinux size using i386-tinyconfig as
follows:

TOTAL   TEXT   init.text    x86_early_init_platform_quirks()
+70     +62    +62          +43

Only 8 bytes overhead total, as the main increase in size is
all removed via __init.
Suggested-by: NIngo Molnar <mingo@kernel.org>
Signed-off-by: NLuis R. Rodriguez <mcgrof@kernel.org>
Reviewed-by: NJuergen Gross <jgross@suse.com>
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: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: andrew.cooper3@citrix.com
Cc: andriy.shevchenko@linux.intel.com
Cc: bigeasy@linutronix.de
Cc: boris.ostrovsky@oracle.com
Cc: david.vrabel@citrix.com
Cc: ffainelli@freebox.fr
Cc: george.dunlap@citrix.com
Cc: glin@suse.com
Cc: jlee@suse.com
Cc: josh@joshtriplett.org
Cc: julien.grall@linaro.org
Cc: konrad.wilk@oracle.com
Cc: kozerkov@parallels.com
Cc: lenb@kernel.org
Cc: lguest@lists.ozlabs.org
Cc: linux-acpi@vger.kernel.org
Cc: lv.zheng@intel.com
Cc: matt@codeblueprint.co.uk
Cc: mbizon@freebox.fr
Cc: rjw@rjwysocki.net
Cc: robert.moore@intel.com
Cc: rusty@rustcorp.com.au
Cc: tiwai@suse.de
Cc: toshi.kani@hp.com
Cc: xen-devel@lists.xensource.com
Link: http://lkml.kernel.org/r/1460592286-300-5-git-send-email-mcgrof@kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
      8d152e7a
  7. 13 4月, 2016 3 次提交
  9. 24 2月, 2016 1 次提交
    • J
      x86/paravirt: Create a stack frame in PV_CALLEE_SAVE_REGS_THUNK · 87b240cb
      由 Josh Poimboeuf 提交于 
      A function created with the PV_CALLEE_SAVE_REGS_THUNK macro doesn't set
up a new stack frame before the call instruction, which breaks frame
pointer convention if CONFIG_FRAME_POINTER is enabled and can result in
a bad stack trace.  Also, the thunk functions aren't annotated as ELF
callable functions.

Create a stack frame when CONFIG_FRAME_POINTER is enabled and add the
ELF function type.
Signed-off-by: NJosh Poimboeuf <jpoimboe@redhat.com>
Reviewed-by: NBorislav Petkov <bp@suse.de>
Cc: Alok Kataria <akataria@vmware.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Bernd Petrovitsch <bernd@petrovitsch.priv.at>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Chris J Arges <chris.j.arges@canonical.com>
Cc: Chris Wright <chrisw@sous-sol.org>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michal Marek <mmarek@suse.cz>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Pedro Alves <palves@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/a2cad74e87c4aba7fd0f54a1af312e66a824a575.1453405861.git.jpoimboe@redhat.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      87b240cb
  11. 20 12月, 2015 1 次提交
    • D
      x86/paravirt: Prevent rtc_cmos platform device init on PV guests · d8c98a1d
      由 David Vrabel 提交于 
      Adding the rtc platform device in non-privileged Xen PV guests causes
an IRQ conflict because these guests do not have legacy PIC and may
allocate irqs in the legacy range.

In a single VCPU Xen PV guest we should have:

/proc/interrupts:
           CPU0
  0:       4934  xen-percpu-virq      timer0
  1:          0  xen-percpu-ipi       spinlock0
  2:          0  xen-percpu-ipi       resched0
  3:          0  xen-percpu-ipi       callfunc0
  4:          0  xen-percpu-virq      debug0
  5:          0  xen-percpu-ipi       callfuncsingle0
  6:          0  xen-percpu-ipi       irqwork0
  7:        321   xen-dyn-event     xenbus
  8:         90   xen-dyn-event     hvc_console
  ...

But hvc_console cannot get its interrupt because it is already in use
by rtc0 and the console does not work.

  genirq: Flags mismatch irq 8. 00000000 (hvc_console) vs. 00000000 (rtc0)

We can avoid this problem by realizing that unprivileged PV guests (both
Xen and lguests) are not supposed to have rtc_cmos device and so
adding it is not necessary.

Privileged guests (i.e. Xen's dom0) do use it but they should not have
irq conflicts since they allocate irqs above legacy range (above
gsi_top, in fact).

Instead of explicitly testing whether the guest is privileged we can
extend pv_info structure to include information about guest's RTC
support.
Reported-and-tested-by: NSander Eikelenboom <linux@eikelenboom.it>
Signed-off-by: NDavid Vrabel <david.vrabel@citrix.com>
Signed-off-by: NBoris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: vkuznets@redhat.com
Cc: xen-devel@lists.xenproject.org
Cc: konrad.wilk@oracle.com
Cc: stable@vger.kernel.org # 4.2+
Link: http://lkml.kernel.org/r/1449842873-2613-1-git-send-email-boris.ostrovsky@oracle.comSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
      d8c98a1d
  13. 26 11月, 2015 1 次提交
  15. 23 11月, 2015 2 次提交
  17. 19 11月, 2015 1 次提交
  19. 23 8月, 2015 1 次提交
  21. 06 7月, 2015 1 次提交
    • A
      x86/asm/tsc, x86/paravirt: Remove read_tsc() and read_tscp() paravirt hooks · 9261e050
      由 Andy Lutomirski 提交于 
      We've had ->read_tsc() and ->read_tscp() paravirt hooks since
the very beginning of paravirt, i.e.,

  d3561b7f ("[PATCH] paravirt: header and stubs for paravirtualisation").

AFAICT, the only paravirt guest implementation that ever
replaced these calls was vmware, and it's gone. Arguably even
vmware shouldn't have hooked RDTSC -- we fully support systems
that don't have a TSC at all, so there's no point for a paravirt
implementation to pretend that we have a TSC but to replace it.

I also doubt that these hooks actually worked. Calls to rdtscl()
and rdtscll(), which respected the hooks, were used seemingly
interchangeably with native_read_tsc(), which did not.

Just remove them. If anyone ever needs them again, they can try
to make a case for why they need them.

Before, on a paravirt config:
  text    	data     bss     dec     hex filename
  12618257      1816384 1093632 15528273 ecf151 vmlinux

After:
  text		data     bss     dec     hex filename
  12617207      1816384 1093632 15527223 eced37 vmlinux
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Signed-off-by: NBorislav 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>
Cc: virtualization@lists.linux-foundation.org
Link: http://lkml.kernel.org/r/d08a2600fb298af163681e5efd8e599d889a5b97.1434501121.git.luto@kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
      9261e050
  23. 11 5月, 2015 1 次提交
    • I
      locking/pvqspinlock: Rename QUEUED_SPINLOCK to QUEUED_SPINLOCKS · 62c7a1e9
      由 Ingo Molnar 提交于 
      Valentin Rothberg reported that we use CONFIG_QUEUED_SPINLOCKS
in arch/x86/kernel/paravirt_patch_32.c, while the symbol is
called CONFIG_QUEUED_SPINLOCK. (Note the extra 'S')

But the typo was natural: the proper English term for such
a generic object would be 'queued spinlocks' - so rename
this and related symbols accordingly to the plural form.
Reported-by: NValentin Rothberg <valentinrothberg@gmail.com>
Cc: Douglas Hatch <doug.hatch@hp.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Scott J Norton <scott.norton@hp.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <Waiman.Long@hp.com>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>
      62c7a1e9
  25. 08 5月, 2015 1 次提交
    • P
      locking/pvqspinlock, x86: Implement the paravirt qspinlock call patching · f233f7f1
      由 Peter Zijlstra (Intel) 提交于 
      We use the regular paravirt call patching to switch between:

  native_queued_spin_lock_slowpath()	__pv_queued_spin_lock_slowpath()
  native_queued_spin_unlock()		__pv_queued_spin_unlock()

We use a callee saved call for the unlock function which reduces the
i-cache footprint and allows 'inlining' of SPIN_UNLOCK functions
again.

We further optimize the unlock path by patching the direct call with a
"movb $0,%arg1" if we are indeed using the native unlock code. This
makes the unlock code almost as fast as the !PARAVIRT case.

This significantly lowers the overhead of having
CONFIG_PARAVIRT_SPINLOCKS enabled, even for native code.
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: NWaiman Long <Waiman.Long@hp.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Daniel J Blueman <daniel@numascale.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Douglas Hatch <doug.hatch@hp.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paolo Bonzini <paolo.bonzini@gmail.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Scott J Norton <scott.norton@hp.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: virtualization@lists.linux-foundation.org
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/1429901803-29771-10-git-send-email-Waiman.Long@hp.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      f233f7f1
  27. 15 4月, 2015 1 次提交
  29. 03 4月, 2015 1 次提交
  31. 04 2月, 2015 1 次提交
  33. 19 11月, 2014 1 次提交
    • D
      x86: Cleanly separate use of asm-generic/mm_hooks.h · a1ea1c03
      由 Dave Hansen 提交于 
      asm-generic/mm_hooks.h provides some generic fillers for the 90%
of architectures that do not need to hook some mmap-manipulation
functions.  A comment inside says:

> Define generic no-op hooks for arch_dup_mmap and
> arch_exit_mmap, to be included in asm-FOO/mmu_context.h
> for any arch FOO which doesn't need to hook these.

So, does x86 need to hook these?  It depends on CONFIG_PARAVIRT.
We *conditionally* include this generic header if we have
CONFIG_PARAVIRT=n.  That's madness.

With this patch, x86 stops using asm-generic/mmu_hooks.h entirely.
We use our own copies of the functions.  The paravirt code
provides some stubs if it is disabled, and we always call those
stubs in our x86-private versions of arch_exit_mmap() and
arch_dup_mmap().
Signed-off-by: NDave Hansen <dave.hansen@linux.intel.com>
Cc: Dave Hansen <dave@sr71.net>
Cc: x86@kernel.org
Link: http://lkml.kernel.org/r/20141118182349.14567FA5@viggo.jf.intel.comSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
      a1ea1c03
  35. 30 1月, 2014 1 次提交
  37. 09 8月, 2013 3 次提交
    • J
      x86, ticketlock: Add slowpath logic · 96f853ea
      由 Jeremy Fitzhardinge 提交于 
      Maintain a flag in the LSB of the ticket lock tail which indicates
whether anyone is in the lock slowpath and may need kicking when
the current holder unlocks.  The flags are set when the first locker
enters the slowpath, and cleared when unlocking to an empty queue (ie,
no contention).

In the specific implementation of lock_spinning(), make sure to set
the slowpath flags on the lock just before blocking.  We must do
this before the last-chance pickup test to prevent a deadlock
with the unlocker:

Unlocker			Locker
				test for lock pickup
					-> fail
unlock
test slowpath
	-> false
				set slowpath flags
				block

Whereas this works in any ordering:

Unlocker			Locker
				set slowpath flags
				test for lock pickup
					-> fail
				block
unlock
test slowpath
	-> true, kick

If the unlocker finds that the lock has the slowpath flag set but it is
actually uncontended (ie, head == tail, so nobody is waiting), then it
clears the slowpath flag.

The unlock code uses a locked add to update the head counter.  This also
acts as a full memory barrier so that its safe to subsequently
read back the slowflag state, knowing that the updated lock is visible
to the other CPUs.  If it were an unlocked add, then the flag read may
just be forwarded from the store buffer before it was visible to the other
CPUs, which could result in a deadlock.

Unfortunately this means we need to do a locked instruction when
unlocking with PV ticketlocks.  However, if PV ticketlocks are not
enabled, then the old non-locked "add" is the only unlocking code.

Note: this code relies on gcc making sure that unlikely() code is out of
line of the fastpath, which only happens when OPTIMIZE_SIZE=n.  If it
doesn't the generated code isn't too bad, but its definitely suboptimal.

Thanks to Srivatsa Vaddagiri for providing a bugfix to the original
version of this change, which has been folded in.
Thanks to Stephan Diestelhorst for commenting on some code which relied
on an inaccurate reading of the x86 memory ordering rules.
Signed-off-by: NJeremy Fitzhardinge <jeremy@goop.org>
Link: http://lkml.kernel.org/r/1376058122-8248-11-git-send-email-raghavendra.kt@linux.vnet.ibm.comSigned-off-by: NSrivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Reviewed-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Stephan Diestelhorst <stephan.diestelhorst@amd.com>
Signed-off-by: NRaghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Acked-by: NIngo Molnar <mingo@kernel.org>
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>
      96f853ea
    • J
      x86, pvticketlock: Use callee-save for lock_spinning · 354714dd
      由 Jeremy Fitzhardinge 提交于 
      Although the lock_spinning calls in the spinlock code are on the
uncommon path, their presence can cause the compiler to generate many
more register save/restores in the function pre/postamble, which is in
the fast path.  To avoid this, convert it to using the pvops callee-save
calling convention, which defers all the save/restores until the actual
function is called, keeping the fastpath clean.
Signed-off-by: NJeremy Fitzhardinge <jeremy@goop.org>
Link: http://lkml.kernel.org/r/1376058122-8248-8-git-send-email-raghavendra.kt@linux.vnet.ibm.comReviewed-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Tested-by: NAttilio Rao <attilio.rao@citrix.com>
Signed-off-by: NRaghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Acked-by: NIngo Molnar <mingo@kernel.org>
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>
      354714dd
    • J
      x86, spinlock: Replace pv spinlocks with pv ticketlocks · 545ac138
      由 Jeremy Fitzhardinge 提交于 
      Rather than outright replacing the entire spinlock implementation in
order to paravirtualize it, keep the ticket lock implementation but add
a couple of pvops hooks on the slow patch (long spin on lock, unlocking
a contended lock).

Ticket locks have a number of nice properties, but they also have some
surprising behaviours in virtual environments.  They enforce a strict
FIFO ordering on cpus trying to take a lock; however, if the hypervisor
scheduler does not schedule the cpus in the correct order, the system can
waste a huge amount of time spinning until the next cpu can take the lock.

(See Thomas Friebel's talk "Prevent Guests from Spinning Around"
http://www.xen.org/files/xensummitboston08/LHP.pdf for more details.)

To address this, we add two hooks:
 - __ticket_spin_lock which is called after the cpu has been
   spinning on the lock for a significant number of iterations but has
   failed to take the lock (presumably because the cpu holding the lock
   has been descheduled).  The lock_spinning pvop is expected to block
   the cpu until it has been kicked by the current lock holder.
 - __ticket_spin_unlock, which on releasing a contended lock
   (there are more cpus with tail tickets), it looks to see if the next
   cpu is blocked and wakes it if so.

When compiled with CONFIG_PARAVIRT_SPINLOCKS disabled, a set of stub
functions causes all the extra code to go away.

Results:
=======
setup: 32 core machine with 32 vcpu KVM guest (HT off)  with 8GB RAM
base = 3.11-rc
patched = base + pvspinlock V12

+-----------------+----------------+--------+
 dbench (Throughput in MB/sec. Higher is better)
+-----------------+----------------+--------+
|   base (stdev %)|patched(stdev%) | %gain  |
+-----------------+----------------+--------+
| 15035.3   (0.3) |15150.0   (0.6) |   0.8  |
|  1470.0   (2.2) | 1713.7   (1.9) |  16.6  |
|   848.6   (4.3) |  967.8   (4.3) |  14.0  |
|   652.9   (3.5) |  685.3   (3.7) |   5.0  |
+-----------------+----------------+--------+

pvspinlock shows benefits for overcommit ratio > 1 for PLE enabled cases,
and undercommits results are flat
Signed-off-by: NJeremy Fitzhardinge <jeremy@goop.org>
Link: http://lkml.kernel.org/r/1376058122-8248-2-git-send-email-raghavendra.kt@linux.vnet.ibm.comReviewed-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Tested-by: NAttilio Rao <attilio.rao@citrix.com>
[ Raghavendra: Changed SPIN_THRESHOLD, fixed redefinition of arch_spinlock_t]
Signed-off-by: NRaghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Acked-by: NIngo Molnar <mingo@kernel.org>
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>
      545ac138
  39. 12 4月, 2013 1 次提交
  41. 11 4月, 2013 1 次提交
  43. 19 12月, 2012 1 次提交
    • D
      x86, paravirt: fix build error when thp is disabled · c36e0501
      由 David Rientjes 提交于 
      With CONFIG_PARAVIRT=y and CONFIG_TRANSPARENT_HUGEPAGE=n, the build breaks
because set_pmd_at() is undeclared:

  mm/memory.c: In function 'do_pmd_numa_page':
  mm/memory.c:3520: error: implicit declaration of function 'set_pmd_at'
  mm/mprotect.c: In function 'change_pmd_protnuma':
  mm/mprotect.c:120: error: implicit declaration of function 'set_pmd_at'

This is because paravirt defines set_pmd_at() only when
CONFIG_TRANSPARENT_HUGEPAGE=y and such a restriction is unneeded.  The
fix is to define it for all CONFIG_PARAVIRT configurations.
Signed-off-by: NDavid Rientjes <rientjes@google.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      c36e0501
  45. 28 6月, 2012 1 次提交
    • A
      x86/flush_tlb: try flush_tlb_single one by one in flush_tlb_range · e7b52ffd
      由 Alex Shi 提交于 
      x86 has no flush_tlb_range support in instruction level. Currently the
flush_tlb_range just implemented by flushing all page table. That is not
the best solution for all scenarios. In fact, if we just use 'invlpg' to
flush few lines from TLB, we can get the performance gain from later
remain TLB lines accessing.

But the 'invlpg' instruction costs much of time. Its execution time can
compete with cr3 rewriting, and even a bit more on SNB CPU.

So, on a 512 4KB TLB entries CPU, the balance points is at:
	(512 - X) * 100ns(assumed TLB refill cost) =
		X(TLB flush entries) * 100ns(assumed invlpg cost)

Here, X is 256, that is 1/2 of 512 entries.

But with the mysterious CPU pre-fetcher and page miss handler Unit, the
assumed TLB refill cost is far lower then 100ns in sequential access. And
2 HT siblings in one core makes the memory access more faster if they are
accessing the same memory. So, in the patch, I just do the change when
the target entries is less than 1/16 of whole active tlb entries.
Actually, I have no data support for the percentage '1/16', so any
suggestions are welcomed.

As to hugetlb, guess due to smaller page table, and smaller active TLB
entries, I didn't see benefit via my benchmark, so no optimizing now.

My micro benchmark show in ideal scenarios, the performance improves 70
percent in reading. And in worst scenario, the reading/writing
performance is similar with unpatched 3.4-rc4 kernel.

Here is the reading data on my 2P * 4cores *HT NHM EP machine, with THP
'always':

multi thread testing, '-t' paramter is thread number:
	       	        with patch   unpatched 3.4-rc4
./mprotect -t 1           14ns		24ns
./mprotect -t 2           13ns		22ns
./mprotect -t 4           12ns		19ns
./mprotect -t 8           14ns		16ns
./mprotect -t 16          28ns		26ns
./mprotect -t 32          54ns		51ns
./mprotect -t 128         200ns		199ns

Single process with sequencial flushing and memory accessing:

		       	with patch   unpatched 3.4-rc4
./mprotect		    7ns			11ns
./mprotect -p 4096  -l 8 -n 10240
			    21ns		21ns

[ hpa: http://lkml.kernel.org/r/1B4B44D9196EFF41AE41FDA404FC0A100BFF94@SHSMSX101.ccr.corp.intel.com
  has additional performance numbers. ]
Signed-off-by: NAlex Shi <alex.shi@intel.com>
Link: http://lkml.kernel.org/r/1340845344-27557-3-git-send-email-alex.shi@intel.comSigned-off-by: NH. Peter Anvin <hpa@zytor.com>
      e7b52ffd
  47. 08 6月, 2012 1 次提交
  49. 06 6月, 2012 1 次提交
  51. 20 4月, 2012 1 次提交
  53. 05 3月, 2012 1 次提交
    • P
      BUG: headers with BUG/BUG_ON etc. need linux/bug.h · 187f1882
      由 Paul Gortmaker 提交于 
      If a header file is making use of BUG, BUG_ON, BUILD_BUG_ON, or any
other BUG variant in a static inline (i.e. not in a #define) then
that header really should be including <linux/bug.h> and not just
expecting it to be implicitly present.

We can make this change risk-free, since if the files using these
headers didn't have exposure to linux/bug.h already, they would have
been causing compile failures/warnings.
Signed-off-by: NPaul Gortmaker <paul.gortmaker@windriver.com>
      187f1882
  55. 24 2月, 2012 1 次提交
    • I
      static keys: Introduce 'struct static_key', static_key_true()/false() and... · c5905afb
      由 Ingo Molnar 提交于 
      static keys: Introduce 'struct static_key', static_key_true()/false() and static_key_slow_[inc|dec]()

So here's a boot tested patch on top of Jason's series that does
all the cleanups I talked about and turns jump labels into a
more intuitive to use facility. It should also address the
various misconceptions and confusions that surround jump labels.

Typical usage scenarios:

        #include <linux/static_key.h>

        struct static_key key = STATIC_KEY_INIT_TRUE;

        if (static_key_false(&key))
                do unlikely code
        else
                do likely code

Or:

        if (static_key_true(&key))
                do likely code
        else
                do unlikely code

The static key is modified via:

        static_key_slow_inc(&key);
        ...
        static_key_slow_dec(&key);

The 'slow' prefix makes it abundantly clear that this is an
expensive operation.

I've updated all in-kernel code to use this everywhere. Note
that I (intentionally) have not pushed through the rename
blindly through to the lowest levels: the actual jump-label
patching arch facility should be named like that, so we want to
decouple jump labels from the static-key facility a bit.

On non-jump-label enabled architectures static keys default to
likely()/unlikely() branches.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Acked-by: NJason Baron <jbaron@redhat.com>
Acked-by: NSteven Rostedt <rostedt@goodmis.org>
Cc: a.p.zijlstra@chello.nl
Cc: mathieu.desnoyers@efficios.com
Cc: davem@davemloft.net
Cc: ddaney.cavm@gmail.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20120222085809.GA26397@elte.huSigned-off-by: NIngo Molnar <mingo@elte.hu>
      c5905afb
  57. 14 7月, 2011 1 次提交
  59. 26 1月, 2011 1 次提交
  61. 14 1月, 2011 1 次提交
  63. 28 12月, 2010 1 次提交
    • C
      x86, paravirt: Use native_halt on a halt, not native_safe_halt · c8217b83
      由 Cliff Wickman 提交于 
      halt() should use native_halt()
safe_halt() uses native_safe_halt()

If CONFIG_PARAVIRT=y, halt() is defined in arch/x86/include/asm/paravirt.h as

static inline void halt(void)
{
        PVOP_VCALL0(pv_irq_ops.safe_halt);
}

Otherwise (no CONFIG_PARAVIRT) halt() in arch/x86/include/asm/irqflags.h is

static inline void halt(void)
{
        native_halt();
}

So it looks to me like the CONFIG_PARAVIRT case of using native_safe_halt()
for a halt() is an oversight.
Am I missing something?

It probably hasn't shown up as a problem because the local apic is disabled
on a shutdown or restart.  But if we disable interrupts and call halt()
we shouldn't expect that the halt() will re-enable interrupts.
Signed-off-by: NCliff Wickman <cpw@sgi.com>
LKML-Reference: <E1PSBcz-0001g1-FM@eag09.americas.sgi.com>
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>
      c8217b83
  65. 11 11月, 2010 1 次提交
    • S
      tracing: Force arch_local_irq_* notrace for paravirt · b5908548
      由 Steven Rostedt 提交于 
      When running ktest.pl randconfig tests, I would sometimes trigger
a lockdep annotation bug (possible reason: unannotated irqs-on).

This triggering happened right after function tracer self test was
executed. After doing a config bisect I found that this was caused with
having function tracer, paravirt guest, prove locking, and rcu torture
all enabled.

The rcu torture just enhanced the likelyhood of triggering the bug.
Prove locking was needed, since it was the thing that was bugging.
Function tracer would trace and disable interrupts in all sorts
of funny places.
paravirt guest would turn arch_local_irq_* into functions that would
be traced.

Besides the fact that tracing arch_local_irq_* is just a bad idea,
this is what is happening.

The bug happened simply in the local_irq_restore() code:

		if (raw_irqs_disabled_flags(flags)) {	\
			raw_local_irq_restore(flags);	\
			trace_hardirqs_off();		\
		} else {				\
			trace_hardirqs_on();		\
			raw_local_irq_restore(flags);	\
		}					\

The raw_local_irq_restore() was defined as arch_local_irq_restore().

Now imagine, we are about to enable interrupts. We go into the else
case and call trace_hardirqs_on() which tells lockdep that we are enabling
interrupts, so it sets the current->hardirqs_enabled = 1.

Then we call raw_local_irq_restore() which calls arch_local_irq_restore()
which gets traced!

Now in the function tracer we disable interrupts with local_irq_save().
This is fine, but flags is stored that we have interrupts disabled.

When the function tracer calls local_irq_restore() it does it, but this
time with flags set as disabled, so we go into the if () path.
This keeps interrupts disabled and calls trace_hardirqs_off() which
sets current->hardirqs_enabled = 0.

When the tracer is finished and proceeds with the original code,
we enable interrupts but leave current->hardirqs_enabled as 0. Which
now breaks lockdeps internal processing.

Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      b5908548