similar to: [PATCH 1/1] sched: provide common cpu_relax_yield definition

For spinning loops people do often use barrier() or cpu_relax(). For most architectures cpu_relax and barrier are the same, but on some architectures cpu_relax can add some latency. For example on power,sparc64 and arc, cpu_relax can shift the CPU towards other hardware threads in an SMT environment. On s390 cpu_relax does even more, it uses an hypercall to the hypervisor to give up the timeslice.

Peter, here is v2 with some improved patch descriptions and some fixes. The previous version has survived one day of linux-next and I only changed small parts. So unless there is some other issue, feel free to pull (or to apply the patches) to tip/locking. The following changes since commit 07d9a380680d1c0eb51ef87ff2eab5c994949e69: Linux 4.9-rc2 (2016-10-23 17:10:14 -0700) are available in

Peter, here is v2 with some improved patch descriptions and some fixes. The previous version has survived one day of linux-next and I only changed small parts. So unless there is some other issue, feel free to pull (or to apply the patches) to tip/locking. The following changes since commit 07d9a380680d1c0eb51ef87ff2eab5c994949e69: Linux 4.9-rc2 (2016-10-23 17:10:14 -0700) are available in

As there are no users left, we can remove cpu_relax_lowlatency. Signed-off-by: Christian Borntraeger <borntraeger at de.ibm.com> --- arch/alpha/include/asm/processor.h | 1 - arch/arc/include/asm/processor.h | 2 -- arch/arm/include/asm/processor.h | 1 - arch/arm64/include/asm/processor.h | 1 - arch/avr32/include/asm/processor.h | 1 -

What's left in processor_32.h and processor_64.h cannot be cleanly integrated. However, it's just a couple of definitions. They are moved to processor.h around ifdefs, and the original files are deleted. Note that there's much less headers included in the final version. Signed-off-by: Glauber de Oliveira Costa <gcosta@redhat.com> --- include/asm-x86/processor.h | 140

What's left in processor_32.h and processor_64.h cannot be cleanly integrated. However, it's just a couple of definitions. They are moved to processor.h around ifdefs, and the original files are deleted. Note that there's much less headers included in the final version. Signed-off-by: Glauber de Oliveira Costa <gcosta@redhat.com> --- include/asm-x86/processor.h | 140

This patch removes the __init modifier from an extern function declaration in acpi.h. Besides not being strictly needed, it requires the inclusion of linux/init.h, which is usually not even included directly, increasing header mess by a lot. Signed-off-by: Glauber de Oliveira Costa <gcosta@redhat.com> --- include/asm-x86/acpi.h | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-)

This patch removes the __init modifier from an extern function declaration in acpi.h. Besides not being strictly needed, it requires the inclusion of linux/init.h, which is usually not even included directly, increasing header mess by a lot. Signed-off-by: Glauber de Oliveira Costa <gcosta@redhat.com> --- include/asm-x86/acpi.h | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-)

On Tue, Oct 25, 2016 at 11:03:11AM +0200, Christian Borntraeger wrote: > For spinning loops people do often use barrier() or cpu_relax(). > For most architectures cpu_relax and barrier are the same, but on > some architectures cpu_relax can add some latency. > For example on power,sparc64 and arc, cpu_relax can shift the CPU > towards other hardware threads in an SMT environment.

On Tue, Oct 25, 2016 at 11:03:11AM +0200, Christian Borntraeger wrote: > For spinning loops people do often use barrier() or cpu_relax(). > For most architectures cpu_relax and barrier are the same, but on > some architectures cpu_relax can add some latency. > For example on power,sparc64 and arc, cpu_relax can shift the CPU > towards other hardware threads in an SMT environment.

On Tue, Nov 15, 2016 at 02:19:53PM +0100, Christian Borntraeger wrote: > On 11/15/2016 01:30 PM, Russell King - ARM Linux wrote: > > On Tue, Oct 25, 2016 at 11:03:11AM +0200, Christian Borntraeger wrote: > >> For spinning loops people do often use barrier() or cpu_relax(). > >> For most architectures cpu_relax and barrier are the same, but on > >> some

On Tue, Nov 15, 2016 at 02:19:53PM +0100, Christian Borntraeger wrote: > On 11/15/2016 01:30 PM, Russell King - ARM Linux wrote: > > On Tue, Oct 25, 2016 at 11:03:11AM +0200, Christian Borntraeger wrote: > >> For spinning loops people do often use barrier() or cpu_relax(). > >> For most architectures cpu_relax and barrier are the same, but on > >> some

On Fri, Oct 21, 2016 at 01:58:55PM +0200, Christian Borntraeger wrote: > stop_machine can take a very long time if the hypervisor does > overcommitment for guest CPUs. When waiting for "the one", lets > give up our CPU by using the new cpu_relax_yield. This seems something that would apply to most other virt stuff. Lets Cc a few more lists for that. > Signed-off-by:

On Fri, Oct 21, 2016 at 01:58:55PM +0200, Christian Borntraeger wrote: > stop_machine can take a very long time if the hypervisor does > overcommitment for guest CPUs. When waiting for "the one", lets > give up our CPU by using the new cpu_relax_yield. This seems something that would apply to most other virt stuff. Lets Cc a few more lists for that. > Signed-off-by:

On 10/21/2016 04:57 PM, David Miller wrote: > From: Christian Borntraeger <borntraeger at de.ibm.com> > Date: Fri, 21 Oct 2016 13:58:53 +0200 > >> For spinning loops people did often use barrier() or cpu_relax(). >> For most architectures cpu_relax and barrier are the same, but on >> some architectures cpu_relax can add some latency. For example on s390 >>

On 10/21/2016 04:57 PM, David Miller wrote: > From: Christian Borntraeger <borntraeger at de.ibm.com> > Date: Fri, 21 Oct 2016 13:58:53 +0200 > >> For spinning loops people did often use barrier() or cpu_relax(). >> For most architectures cpu_relax and barrier are the same, but on >> some architectures cpu_relax can add some latency. For example on s390 >>

From: Martin Schwidefsky <schwidefsky at de.ibm.com> The SIE instruction on s390 uses the 2nd half of the page table page to virtualize the storage keys of a guest. This patch offers the s390_enable_sie function, which reorganizes the page tables of a single-threaded process to reserve space in the page table: s390_enable_sie makes sure that the process is single threaded and then uses

The 32-bit and 64-bit versions of copy_thread have functionally identical handling for copying the I/O bitmap, modulo differences in error handling. Clean up the error paths in both by moving the copy of the I/O bitmap to the end, to eliminate the need to free it if subsequent copy steps fail; move the resulting identical code to a static inline in a common header. Signed-off-by: Josh Triplett

On 11/15/2016 01:30 PM, Russell King - ARM Linux wrote: > On Tue, Oct 25, 2016 at 11:03:11AM +0200, Christian Borntraeger wrote: >> For spinning loops people do often use barrier() or cpu_relax(). >> For most architectures cpu_relax and barrier are the same, but on >> some architectures cpu_relax can add some latency. >> For example on power,sparc64 and arc, cpu_relax

On 11/15/2016 02:37 PM, Russell King - ARM Linux wrote: > On Tue, Nov 15, 2016 at 02:19:53PM +0100, Christian Borntraeger wrote: >> On 11/15/2016 01:30 PM, Russell King - ARM Linux wrote: >>> On Tue, Oct 25, 2016 at 11:03:11AM +0200, Christian Borntraeger wrote: >>>> For spinning loops people do often use barrier() or cpu_relax(). >>>> For most