search for: preempt

Hi, I would like to know about which threads will be preempted by which on my OpenSolaris machine. Therefore, I ran a multithreaded program "myprogram" with 32 threads on my 24-core Solaris machine. I make sure that each thread of my program has same priority (priority zero), so that we can reduce priority inversions (saving preemptions -- system...

From: Pan Xinhui > Sent: 20 October 2016 22:28 > Commit ("x86, kvm: support vcpu preempted check") add one field "__u8 > preempted" into struct kvm_steal_time. This field tells if one vcpu is > running or not. > > It is zero if 1) some old KVM deos not support this filed. 2) the vcpu is > preempted. Other values means the vcpu has been preempted. > &g...

From: Pan Xinhui > Sent: 20 October 2016 22:28 > Commit ("x86, kvm: support vcpu preempted check") add one field "__u8 > preempted" into struct kvm_steal_time. This field tells if one vcpu is > running or not. > > It is zero if 1) some old KVM deos not support this filed. 2) the vcpu is > preempted. Other values means the vcpu has been preempted. > &g...

On Thu, Oct 20, 2016 at 05:27:54PM -0400, Pan Xinhui wrote: > Commit ("x86, kvm: support vcpu preempted check") add one field "__u8 > preempted" into struct kvm_steal_time. This field tells if one vcpu is > running or not. > > It is zero if 1) some old KVM deos not support this filed. 2) the vcpu is > preempted. Other values means the vcpu has been preempted. ^^^^^^...

On Thu, Oct 20, 2016 at 05:27:54PM -0400, Pan Xinhui wrote: > Commit ("x86, kvm: support vcpu preempted check") add one field "__u8 > preempted" into struct kvm_steal_time. This field tells if one vcpu is > running or not. > > It is zero if 1) some old KVM deos not support this filed. 2) the vcpu is > preempted. Other values means the vcpu has been preempted. ^^^^^^...

On Thu, Jul 07, 2016 at 04:48:05PM +0800, Wanpeng Li wrote: > 2016-07-06 20:28 GMT+08:00 Paolo Bonzini <pbonzini at redhat.com>: > > Hmm, you're right. We can use bit 0 of struct kvm_steal_time's flags to > > indicate that pad[0] is a "VCPU preempted" field; if pad[0] is 1, the > > VCPU has been scheduled out since the last time the guest reset the bit. > > The guest can use an xchg to test-and-clear it. The bit can be > > accessed at any time, independent of the version field. > > If one vCPU is preempted, and...

On Thu, Jul 07, 2016 at 04:48:05PM +0800, Wanpeng Li wrote: > 2016-07-06 20:28 GMT+08:00 Paolo Bonzini <pbonzini at redhat.com>: > > Hmm, you're right. We can use bit 0 of struct kvm_steal_time's flags to > > indicate that pad[0] is a "VCPU preempted" field; if pad[0] is 1, the > > VCPU has been scheduled out since the last time the guest reset the bit. > > The guest can use an xchg to test-and-clear it. The bit can be > > accessed at any time, independent of the version field. > > If one vCPU is preempted, and...

change from v4: spilt x86 kvm vcpu preempted check into two patches. add documentation patch. add x86 vcpu preempted check patch under xen add s390 vcpu preempted check patch change from v3: add x86 vcpu preempted check patch change from v2: no code change, fix typos, update some comments change from v1: a simplier definition of defa...

change from v4: spilt x86 kvm vcpu preempted check into two patches. add documentation patch. add x86 vcpu preempted check patch under xen add s390 vcpu preempted check patch change from v3: add x86 vcpu preempted check patch change from v2: no code change, fix typos, update some comments change from v1: a simplier definition of defa...

On 21/10/2016 20:39, rkrcmar at redhat.com wrote: > 2016-10-21 11:27+0000, David Laight: >> From: Pan Xinhui >>> Sent: 20 October 2016 22:28 >>> Commit ("x86, kvm: support vcpu preempted check") add one field "__u8 >>> preempted" into struct kvm_steal_time. This field tells if one vcpu is >>> running or not. >>> >>> It is zero if 1) some old KVM deos not support this filed. 2) the vcpu is >>> preempted. Other values mean...

On 21/10/2016 20:39, rkrcmar at redhat.com wrote: > 2016-10-21 11:27+0000, David Laight: >> From: Pan Xinhui >>> Sent: 20 October 2016 22:28 >>> Commit ("x86, kvm: support vcpu preempted check") add one field "__u8 >>> preempted" into struct kvm_steal_time. This field tells if one vcpu is >>> running or not. >>> >>> It is zero if 1) some old KVM deos not support this filed. 2) the vcpu is >>> preempted. Other values mean...

change from v5: spilt x86/kvm patch into guest/host part. introduce kvm_write_guest_offset_cached. fix some typos. rebase patch onto 4.9.2 change from v4: spilt x86 kvm vcpu preempted check into two patches. add documentation patch. add x86 vcpu preempted check patch under xen add s390 vcpu preempted check patch change from v3: add x86 vcpu preempted check patch change from v2: no code change, fix typos, update some comments change from v1: a simplier definition of defa...

change from v5: spilt x86/kvm patch into guest/host part. introduce kvm_write_guest_offset_cached. fix some typos. rebase patch onto 4.9.2 change from v4: spilt x86 kvm vcpu preempted check into two patches. add documentation patch. add x86 vcpu preempted check patch under xen add s390 vcpu preempted check patch change from v3: add x86 vcpu preempted check patch change from v2: no code change, fix typos, update some comments change from v1: a simplier definition of defa...

...g>: > On Thu, Jul 07, 2016 at 04:48:05PM +0800, Wanpeng Li wrote: >> 2016-07-06 20:28 GMT+08:00 Paolo Bonzini <pbonzini at redhat.com>: >> > Hmm, you're right. We can use bit 0 of struct kvm_steal_time's flags to >> > indicate that pad[0] is a "VCPU preempted" field; if pad[0] is 1, the >> > VCPU has been scheduled out since the last time the guest reset the bit. >> > The guest can use an xchg to test-and-clear it. The bit can be >> > accessed at any time, independent of the version field. >> >> If one vCP...

Commit ("x86, kvm: support vcpu preempted check") add one field "__u8 preempted" into struct kvm_steal_time. This field tells if one vcpu is running or not. It is zero if 1) some old KVM deos not support this filed. 2) the vcpu is preempted. Other values means the vcpu has been preempted. Signed-off-by: Pan Xinhui <xi...

Support the vcpu_is_preempted() functionality under KVM. This will enhance lock performance on overcommitted hosts (more runnable vcpus than physical cpus in the system) as doing busy waits for preempted vcpus will hurt system performance far worse than early yielding. Use one field of struct kvm_steal_time ::preempted to in...

On Fri, Oct 28, 2016 at 04:11:16AM -0400, Pan Xinhui wrote: > change from v5: > spilt x86/kvm patch into guest/host part. > introduce kvm_write_guest_offset_cached. > fix some typos. > rebase patch onto 4.9.2 > change from v4: > spilt x86 kvm vcpu preempted check into two patches. > add documentation patch. > add x86 vcpu preempted check patch under xen > add s390 vcpu preempted check patch > change from v3: > add x86 vcpu preempted check patch > change from v2: > no code change, fix typos, update some comments > change...

...On Thu, Jul 07, 2016 at 04:48:05PM +0800, Wanpeng Li wrote: >>> 2016-07-06 20:28 GMT+08:00 Paolo Bonzini <pbonzini at redhat.com>: >>> > Hmm, you're right. We can use bit 0 of struct kvm_steal_time's flags to >>> > indicate that pad[0] is a "VCPU preempted" field; if pad[0] is 1, the >>> > VCPU has been scheduled out since the last time the guest reset the bit. >>> > The guest can use an xchg to test-and-clear it. The bit can be >>> > accessed at any time, independent of the version field. >>> &gt...

...On Thu, Jul 07, 2016 at 04:48:05PM +0800, Wanpeng Li wrote: >>> 2016-07-06 20:28 GMT+08:00 Paolo Bonzini <pbonzini at redhat.com>: >>> > Hmm, you're right. We can use bit 0 of struct kvm_steal_time's flags to >>> > indicate that pad[0] is a "VCPU preempted" field; if pad[0] is 1, the >>> > VCPU has been scheduled out since the last time the guest reset the bit. >>> > The guest can use an xchg to test-and-clear it. The bit can be >>> > accessed at any time, independent of the version field. >>> &gt...

Hi Samba gurus, need your suggestions on where to plant debug code in Linux kernel to stomp on a bug. Please read on: > I narrowed down Samba weirdness I observe on 2.4.10 to preempt patch. > Plain 2.4.10 works fine, 2.4.10+preempt (with latency measurement > turned on) is sometimes oopses, and sometimes reports 'file already > exists' when I attempt to copy a file from WinNT box to Linux. > Sometimes it works ok (roughly 50% failure rate) 2.4.13+preempt ex...