linux/arch
Andy Lutomirski 6b078f5de7 x86, vdso, pvclock: Simplify and speed up the vdso pvclock reader
The pvclock vdso code was too abstracted to understand easily
and excessively paranoid.  Simplify it for a huge speedup.

This opens the door for additional simplifications, as the vdso
no longer accesses the pvti for any vcpu other than vcpu 0.

Before, vclock_gettime using kvm-clock took about 45ns on my
machine. With this change, it takes 29ns, which is almost as
fast as the pure TSC implementation.

Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
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: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/6b51dcc41f1b101f963945c5ec7093d72bdac429.1449702533.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-12-11 08:56:02 +01:00
..
alpha mm: mlock: add mlock flags to enable VM_LOCKONFAULT usage 2015-11-05 19:34:48 -08:00
arc ARC fixes for 4.4-rc1 2015-11-14 09:09:37 -08:00
arm USB fixes for 4.4-rc2 2015-11-22 13:15:05 -08:00
arm64 arm64 fixes: 2015-11-19 12:21:23 -08:00
avr32 dmaengine updates for 4.4-rc1 2015-11-10 10:05:17 -08:00
blackfin Merge branch 'strscpy' of git://git.kernel.org/pub/scm/linux/kernel/git/cmetcalf/linux-tile 2015-10-04 16:31:13 +01:00
c6x irqdomain: Use irq_domain_get_of_node() instead of direct field access 2015-10-13 19:01:23 +02:00
cris cris: Drop reference to get_cmos_time() 2015-11-02 20:03:05 +01:00
frv kmap_atomic_to_page() has no users, remove it 2015-11-09 15:11:24 -08:00
h8300 h8300 update for v4.4 2015-11-12 15:26:39 -08:00
hexagon Linux 4.3-rc4 2015-10-06 17:10:28 +02:00
ia64 Power management and ACPI updates for v4.4-rc1 2015-11-04 18:10:13 -08:00
m32r Linux 4.3-rc4 2015-10-06 17:10:28 +02:00
m68k block: change ->make_request_fn() and users to return a queue cookie 2015-11-07 10:40:46 -07:00
metag Metag architecture changes for v4.4 2015-11-10 16:24:25 -08:00
microblaze kmap_atomic_to_page() has no users, remove it 2015-11-09 15:11:24 -08:00
mips MIPS: ath79: Add a machine entry for booting OF machines 2015-11-20 15:44:57 +01:00
mn10300 Linux 4.3-rc4 2015-10-06 17:10:28 +02:00
nios2 nios2 update for v4.4-rc1 2015-11-09 16:36:10 -08:00
openrisc
parisc Merge branch 'parisc-4.4-2' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux 2015-11-22 12:50:58 -08:00
powerpc powerpc: Wire up sys_mlock2() 2015-11-16 17:05:53 +11:00
s390 s390: remove SALIPL loader 2015-11-16 12:51:11 +01:00
score Merge branch 'strscpy' of git://git.kernel.org/pub/scm/linux/kernel/git/cmetcalf/linux-tile 2015-10-04 16:31:13 +01:00
sh Merge branch 'akpm' (patches from Andrew) 2015-11-07 14:32:45 -08:00
sparc sparc/sparc64: allocate sys_membarrier system call number 2015-11-09 15:11:24 -08:00
tile kmap_atomic_to_page() has no users, remove it 2015-11-09 15:11:24 -08:00
um um: Switch clocksource to hrtimers 2015-11-06 22:54:49 +01:00
unicore32 pwm: Changes for v4.4-rc1 2015-11-11 09:16:10 -08:00
x86 x86, vdso, pvclock: Simplify and speed up the vdso pvclock reader 2015-12-11 08:56:02 +01:00
xtensa Merge branch 'for-4.4/io-poll' of git://git.kernel.dk/linux-block 2015-11-10 17:23:49 -08:00
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