linux/arch/powerpc
Paul Mackerras 66feed61cd KVM: PPC: Book3S HV: Use msgsnd for signalling threads on POWER8
This uses msgsnd where possible for signalling other threads within
the same core on POWER8 systems, rather than IPIs through the XICS
interrupt controller.  This includes waking secondary threads to run
the guest, the interrupts generated by the virtual XICS, and the
interrupts to bring the other threads out of the guest when exiting.

Aggregated statistics from debugfs across vcpus for a guest with 32
vcpus, 8 threads/vcore, running on a POWER8, show this before the
change:

 rm_entry:     3387.6ns (228 - 86600, 1008969 samples)
  rm_exit:     4561.5ns (12 - 3477452, 1009402 samples)
  rm_intr:     1660.0ns (12 - 553050, 3600051 samples)

and this after the change:

 rm_entry:     3060.1ns (212 - 65138, 953873 samples)
  rm_exit:     4244.1ns (12 - 9693408, 954331 samples)
  rm_intr:     1342.3ns (12 - 1104718, 3405326 samples)

for a test of booting Fedora 20 big-endian to the login prompt.

The time taken for a H_PROD hcall (which is handled in the host
kernel) went down from about 35 microseconds to about 16 microseconds
with this change.

The noinline added to kvmppc_run_core turned out to be necessary for
good performance, at least with gcc 4.9.2 as packaged with Fedora 21
and a little-endian POWER8 host.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
2015-04-21 15:21:34 +02:00
..
boot powerpc: dts: pq3/85xx: Fix GPIO address 2015-01-29 23:04:32 -06:00
configs The clock framework changes for 3.20 contain the usual driver additions, 2015-02-21 12:30:30 -08:00
crypto crypto: add missing crypto module aliases 2015-01-13 22:29:11 +11:00
include KVM: PPC: Book3S HV: Translate kvmhv_commence_exit to C 2015-04-21 15:21:34 +02:00
kernel KVM: PPC: Book3S HV: Use msgsnd for signalling threads on POWER8 2015-04-21 15:21:34 +02:00
kvm KVM: PPC: Book3S HV: Use msgsnd for signalling threads on POWER8 2015-04-21 15:21:34 +02:00
lib powerpc: Export __spin_yield 2015-04-21 15:21:28 +02:00
math-emu powerpc: Correct emulated mtfsf instruction 2014-04-07 10:33:11 +10:00
mm powerpc: drop _PAGE_FILE and pte_file()-related helpers 2015-02-16 17:56:05 -08:00
net module: remove mod arg from module_free, rename module_memfree(). 2015-01-20 11:38:33 +10:30
oprofile powerpc updates for 3.19 2014-12-11 17:48:14 -08:00
perf Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/scottwood/linux into next 2015-02-04 12:03:21 +11:00
platforms KVM: PPC: Book3S HV: Add fast real-mode H_RANDOM implementation. 2015-04-21 15:21:29 +02:00
sysdev powerpc: use %*pb[l] to print bitmaps including cpumasks and nodemasks 2015-02-13 21:21:36 -08:00
xmon powerpc updates for 3.20 2015-02-11 18:15:38 -08:00
Kconfig powerpc/mm: fix undefined reference to `.__kernel_map_pages' on FSL PPC64 2015-01-28 14:22:22 +11:00
Kconfig.debug Patch queue for ppc - 2014-08-01 2014-08-05 09:58:11 +02:00
Makefile kbuild: do not add $(call ...) to invoke cc-version or cc-fullversion 2015-01-09 17:25:44 +01:00
relocs_check.pl