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Re: [Qemu-devel] [RFC PATCH v4 17/25] cpus: make icount warp determinist
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [RFC PATCH v4 17/25] cpus: make icount warp deterministic in replay mode |
Date: |
Fri, 07 Nov 2014 13:00:55 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 |
On 07/11/2014 12:45, Pavel Dovgaluk wrote:
>> From: Paolo Bonzini [mailto:address@hidden
>> On 07/11/2014 11:33, Pavel Dovgalyuk wrote:
>>> This patch adds saving and replaying warping parameters in record and replay
>>> modes. These parameters affect on virtual clock values and therefore should
>>> be deterministic.
>>
>> Why are QEMU_CLOCK_REALTIME timers not recorded/replayed like
>> QEMU_CLOCK_HOST is?
>
> We cannot record all QEMU_CLOCK_REALTIME timers, because they are
> simulator-related timers,
> not the VM-related ones. If we'll record them then we'll have to replay
> simulator
> execution. And we want just to replay VM allowing different realtime events
> to be
> non-replayable (like screen refresh, monitor events handling, and so on).
Hmm... I think you want the icount_rt timer to use what
QEMU_CLOCK_VIRTUAL does in !use_icount mode. Maybe you can add a fourth
clock, QEMU_CLOCK_VIRTUAL_RT and use this one independent of the replay
mode. This clock can then be traced like QEMU_CLOCK_HOST.
The problem is that QEMU_CLOCK_HOST can move backwards or forwards,
sometimes by as much as 1 hour, so it's not the best match for this case.
Paolo
- Re: [Qemu-devel] [RFC PATCH v4 11/25] cpu-exec: allow temporary disabling icount, (continued)
- [Qemu-devel] [RFC PATCH v4 12/25] replay: interrupts and exceptions, Pavel Dovgalyuk, 2014/11/07
- [Qemu-devel] [RFC PATCH v4 13/25] replay: asynchronous events infrastructure, Pavel Dovgalyuk, 2014/11/07
- [Qemu-devel] [RFC PATCH v4 14/25] cpu: replay instructions sequence, Pavel Dovgalyuk, 2014/11/07
- [Qemu-devel] [RFC PATCH v4 15/25] replay: recording and replaying clock ticks, Pavel Dovgalyuk, 2014/11/07
- [Qemu-devel] [RFC PATCH v4 17/25] cpus: make icount warp deterministic in replay mode, Pavel Dovgalyuk, 2014/11/07
- [Qemu-devel] [RFC PATCH v4 16/25] replay: recording and replaying different timers, Pavel Dovgalyuk, 2014/11/07
- [Qemu-devel] [RFC PATCH v4 18/25] replay: shutdown event, Pavel Dovgalyuk, 2014/11/07
- [Qemu-devel] [RFC PATCH v4 19/25] replay: checkpoints, Pavel Dovgalyuk, 2014/11/07
- [Qemu-devel] [RFC PATCH v4 20/25] replay: bottom halves, Pavel Dovgalyuk, 2014/11/07
- [Qemu-devel] [RFC PATCH v4 21/25] replay: replay aio requests, Pavel Dovgalyuk, 2014/11/07
- [Qemu-devel] [RFC PATCH v4 22/25] replay: thread pool, Pavel Dovgalyuk, 2014/11/07
- [Qemu-devel] [RFC PATCH v4 23/25] replay: initialization and deinitialization, Pavel Dovgalyuk, 2014/11/07
- [Qemu-devel] [RFC PATCH v4 24/25] replay: command line options, Pavel Dovgalyuk, 2014/11/07
- [Qemu-devel] [RFC PATCH v4 25/25] replay: recording of the user input, Pavel Dovgalyuk, 2014/11/07