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From: Anthony Liguori <anthony@codemonkey.ws>
To: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Ulrich Obergfell <uobergfe@redhat.com>,
	Glauber Costa <glommer@redhat.com>, Avi Kivity <avi@redhat.com>,
	kvm <kvm@vger.kernel.org>, qemu-devel <qemu-devel@nongnu.org>
Subject: Re: [Qemu-devel] Re: [RFC: 0/2] patch for QEMU HPET periodic timer emulation to alleviate time drift
Date: Mon, 07 Feb 2011 08:28:48 -0600	[thread overview]
Message-ID: <4D5001A0.8020503@codemonkey.ws> (raw)
In-Reply-To: <4D4FFD3B.2030903@siemens.com>

On 02/07/2011 08:10 AM, Jan Kiszka wrote:
> Again: please not in an ad-hoc fashion but as a generic services usable
> by _all_ periodic timer sources that want to implement compensation.
> This infrastructure should also be designed to once integrate IRQ
> coalescing information as well.
>
> The point why I'm insisting on a broader solution is that both sources
> for lost ticks (iothread and vcpu) end up in the same output: an
> adjustment of the injection frequency of the affected timer device.
> There is not "HPET" or "RTC" or "PIT" in this, all this may apply to the
> SoC timer of some emulated ARM board as well.
>    

Fair enough, how about:

typedef struct PeriodicTimer PeriodicTimer;

/**
  * @accumulated_ticks:  the number of unacknowledged ticks in total 
since the creation of the timer
  **/
typedef void (PeriodicTimer)(void *opaque, int accumulated_ticks);

PeriodicTimer *periodic_timer_new(PeriodicTimerFunc *cb, void *opaque);

void periodic_timer_mod(PeriodicTimer *timer, int64_t interval, TimeUnit 
unit);

/**
  * @policy: the drift catch-up policy
  *                DRIFT_COMP_FAST, deliver next tick as soon as any 
tick is acknowledged if accumulated_ticks > 1
  *                DRIFT_COMP_NONE, do not change interval regardless of 
accumulated ticks
  *                DRIFT_COMP_GRADUAL, shorten interval by half until 
accumulated_ticks <= 1
  */
void periodic_timer_set_policy(PeriodicTimer *timer, 
DriftCompensationPolicy policy);

/**
  * @ticks: number of ticks to acknowledge that are currently outstanding.
  **/
void periodic_timer_ack(PeriodicTimer *timer, int ticks);

Regards,

Anthony Liguori

> Jan
>
>    


  reply	other threads:[~2011-02-07 14:28 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <480481933.225059.1296734409954.JavaMail.root@zmail07.collab.prod.int.phx2.redhat.com>
2011-02-03 13:43 ` [RFC: 0/2] patch for QEMU HPET periodic timer emulation to alleviate time drift Ulrich Obergfell
2011-02-03 15:28   ` Jan Kiszka
2011-02-03 20:07     ` [Qemu-devel] " Anthony Liguori
2011-02-03 21:24       ` Jan Kiszka
2011-02-04  2:06         ` Anthony Liguori
2011-02-04  8:56           ` Jan Kiszka
2011-02-07 12:34             ` Avi Kivity
2011-02-07 13:11               ` Anthony Liguori
2011-02-07 13:14                 ` Avi Kivity
2011-02-07 13:23                   ` Anthony Liguori
2011-02-07 13:34                     ` Avi Kivity
2011-02-07 13:41                     ` Gleb Natapov
2011-02-07 13:46                       ` Avi Kivity
2011-02-07 13:48                         ` Gleb Natapov
2011-02-07 13:51                           ` Avi Kivity
2011-02-07 13:54                             ` Gleb Natapov
2011-02-07 14:10                     ` Jan Kiszka
2011-02-07 14:28                       ` Anthony Liguori [this message]
2011-02-07 14:43                         ` Jan Kiszka
2011-02-07 14:54                           ` Anthony Liguori
2011-02-07 14:57                             ` Jan Kiszka
2011-02-07 15:01                               ` Anthony Liguori
2011-02-07 15:08                                 ` Jan Kiszka
2011-02-07 15:13                                 ` Avi Kivity
2011-02-07 15:17                                   ` Jan Kiszka
2011-02-07 15:29                                     ` Avi Kivity
2011-02-07 19:30                                       ` Anthony Liguori
2011-02-08  9:11                                         ` Avi Kivity
2011-02-07 15:20                                   ` Jan Kiszka
2011-02-07 15:30                                     ` Avi Kivity
2011-02-07 19:28                                     ` Anthony Liguori
2011-02-07 14:58                             ` Avi Kivity
2011-02-07 15:01                               ` Jan Kiszka
2011-02-07 15:08                                 ` Avi Kivity
2011-02-07 15:14                                   ` Jan Kiszka
2011-02-07 15:16                                     ` Avi Kivity
2011-02-07 15:22                                   ` Anthony Liguori
2011-02-07 15:18                               ` Anthony Liguori
2011-02-04  9:52           ` Ulrich Obergfell
2011-02-07 10:44       ` Ulrich Obergfell
2011-02-07 13:24       ` Anthony Liguori

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