[CRIU] p.haul page statistics

[Pavel Emelyanov]

On 09/13/2016 08:18 PM, Adrian Reber wrote:
> On Tue, Sep 13, 2016 at 06:12:28PM +0300, Pavel Emelyanov wrote:
>> On 09/12/2016 03:08 PM, Mike Rapoport wrote:
>>> On Mon, Sep 12, 2016 at 11:02:34AM +0200, Adrian Reber wrote:
>>>> On Thu, Sep 08, 2016 at 08:39:06AM +0300, Mike Rapoport wrote:
>>>>> On Tue, Sep 06, 2016 at 11:35:23AM +0200, Adrian Reber wrote:
>>>>>> Using the latest criu with p.haul the information about the pages dumped
>>>>>> looks a bit wrong. From p.haul I get:
>>>
>>> [ snip ]
>>>  
>>>>>> So p.haul is kind of right as the stats file says that only 13 pages
>>>>>> have been written. But all the lazy pages have also been written.
>>>>>>
>>>>>> Should pages_written include the lazy pages or should p.haul add
>>>>>> pages_written and pages_lazy to get the actual number of pages written?
>>>>>
>>>>> I think p.haul should add pages_written and pages_lazy.
>>>>
>>>> I thought some more about this and I am not convinced. 'pages_written'
>>>> sounds like all pages written. Unrelated if the pages are lazy or not.
>>>  
>>> Agree. How about the patch below?
>>>
>>>> Are there any advantages I do not see if the lazy pages are not included
>>>> in 'pages_written'? In the future when p.haul might know how to combine
>>>> pre-copy and post-copy the variable 'pages_lazy' will become important
>>>> but right now it feels wrong to read it to decide if additional pre-copy
>>>> runs should be performed.
>>>>
>>>> 		Adrian
>>>>
>>>
>>> >From 898ab269a6b4a47ed8019445b688dfd3d41d0581 Mon Sep 17 00:00:00 2001
>>> From: Mike Rapoport <rppt at linux.vnet.ibm.com>
>>> Date: Mon, 12 Sep 2016 15:05:13 +0300
>>> Subject: [CRIU][PATCH] criu: mem: count all pages actually written to image as
>>>  "pages_written"
>>>
>>> When potentially lazy pages are written to image add their count to
>>> "pages_written" stats counter.
>>
>> Erm... I saw Adrian's thoughts on counting lazy pages as written, but now I
>> disagree with that. If we treat pages_written as "pages that went into the
>> image file", then this definition is clean and understandable. But how to
>> define pages_written if we count lazy pages there as well?
>>
>> Can we better leave pages_written as "pages that are in the images" and, if
>> we need it, introduce pages_dumped to count all the pages that are to be
>> taken with us regardless whether they are in the image or lazy?
> 
> The problem I see is with p.haul during the pre-dump. Maybe pages should
> not be counted as lazy in the pre-dump case. There is no use to count
> lazy pages during pre-dump.

Agreed. On pre-dump lazy pages do not make sense. But AFAIU they are not
counted.

Mike?

> 		Adrian
> .
>