From: "Jason J. Herne" <jjherne@linux.vnet.ibm.com>
To: Paolo Bonzini <pbonzini@redhat.com>,
afaerber@suse.de, amit.shah@redhat.com, dgilbert@redhat.com,
borntraeger@de.ibm.com, quintela@redhat.com,
qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH v4 1/5] cpu: Provide vcpu throttling interface
Date: Fri, 31 Jul 2015 13:42:34 -0400 [thread overview]
Message-ID: <55BBB38A.4060807@linux.vnet.ibm.com> (raw)
In-Reply-To: <55BBAD5D.4090807@redhat.com>
On 07/31/2015 01:16 PM, Paolo Bonzini wrote:
>
>
> On 31/07/2015 19:12, Jason J. Herne wrote:
>>>
>>>
>>
>> Throttle ratio is relative to CPU_THROTTLE_TIMESLICE. Take a look at how
>> throttle_ratio is used in the calculation:
>>
>> long sleeptime_ms = (long)(throttle_ratio * CPU_THROTTLE_TIMESLICE);
>>
>> A value of 1 means we sleep the same amount of time that we execute.
>
> But that doesn't work if your timer runs every CPU_THROTTLE_TIMESLICE
> milliseconds, and thus schedules async work every CPU_THROTTLE_TIMESLICE
> milliseconds.
>
> The timer would have to be scheduled every (throttle_ratio + 1) *
> CPU_THROTTLE_TIMESLICE milliseconds, i.e. CPU_THROTTLE_TIMESLICE /
> (1-pct) milliseconds.
>
> Paolo
Doh! Yep :). This problem is an artifact of moving the timer_mod from
cpu_throttle_thread into cpu_throttle_timer_tick. I'll have to go back
to the review comments and look at why that was done.
--
-- Jason J. Herne (jjherne@linux.vnet.ibm.com)
next prev parent reply other threads:[~2015-07-31 17:42 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-02 16:36 [Qemu-devel] [PATCH v4 0/5] migration: Dynamic cpu throttling for auto-converge Jason J. Herne
2015-07-02 16:36 ` [Qemu-devel] [PATCH v4 1/5] cpu: Provide vcpu throttling interface Jason J. Herne
2015-07-02 16:43 ` Paolo Bonzini
2015-07-02 16:58 ` Dr. David Alan Gilbert
2015-07-13 14:43 ` Jason J. Herne
2015-07-13 15:14 ` Paolo Bonzini
2015-07-15 12:40 ` Jason J. Herne
2015-07-15 12:54 ` Paolo Bonzini
2015-07-16 14:21 ` Jason J. Herne
2015-07-23 9:59 ` Paolo Bonzini
2015-07-31 17:12 ` Jason J. Herne
2015-07-31 17:16 ` Paolo Bonzini
2015-07-31 17:42 ` Jason J. Herne [this message]
2015-07-31 18:11 ` Jason J. Herne
2015-08-01 9:40 ` Paolo Bonzini
2015-09-01 14:43 ` Jason J. Herne
2015-07-02 16:47 ` Andreas Färber
2015-07-02 16:36 ` [Qemu-devel] [PATCH v4 2/5] migration: Parameters for auto-converge cpu throttling Jason J. Herne
2015-07-02 16:36 ` [Qemu-devel] [PATCH v4 3/5] migration: Dynamic cpu throttling for auto-converge Jason J. Herne
2015-07-02 16:36 ` [Qemu-devel] [PATCH v4 4/5] qmp/hmp: Add throttle ratio to query-migrate and info migrate Jason J. Herne
2015-07-02 16:36 ` [Qemu-devel] [PATCH v4 5/5] migration: Disambiguate MAX_THROTTLE Jason J. Herne
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