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

[Dave Anderson]

----- Original Message -----
> 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.

I meant could you show an example of "kmem -m"...

> 
> > 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.

So does "kmem -m" show a list of those addresses?

> > 
> > 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
>                   ...

Well, that's not much clearer -- it's difficult to tell whether the
numbers are PIDs or counts.

Dave