Re: [Xen-devel] [PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

On 14/02/17 14:46, Waiman Long wrote: > On 02/14/2017 04:39 AM, Peter Zijlstra wrote: >> On Mon, Feb 13, 2017 at 05:34:01PM -0500, Waiman Long wrote: >>> It is the address of _time that will exceed the 32-bit limit. >> That seems extremely unlikely. That would mean we have more than 4G >> worth of

Re: [Xen-devel] [PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

On 14/02/17 14:46, Waiman Long wrote: > On 02/14/2017 04:39 AM, Peter Zijlstra wrote: >> On Mon, Feb 13, 2017 at 05:34:01PM -0500, Waiman Long wrote: >>> It is the address of _time that will exceed the 32-bit limit. >> That seems extremely unlikely. That would mean we have more than 4G >> worth of

Re: [PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

On Tue, Feb 14, 2017 at 09:46:17AM -0500, Waiman Long wrote: > On 02/14/2017 04:39 AM, Peter Zijlstra wrote: > > On Mon, Feb 13, 2017 at 05:34:01PM -0500, Waiman Long wrote: > >> It is the address of _time that will exceed the 32-bit limit. > > That seems extremely unlikely. That would mean we

Re: [PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

On Tue, Feb 14, 2017 at 09:46:17AM -0500, Waiman Long wrote: > On 02/14/2017 04:39 AM, Peter Zijlstra wrote: > > On Mon, Feb 13, 2017 at 05:34:01PM -0500, Waiman Long wrote: > >> It is the address of _time that will exceed the 32-bit limit. > > That seems extremely unlikely. That would mean we

Re: [PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

On 02/14/2017 04:39 AM, Peter Zijlstra wrote: > On Mon, Feb 13, 2017 at 05:34:01PM -0500, Waiman Long wrote: >> It is the address of _time that will exceed the 32-bit limit. > That seems extremely unlikely. That would mean we have more than 4G > worth of per-cpu variables declared in the kernel.

Re: [PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

On 02/14/2017 04:39 AM, Peter Zijlstra wrote: > On Mon, Feb 13, 2017 at 05:34:01PM -0500, Waiman Long wrote: >> It is the address of _time that will exceed the 32-bit limit. > That seems extremely unlikely. That would mean we have more than 4G > worth of per-cpu variables declared in the kernel.

Re: [PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

On Mon, Feb 13, 2017 at 05:34:01PM -0500, Waiman Long wrote: > It is the address of _time that will exceed the 32-bit limit. That seems extremely unlikely. That would mean we have more than 4G worth of per-cpu variables declared in the kernel.

Re: [PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

On Mon, Feb 13, 2017 at 05:34:01PM -0500, Waiman Long wrote: > It is the address of _time that will exceed the 32-bit limit. That seems extremely unlikely. That would mean we have more than 4G worth of per-cpu variables declared in the kernel.

Re: [PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

On February 13, 2017 2:34:01 PM PST, Waiman Long wrote: >On 02/13/2017 04:52 PM, Peter Zijlstra wrote: >> On Mon, Feb 13, 2017 at 03:12:45PM -0500, Waiman Long wrote: >>> On 02/13/2017 02:42 PM, Waiman Long wrote: On 02/13/2017 05:53 AM, Peter Zijlstra wrote: > On

Re: [PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

On February 13, 2017 2:34:01 PM PST, Waiman Long wrote: >On 02/13/2017 04:52 PM, Peter Zijlstra wrote: >> On Mon, Feb 13, 2017 at 03:12:45PM -0500, Waiman Long wrote: >>> On 02/13/2017 02:42 PM, Waiman Long wrote: On 02/13/2017 05:53 AM, Peter Zijlstra wrote: > On Mon, Feb 13, 2017 at

Re: [PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

On 02/13/2017 04:52 PM, Peter Zijlstra wrote: > On Mon, Feb 13, 2017 at 03:12:45PM -0500, Waiman Long wrote: >> On 02/13/2017 02:42 PM, Waiman Long wrote: >>> On 02/13/2017 05:53 AM, Peter Zijlstra wrote: On Mon, Feb 13, 2017 at 11:47:16AM +0100, Peter Zijlstra wrote: > That way we'd end

Re: [PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

On 02/13/2017 04:52 PM, Peter Zijlstra wrote: > On Mon, Feb 13, 2017 at 03:12:45PM -0500, Waiman Long wrote: >> On 02/13/2017 02:42 PM, Waiman Long wrote: >>> On 02/13/2017 05:53 AM, Peter Zijlstra wrote: On Mon, Feb 13, 2017 at 11:47:16AM +0100, Peter Zijlstra wrote: > That way we'd end

Re: [PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

On Mon, Feb 13, 2017 at 05:24:36PM -0500, Waiman Long wrote: > >> movsql %edi, %rax; > >> movq __per_cpu_offset(,%rax,8), %rax; > >> cmpb $0, %[offset](%rax); > >> setne %al; > I have thought of that too. However, the goal is to eliminate memory > read/write from/to stack. Eliminating a register

Re: [PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

On Mon, Feb 13, 2017 at 05:24:36PM -0500, Waiman Long wrote: > >> movsql %edi, %rax; > >> movq __per_cpu_offset(,%rax,8), %rax; > >> cmpb $0, %[offset](%rax); > >> setne %al; > I have thought of that too. However, the goal is to eliminate memory > read/write from/to stack. Eliminating a register

Re: [PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

On 02/13/2017 03:06 PM, h...@zytor.com wrote: > On February 13, 2017 2:53:43 AM PST, Peter Zijlstra > wrote: >> On Mon, Feb 13, 2017 at 11:47:16AM +0100, Peter Zijlstra wrote: >>> That way we'd end up with something like: >>> >>> asm(" >>> push %rdi; >>> movslq %edi, %rdi;

Re: [PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

On 02/13/2017 03:06 PM, h...@zytor.com wrote: > On February 13, 2017 2:53:43 AM PST, Peter Zijlstra > wrote: >> On Mon, Feb 13, 2017 at 11:47:16AM +0100, Peter Zijlstra wrote: >>> That way we'd end up with something like: >>> >>> asm(" >>> push %rdi; >>> movslq %edi, %rdi; >>> movq

Re: [PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

On February 13, 2017 1:52:20 PM PST, Peter Zijlstra wrote: >On Mon, Feb 13, 2017 at 03:12:45PM -0500, Waiman Long wrote: >> On 02/13/2017 02:42 PM, Waiman Long wrote: >> > On 02/13/2017 05:53 AM, Peter Zijlstra wrote: >> >> On Mon, Feb 13, 2017 at 11:47:16AM +0100, Peter

Re: [PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

On February 13, 2017 1:52:20 PM PST, Peter Zijlstra wrote: >On Mon, Feb 13, 2017 at 03:12:45PM -0500, Waiman Long wrote: >> On 02/13/2017 02:42 PM, Waiman Long wrote: >> > On 02/13/2017 05:53 AM, Peter Zijlstra wrote: >> >> On Mon, Feb 13, 2017 at 11:47:16AM +0100, Peter Zijlstra wrote: >> >>>

Re: [PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

On February 13, 2017 1:52:20 PM PST, Peter Zijlstra wrote: >On Mon, Feb 13, 2017 at 03:12:45PM -0500, Waiman Long wrote: >> On 02/13/2017 02:42 PM, Waiman Long wrote: >> > On 02/13/2017 05:53 AM, Peter Zijlstra wrote: >> >> On Mon, Feb 13, 2017 at 11:47:16AM +0100, Peter

Re: [PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

On February 13, 2017 1:52:20 PM PST, Peter Zijlstra wrote: >On Mon, Feb 13, 2017 at 03:12:45PM -0500, Waiman Long wrote: >> On 02/13/2017 02:42 PM, Waiman Long wrote: >> > On 02/13/2017 05:53 AM, Peter Zijlstra wrote: >> >> On Mon, Feb 13, 2017 at 11:47:16AM +0100, Peter Zijlstra wrote: >> >>>

Re: [PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

On Mon, Feb 13, 2017 at 12:06:44PM -0800, h...@zytor.com wrote: > >Maybe: > > > >movsql %edi, %rax; > >movq __per_cpu_offset(,%rax,8), %rax; > >cmpb $0, %[offset](%rax); > >setne %al; > > > >? > > We could kill the zero or sign extend by changing the calling > interface to pass an unsigned long

Re: [PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

On Mon, Feb 13, 2017 at 12:06:44PM -0800, h...@zytor.com wrote: > >Maybe: > > > >movsql %edi, %rax; > >movq __per_cpu_offset(,%rax,8), %rax; > >cmpb $0, %[offset](%rax); > >setne %al; > > > >? > > We could kill the zero or sign extend by changing the calling > interface to pass an unsigned long

Re: [PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

On Mon, Feb 13, 2017 at 03:12:45PM -0500, Waiman Long wrote: > On 02/13/2017 02:42 PM, Waiman Long wrote: > > On 02/13/2017 05:53 AM, Peter Zijlstra wrote: > >> On Mon, Feb 13, 2017 at 11:47:16AM +0100, Peter Zijlstra wrote: > >>> That way we'd end up with something like: > >>> > >>> asm(" > >>>

Re: [PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

On Mon, Feb 13, 2017 at 03:12:45PM -0500, Waiman Long wrote: > On 02/13/2017 02:42 PM, Waiman Long wrote: > > On 02/13/2017 05:53 AM, Peter Zijlstra wrote: > >> On Mon, Feb 13, 2017 at 11:47:16AM +0100, Peter Zijlstra wrote: > >>> That way we'd end up with something like: > >>> > >>> asm(" > >>>

Re: [PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

On February 13, 2017 2:53:43 AM PST, Peter Zijlstra wrote: >On Mon, Feb 13, 2017 at 11:47:16AM +0100, Peter Zijlstra wrote: >> That way we'd end up with something like: >> >> asm(" >> push %rdi; >> movslq %edi, %rdi; >> movq __per_cpu_offset(,%rdi,8), %rax; >> cmpb $0,

Re: [PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

On February 13, 2017 2:53:43 AM PST, Peter Zijlstra wrote: >On Mon, Feb 13, 2017 at 11:47:16AM +0100, Peter Zijlstra wrote: >> That way we'd end up with something like: >> >> asm(" >> push %rdi; >> movslq %edi, %rdi; >> movq __per_cpu_offset(,%rdi,8), %rax; >> cmpb $0, %[offset](%rax); >> setne

Re: [PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

On 02/13/2017 02:42 PM, Waiman Long wrote: > On 02/13/2017 05:53 AM, Peter Zijlstra wrote: >> On Mon, Feb 13, 2017 at 11:47:16AM +0100, Peter Zijlstra wrote: >>> That way we'd end up with something like: >>> >>> asm(" >>> push %rdi; >>> movslq %edi, %rdi; >>> movq __per_cpu_offset(,%rdi,8), %rax;

Re: [PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

On 02/13/2017 02:42 PM, Waiman Long wrote: > On 02/13/2017 05:53 AM, Peter Zijlstra wrote: >> On Mon, Feb 13, 2017 at 11:47:16AM +0100, Peter Zijlstra wrote: >>> That way we'd end up with something like: >>> >>> asm(" >>> push %rdi; >>> movslq %edi, %rdi; >>> movq __per_cpu_offset(,%rdi,8), %rax;

Re: [PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

On 02/13/2017 05:53 AM, Peter Zijlstra wrote: > On Mon, Feb 13, 2017 at 11:47:16AM +0100, Peter Zijlstra wrote: >> That way we'd end up with something like: >> >> asm(" >> push %rdi; >> movslq %edi, %rdi; >> movq __per_cpu_offset(,%rdi,8), %rax; >> cmpb $0, %[offset](%rax); >> setne %al; >> pop

Re: [PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

On 02/13/2017 05:53 AM, Peter Zijlstra wrote: > On Mon, Feb 13, 2017 at 11:47:16AM +0100, Peter Zijlstra wrote: >> That way we'd end up with something like: >> >> asm(" >> push %rdi; >> movslq %edi, %rdi; >> movq __per_cpu_offset(,%rdi,8), %rax; >> cmpb $0, %[offset](%rax); >> setne %al; >> pop

Re: [PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

On 02/13/2017 05:47 AM, Peter Zijlstra wrote: > On Fri, Feb 10, 2017 at 12:00:43PM -0500, Waiman Long wrote: > +asm( +".pushsection .text;" +".global __raw_callee_save___kvm_vcpu_is_preempted;" +".type __raw_callee_save___kvm_vcpu_is_preempted, @function;"

Re: [PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

On 02/13/2017 05:47 AM, Peter Zijlstra wrote: > On Fri, Feb 10, 2017 at 12:00:43PM -0500, Waiman Long wrote: > +asm( +".pushsection .text;" +".global __raw_callee_save___kvm_vcpu_is_preempted;" +".type __raw_callee_save___kvm_vcpu_is_preempted, @function;"

Re: [PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

On Mon, Feb 13, 2017 at 11:47:16AM +0100, Peter Zijlstra wrote: > That way we'd end up with something like: > > asm(" > push %rdi; > movslq %edi, %rdi; > movq __per_cpu_offset(,%rdi,8), %rax; > cmpb $0, %[offset](%rax); > setne %al; > pop %rdi; > " : : [offset] "i" (((unsigned long)_time) +

Re: [PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

On Mon, Feb 13, 2017 at 11:47:16AM +0100, Peter Zijlstra wrote: > That way we'd end up with something like: > > asm(" > push %rdi; > movslq %edi, %rdi; > movq __per_cpu_offset(,%rdi,8), %rax; > cmpb $0, %[offset](%rax); > setne %al; > pop %rdi; > " : : [offset] "i" (((unsigned long)_time) +

Re: [PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

On Fri, Feb 10, 2017 at 12:00:43PM -0500, Waiman Long wrote: > >> +asm( > >> +".pushsection .text;" > >> +".global __raw_callee_save___kvm_vcpu_is_preempted;" > >> +".type __raw_callee_save___kvm_vcpu_is_preempted, @function;" > >> +"__raw_callee_save___kvm_vcpu_is_preempted:" > >> +FRAME_BEGIN >

Re: [PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

On Fri, Feb 10, 2017 at 12:00:43PM -0500, Waiman Long wrote: > >> +asm( > >> +".pushsection .text;" > >> +".global __raw_callee_save___kvm_vcpu_is_preempted;" > >> +".type __raw_callee_save___kvm_vcpu_is_preempted, @function;" > >> +"__raw_callee_save___kvm_vcpu_is_preempted:" > >> +FRAME_BEGIN >

Re: [PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

On 02/10/2017 11:19 AM, Peter Zijlstra wrote: > On Fri, Feb 10, 2017 at 10:43:09AM -0500, Waiman Long wrote: >> It was found when running fio sequential write test with a XFS ramdisk >> on a VM running on a 2-socket x86-64 system, the %CPU times as reported >> by perf were as follows: >> >>

Re: [PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

On 02/10/2017 11:19 AM, Peter Zijlstra wrote: > On Fri, Feb 10, 2017 at 10:43:09AM -0500, Waiman Long wrote: >> It was found when running fio sequential write test with a XFS ramdisk >> on a VM running on a 2-socket x86-64 system, the %CPU times as reported >> by perf were as follows: >> >>

Re: [PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

On 02/10/2017 11:35 AM, Waiman Long wrote: > On 02/10/2017 11:19 AM, Peter Zijlstra wrote: >> On Fri, Feb 10, 2017 at 10:43:09AM -0500, Waiman Long wrote: >>> It was found when running fio sequential write test with a XFS ramdisk >>> on a VM running on a 2-socket x86-64 system, the %CPU times as

Re: [PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

On 02/10/2017 11:35 AM, Waiman Long wrote: > On 02/10/2017 11:19 AM, Peter Zijlstra wrote: >> On Fri, Feb 10, 2017 at 10:43:09AM -0500, Waiman Long wrote: >>> It was found when running fio sequential write test with a XFS ramdisk >>> on a VM running on a 2-socket x86-64 system, the %CPU times as

Re: [PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

On 10/02/2017 16:43, Waiman Long wrote: > It was found when running fio sequential write test with a XFS ramdisk > on a VM running on a 2-socket x86-64 system, the %CPU times as reported > by perf were as follows: > > 69.75% 0.59% fio [k] down_write > 69.15% 0.01% fio [k]

Re: [PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

On 10/02/2017 16:43, Waiman Long wrote: > It was found when running fio sequential write test with a XFS ramdisk > on a VM running on a 2-socket x86-64 system, the %CPU times as reported > by perf were as follows: > > 69.75% 0.59% fio [k] down_write > 69.15% 0.01% fio [k]

Re: [PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

On Fri, Feb 10, 2017 at 10:43:09AM -0500, Waiman Long wrote: > It was found when running fio sequential write test with a XFS ramdisk > on a VM running on a 2-socket x86-64 system, the %CPU times as reported > by perf were as follows: > > 69.75% 0.59% fio [k] down_write > 69.15% 0.01% fio

Re: [PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

On Fri, Feb 10, 2017 at 10:43:09AM -0500, Waiman Long wrote: > It was found when running fio sequential write test with a XFS ramdisk > on a VM running on a 2-socket x86-64 system, the %CPU times as reported > by perf were as follows: > > 69.75% 0.59% fio [k] down_write > 69.15% 0.01% fio

[PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

It was found when running fio sequential write test with a XFS ramdisk on a VM running on a 2-socket x86-64 system, the %CPU times as reported by perf were as follows: 69.75% 0.59% fio [k] down_write 69.15% 0.01% fio [k] call_rwsem_down_write_failed 67.12% 1.12% fio [k]

[PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function

It was found when running fio sequential write test with a XFS ramdisk on a VM running on a 2-socket x86-64 system, the %CPU times as reported by perf were as follows: 69.75% 0.59% fio [k] down_write 69.15% 0.01% fio [k] call_rwsem_down_write_failed 67.12% 1.12% fio [k]