linux-stable/arch/x86/entry
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
..
syscalls mm: mlock: add new mlock system call 2015-11-05 19:34:48 -08:00
vdso x86, vdso, pvclock: Simplify and speed up the vdso pvclock reader 2015-12-11 08:56:02 +01:00
vsyscall x86/entry/vsyscall: Fix undefined symbol warning 2015-09-21 09:56:59 +02:00
calling.h x86/entry/64: Bypass enter_from_user_mode on non-context-tracking boots 2015-11-24 09:56:44 +01:00
common.c x86/entry/32: Fix entry_INT80_32() to expect interrupts to be on 2015-10-18 12:11:16 +02:00
entry_32.S x86/paravirt: Remove the unused irq_enable_sysexit pv op 2015-11-23 10:48:16 +01:00
entry_64.S x86/entry/64: Bypass enter_from_user_mode on non-context-tracking boots 2015-11-24 09:56:44 +01:00
entry_64_compat.S x86/entry, x86/paravirt: Remove the unused usergs_sysret32 PV op 2015-11-23 10:48:16 +01:00
Makefile x86/entry: Move C entry and exit code to arch/x86/entry/common.c 2015-07-07 10:59:05 +02:00
syscall_32.c x86/syscalls: Give sys_call_ptr_t a useful type 2015-10-09 09:41:08 +02:00
syscall_64.c x86/syscalls: Give sys_call_ptr_t a useful type 2015-10-09 09:41:08 +02:00
thunk_32.S Merge branch 'x86-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-06-22 17:59:09 -07:00
thunk_64.S Merge branch 'x86-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-06-22 17:59:09 -07:00