[Crash-utility] [PATCH] Add -m option to kmem

[Zhang Yanfei]

于 2013年03月02日 05:20, Dave Anderson 写道:
> 
> 
> ----- Original Message -----
>> kmem -m is used for displaying information of all ksm pages or
>> some ksm pages for specified ksm stable tree node addresses
>> The information includes:
>>         - physical address of ksm page,
>>         - pid of tasks using this ksm page,
>>         - counts of ksm page references for each task
>>
>> for example:
>>     crash> kmem -m ffff8803573964c0
>>                  PID: 15864 16781
>>            793005000:  8713  5584
>>
>> ffff8803573964c0 is the address of ksm stable tree node.
>> task 15864 has 8713 virtual pages mapping the page with address 793005000.
>> task 16781 has 5584 virtual pages mapping the page with address 793005000.
>>
>> P.S.
>> This patch is based on the patch from Qiao(qiaonuohan at cn.fujitsu.com)
>>     0001-make-rbtree-manipulation-functions-global.patch
>> Because this patch also uses rb_tree operations.
> 
> I'll get to this patch after I get Qiao's patch straightened out and
> checked in.
> 
> But a couple quick questions... 
> 
> What does "kmem -m" alone look like?  Your help page example only
> shows the command passing a "ksm stable tree node address". 

'kmem -m' will display all the ksm pages.

 How
> would a user know what one of those addresses would be?

>From the structure "rmap_item" ? it has a member "head" that points
to a ksm stable tree node.

> 
> And for "kmem -m <address>", what if there are dozens of PIDs that
> are mapping the same physical address?  Regardless of the size of
> the display window, eventually it would get messy if it extends to 
> more than one line.  I try to avoid having commands extend beyond
> 80 columns if at all possible.  
> 

Hmm. If there are quite many PIDs, can the output be like below?

             PID: 15864 16781 16782 16783
       793005000:  8713  5584    23    23
                  12222 13333 14444 15555
                    232   232   334   456
                  ...

Thanks
Zhang