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From: Yi Sun <yi.y.sun@linux.intel.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Waiman Long <longman@redhat.com>, Juergen Gross <jgross@suse.com>,
	linux-kernel@vger.kernel.org, x86@kernel.org, tglx@linutronix.de,
	chao.p.peng@intel.com, chao.gao@intel.com,
	isaku.yamahata@intel.com, michael.h.kelley@microsoft.com,
	tianyu.lan@microsoft.com, "K. Y. Srinivasan" <kys@microsoft.com>,
	Haiyang Zhang <haiyangz@microsoft.com>,
	Stephen Hemminger <sthemmin@microsoft.com>,
	"mingo@redhat.com" <mingo@redhat.com>,
	Will Deacon <will.deacon@arm.com>
Subject: Re: [PATCH v1 2/2] x86/hyperv: make HvNotifyLongSpinWait hypercall
Date: Tue, 23 Oct 2018 10:57:40 +0800	[thread overview]
Message-ID: <20181023025740.GL11769@yi.y.sun> (raw)
In-Reply-To: <20181022171516.GH3117@worktop.programming.kicks-ass.net>

On 18-10-22 19:15:16, Peter Zijlstra wrote:
> 
> Firstly, who come a patch that is grubbing around in kernel/locking/ has
> an x86/hyperv subject and isn't Cc'ed to the locking maintainers?
> 
I am sorry. That is my fault to forget to add locking maintainers.

> On Mon, Oct 22, 2018 at 12:31:45PM -0400, Waiman Long wrote:
> > On 10/22/2018 03:32 AM, Juergen Gross wrote:
> > > On 22/10/2018 03:53, Yi Sun wrote:
> > >> On 18-10-19 16:20:52, Juergen Gross wrote:
> > >>> On 19/10/2018 15:13, Yi Sun wrote:
> > >> [...]
> > >>
> > >>>> diff --git a/kernel/locking/qspinlock_paravirt.h b/kernel/locking/qspinlock_paravirt.h
> > >>>> index 0130e48..9e88c7e 100644
> > >>>> --- a/kernel/locking/qspinlock_paravirt.h
> > >>>> +++ b/kernel/locking/qspinlock_paravirt.h
> > >>>> @@ -7,6 +7,8 @@
> > >>>>  #include <linux/bootmem.h>
> > >>>>  #include <linux/debug_locks.h>
> > >>>>  
> > >>>> +#include <asm/mshyperv.h>
> > >>>> +
> > >>>>  /*
> > >>>>   * Implement paravirt qspinlocks; the general idea is to halt the vcpus instead
> > >>>>   * of spinning them.
> > >>>> @@ -305,6 +307,10 @@ static void pv_wait_node(struct mcs_spinlock *node, struct mcs_spinlock *prev)
> > >>>>  				wait_early = true;
> > >>>>  				break;
> > >>>>  			}
> > >>>> +#if defined(CONFIG_X86_64) && defined(CONFIG_PARAVIRT_SPINLOCKS) && IS_ENABLED(CONFIG_HYPERV)
> > >>>> +			if (!hv_notify_long_spin_wait(SPIN_THRESHOLD - loop))
> > >>>> +				break;
> > >>>> +#endif
> 
> Secondly; how come you thought that was acceptable in any way shape or
> form?
> 
Sorry for that. Will try another way.

> > > vcpu_is_preempted() is already part of this loop. And this is a paravirt
> > > hook. Can't you make use of that? This might require adding another
> > > parameter to this hook, but I'd prefer that over another pv-spinlock
> > > hook.
> 
> > I agree with Juergen on that. I would suggest rename the
> > vcpu_is_preempted hook into a more generic vcpu_stop_spinning, perhaps,
> > so different hypervisors can act on the information accordingly. Adding
> > an extra parameter is fine.
> 
> No; no extra parameters. vcpu_is_preempted() is a simple and intuitive
> interface. Why would we want to make it complicated?

  parent reply	other threads:[~2018-10-23  3:00 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-19 13:13 [PATCH v1 0/2] Enable HvNotifyLongSpinWait for Hyper-V Yi Sun
2018-10-19 13:13 ` [PATCH v1 1/2] x86/hyperv: get spinlock retry number on Hyper-V Yi Sun
2018-10-19 13:13 ` [PATCH v1 2/2] x86/hyperv: make HvNotifyLongSpinWait hypercall Yi Sun
2018-10-19 14:20   ` Juergen Gross
2018-10-22  1:53     ` Yi Sun
2018-10-22  7:32       ` Juergen Gross
2018-10-22 16:31         ` Waiman Long
2018-10-22 17:15           ` Peter Zijlstra
2018-10-22 17:27             ` Waiman Long
2018-10-22 17:31               ` Peter Zijlstra
2018-10-22 18:01                 ` Waiman Long
2018-10-23  2:57             ` Yi Sun [this message]
2018-10-23  8:51               ` Peter Zijlstra
2018-10-23  9:33                 ` Yi Sun
2018-10-31  1:54                   ` Yi Sun
2018-10-31 14:10                     ` Peter Zijlstra
2018-10-31 15:07                       ` Waiman Long
2018-10-31 17:15                         ` Peter Zijlstra
2018-11-01  3:20                           ` Yi Sun
2018-11-01  8:59                             ` Peter Zijlstra
2018-11-01 12:59                             ` Waiman Long
2018-11-05  6:54                               ` Yi Sun
2018-10-24 16:53   ` Michael Kelley
2018-10-25  2:23     ` Yi Sun
2018-10-31  2:06     ` Yi Sun

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