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From: Yi Sun <yi.y.sun@linux.intel.com>
To: Juergen Gross <jgross@suse.com>
Cc: 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>
Subject: Re: [PATCH v1 2/2] x86/hyperv: make HvNotifyLongSpinWait hypercall
Date: Mon, 22 Oct 2018 09:53:42 +0800	[thread overview]
Message-ID: <20181022015342.GK11769@yi.y.sun> (raw)
In-Reply-To: <bab010e9-a122-95f1-d8cc-790e56c72716@suse.com>

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
> 
> I don't like that. Why should a KVM or Xen guest call into a hyperv
> specific function?
> 
> Can't you move this to existing hyperv specific paravirt hooks?
> 
hv_notify_long_spin_wait() must be called in this loop but it seems
there is no appropriate existing paravirt hook here. So, can I add
one more hook in pv_lock_ops to do this notification?

> 
> Juergen

  reply	other threads:[~2018-10-22  1:56 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 [this message]
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
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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