From: xinhui <xinhui.pan@linux.vnet.ibm.com> To: Wanpeng Li <kernellwp@gmail.com> Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, linuxppc-dev@lists.ozlabs.org, virtualization@lists.linux-foundation.org, linux-s390 <linux-s390@vger.kernel.org>, Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@redhat.com>, mpe@ellerman.id.au, Paul Mackerras <paulus@samba.org>, benh@kernel.crashing.org, Paul McKenney <paulmck@linux.vnet.ibm.com>, Waiman Long <waiman.long@hpe.com>, will.deacon@arm.com, boqun.feng@gmail.com, Davidlohr Bueso <dave@stgolabs.net>, schwidefsky@de.ibm.com Subject: Re: [PATCH v2 2/4] powerpc/spinlock: support vcpu preempted check Date: Wed, 06 Jul 2016 12:58:11 +0800 [thread overview] Message-ID: <577C8FE3.3010208@linux.vnet.ibm.com> (raw) In-Reply-To: <CANRm+CxQMSrg69p2Xey829Mz4Au9YCai+4JD17i9urdbj0VgkQ@mail.gmail.com> Hi, wanpeng On 2016年07月05日 17:57, Wanpeng Li wrote: > Hi Xinhui, > 2016-06-28 22:43 GMT+08:00 Pan Xinhui <xinhui.pan@linux.vnet.ibm.com>: >> This is to fix some lock holder preemption issues. Some other locks >> implementation do a spin loop before acquiring the lock itself. Currently >> kernel has an interface of bool vcpu_is_preempted(int cpu). It take the cpu >> as parameter and return true if the cpu is preempted. Then kernel can break >> the spin loops upon on the retval of vcpu_is_preempted. >> >> As kernel has used this interface, So lets support it. >> >> Only pSeries need supoort it. And the fact is powerNV are built into same >> kernel image with pSeries. So we need return false if we are runnig as >> powerNV. The another fact is that lppaca->yiled_count keeps zero on >> powerNV. So we can just skip the machine type. > > Lock holder vCPU preemption can be detected by hardware pSeries or > paravirt method? > There is one shard struct between kernel and powerVM/KVM. And we read the yield_count of this struct to detect if one vcpu is running or not. SO it's easy for ppc to implement such interface. Note that yield_count is set by powerVM/KVM. and only pSeries can run a guest for now. :) I also review x86 related code, looks like we need add one hyer-call to get such vcpu preemption info? thanks xinui > Regards, > Wanpeng Li >
WARNING: multiple messages have this Message-ID (diff)
From: xinhui <xinhui.pan@linux.vnet.ibm.com> To: Wanpeng Li <kernellwp@gmail.com> Cc: linux-s390 <linux-s390@vger.kernel.org>, Davidlohr Bueso <dave@stgolabs.net>, Peter Zijlstra <peterz@infradead.org>, mpe@ellerman.id.au, boqun.feng@gmail.com, will.deacon@arm.com, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, Waiman Long <waiman.long@hpe.com>, virtualization@lists.linux-foundation.org, Ingo Molnar <mingo@redhat.com>, Paul Mackerras <paulus@samba.org>, benh@kernel.crashing.org, schwidefsky@de.ibm.com, Paul McKenney <paulmck@linux.vnet.ibm.com>, linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCH v2 2/4] powerpc/spinlock: support vcpu preempted check Date: Wed, 06 Jul 2016 12:58:11 +0800 [thread overview] Message-ID: <577C8FE3.3010208@linux.vnet.ibm.com> (raw) In-Reply-To: <CANRm+CxQMSrg69p2Xey829Mz4Au9YCai+4JD17i9urdbj0VgkQ@mail.gmail.com> Hi, wanpeng On 2016年07月05日 17:57, Wanpeng Li wrote: > Hi Xinhui, > 2016-06-28 22:43 GMT+08:00 Pan Xinhui <xinhui.pan@linux.vnet.ibm.com>: >> This is to fix some lock holder preemption issues. Some other locks >> implementation do a spin loop before acquiring the lock itself. Currently >> kernel has an interface of bool vcpu_is_preempted(int cpu). It take the cpu >> as parameter and return true if the cpu is preempted. Then kernel can break >> the spin loops upon on the retval of vcpu_is_preempted. >> >> As kernel has used this interface, So lets support it. >> >> Only pSeries need supoort it. And the fact is powerNV are built into same >> kernel image with pSeries. So we need return false if we are runnig as >> powerNV. The another fact is that lppaca->yiled_count keeps zero on >> powerNV. So we can just skip the machine type. > > Lock holder vCPU preemption can be detected by hardware pSeries or > paravirt method? > There is one shard struct between kernel and powerVM/KVM. And we read the yield_count of this struct to detect if one vcpu is running or not. SO it's easy for ppc to implement such interface. Note that yield_count is set by powerVM/KVM. and only pSeries can run a guest for now. :) I also review x86 related code, looks like we need add one hyer-call to get such vcpu preemption info? thanks xinui > Regards, > Wanpeng Li > _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
next prev parent reply other threads:[~2016-07-06 4:58 UTC|newest] Thread overview: 77+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-06-28 14:43 [PATCH v2 0/4] implement vcpu preempted check Pan Xinhui 2016-06-28 14:43 ` Pan Xinhui 2016-06-28 14:43 ` [PATCH v2 1/4] kernel/sched: introduce vcpu preempted check interface Pan Xinhui 2016-06-28 14:43 ` Pan Xinhui 2016-06-28 14:43 ` [PATCH v2 2/4] powerpc/spinlock: support vcpu preempted check Pan Xinhui 2016-06-28 14:43 ` Pan Xinhui 2016-07-05 9:57 ` Wanpeng Li 2016-07-05 9:57 ` Wanpeng Li 2016-07-06 4:58 ` xinhui [this message] 2016-07-06 4:58 ` xinhui 2016-07-06 6:46 ` Wanpeng Li 2016-07-06 6:46 ` Wanpeng Li 2016-07-06 6:46 ` Wanpeng Li 2016-07-06 7:58 ` Peter Zijlstra 2016-07-06 7:58 ` Peter Zijlstra 2016-07-06 8:32 ` Wanpeng Li 2016-07-06 8:32 ` Wanpeng Li 2016-07-06 10:18 ` xinhui 2016-07-06 10:18 ` xinhui 2016-07-06 10:54 ` Balbir Singh 2016-07-06 10:54 ` Balbir Singh 2016-07-06 10:54 ` Balbir Singh 2016-07-15 15:35 ` Pan Xinhui 2016-07-15 15:35 ` Pan Xinhui 2016-06-28 14:43 ` [PATCH v2 3/4] locking/osq: Drop the overload of osq_lock() Pan Xinhui 2016-06-28 14:43 ` Pan Xinhui 2016-06-28 14:43 ` [PATCH v2 4/4] kernel/locking: Drop the overload of {mutex,rwsem}_spin_on_owner Pan Xinhui 2016-06-28 14:43 ` [PATCH v2 4/4] kernel/locking: Drop the overload of {mutex, rwsem}_spin_on_owner Pan Xinhui 2016-06-28 14:43 ` Pan Xinhui 2016-07-06 6:52 ` [PATCH v2 0/4] implement vcpu preempted check Peter Zijlstra 2016-07-06 6:52 ` Peter Zijlstra 2016-07-06 7:47 ` Juergen Gross 2016-07-06 7:47 ` Juergen Gross 2016-07-06 8:19 ` Peter Zijlstra 2016-07-06 8:19 ` Peter Zijlstra 2016-07-06 8:38 ` Juergen Gross 2016-07-06 8:38 ` Juergen Gross 2016-07-06 12:44 ` Paolo Bonzini 2016-07-06 12:44 ` Paolo Bonzini 2016-07-06 16:56 ` Christian Borntraeger 2016-07-06 16:56 ` Christian Borntraeger 2016-07-06 16:56 ` Christian Borntraeger 2016-07-06 10:05 ` xinhui 2016-07-06 10:05 ` xinhui 2016-07-06 10:44 ` Paolo Bonzini 2016-07-06 11:59 ` Peter Zijlstra 2016-07-06 11:59 ` Peter Zijlstra 2016-07-06 12:08 ` Wanpeng Li 2016-07-06 12:08 ` Wanpeng Li 2016-07-06 12:28 ` Paolo Bonzini 2016-07-06 12:28 ` Paolo Bonzini 2016-07-06 13:03 ` Wanpeng Li 2016-07-06 13:03 ` Wanpeng Li 2016-07-07 8:48 ` Wanpeng Li 2016-07-07 8:48 ` Wanpeng Li 2016-07-07 9:42 ` Peter Zijlstra 2016-07-07 9:42 ` Peter Zijlstra 2016-07-07 10:12 ` Wanpeng Li 2016-07-07 10:12 ` Wanpeng Li 2016-07-07 10:27 ` Wanpeng Li 2016-07-07 10:27 ` Wanpeng Li 2016-07-07 11:15 ` Peter Zijlstra 2016-07-07 11:15 ` Peter Zijlstra 2016-07-07 11:08 ` Peter Zijlstra 2016-07-07 11:08 ` Peter Zijlstra 2016-07-07 11:09 ` Peter Zijlstra 2016-07-07 11:09 ` Peter Zijlstra 2016-07-07 11:21 ` Peter Zijlstra 2016-07-07 11:21 ` Peter Zijlstra 2016-07-11 15:10 ` Waiman Long 2016-07-11 15:10 ` Waiman Long 2016-07-11 15:10 ` Waiman Long 2016-07-12 4:16 ` Juergen Gross 2016-07-12 4:16 ` Juergen Gross 2016-07-12 18:16 ` Waiman Long 2016-07-12 18:16 ` Waiman Long 2016-07-12 18:16 ` Waiman Long
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