[parisc-linux] struct page: page in use or not ?

[parisc-linux] struct page: page in use or not ?

[bruno_vidal]

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    Hi
I'm currently trying to reduce the dump time, and then I try to dump only
pages that are currently use by the system. In page structure I found a flag,
I was thinking a good one for this purpose:
atomic_t count;                 /* Usage count, see below. */

But after taking only pages where count != 0, something was broken, I was
not able to look at proc structure, and several things.....
If a do a "full" dump I'm still able to look at what I need, so this page.count
is not accurate for this purpose. So does't exist a good way to know if a page
is in use or not ?

    thanks.


--
        Vidal Bruno, (770-4271)
        SSD-HA Team, HP-UX & LINUX Support
        bruno_vidal@admin.france.hp.com



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Re: [parisc-linux] struct page: page in use or not ?

[Randolph Chung]

> I'm currently trying to reduce the dump time, and then I try to dump only
> pages that are currently use by the system. In page structure I found a flag,
> I was thinking a good one for this purpose:
> atomic_t count;                 /* Usage count, see below. */

Bruno, isn't this handled in the generic dump code? I haven't looked at
this for a while, but I thought the generic dump code lets you configure
whether to dump all kernel pages, all kernel+user referened pages or
all pages whether referenced or not...

randolph
-- 
Randolph Chung
Debian GNU/Linux Developer, hppa/ia64 ports
http://www.tausq.org/

Re: [parisc-linux] struct page: page in use or not ?

[Matthew Wilcox]

On Wed, Mar 19, 2003 at 05:50:46PM +0100, bruno_vidal@hp.com wrote:
>     Hi
> I'm currently trying to reduce the dump time, and then I try to dump only
> pages that are currently use by the system. In page structure I found a flag,
> I was thinking a good one for this purpose:
> atomic_t count;                 /* Usage count, see below. */
> 
> But after taking only pages where count != 0, something was broken, I was
> not able to look at proc structure, and several things.....
> If a do a "full" dump I'm still able to look at what I need, so this page.count
> is not accurate for this purpose. So does't exist a good way to know if a page
> is in use or not ?

The problem is multi-page allocs.  The `struct page' is not valid
for those.  I'm not sure what a good way of doing this is -- have you
looked at the swsusp patches to see how they do it?

-- 
"It's not Hollywood.  War is real, war is primarily not about defeat or
victory, it is about death.  I've seen thousands and thousands of dead bodies.
Do you think I want to have an academic debate on this subject?" -- Robert Fisk

Re: [parisc-linux] struct page: page in use or not ?

[bruno_vidal]

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    Hi
What do you mean by "swsusp" patche ? What it do....
Actually I'm looking at the kmalloc() function in order to
understand how it determine the bucket, and so to know
which pages I need to dump before I can use the page structure.
Do you think it is a good starting point, or using page
struture is really a bad option ?

    Thanks.

Matthew Wilcox wrote:

> On Wed, Mar 19, 2003 at 05:50:46PM +0100, bruno_vidal@hp.com wrote:
> >     Hi
> > I'm currently trying to reduce the dump time, and then I try to dump only
> > pages that are currently use by the system. In page structure I found a flag,
> > I was thinking a good one for this purpose:
> > atomic_t count;                 /* Usage count, see below. */
> >
> > But after taking only pages where count != 0, something was broken, I was
> > not able to look at proc structure, and several things.....
> > If a do a "full" dump I'm still able to look at what I need, so this page.count
> > is not accurate for this purpose. So does't exist a good way to know if a page
> > is in use or not ?
>
> The problem is multi-page allocs.  The `struct page' is not valid
> for those.  I'm not sure what a good way of doing this is -- have you
> looked at the swsusp patches to see how they do it?
>
> --
> "It's not Hollywood.  War is real, war is primarily not about defeat or
> victory, it is about death.  I've seen thousands and thousands of dead bodies.
> Do you think I want to have an academic debate on this subject?" -- Robert Fisk
> _______________________________________________
> parisc-linux mailing list
> parisc-linux@lists.parisc-linux.org
> http://lists.parisc-linux.org/mailman/listinfo/parisc-linux

--
        Vidal Bruno, (770-4271)
        SSD-HA Team, HP-UX & LINUX Support
        bruno_vidal@admin.france.hp.com



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Re: [parisc-linux] struct page: page in use or not ?

[Matthew Wilcox]

On Thu, Mar 20, 2003 at 12:23:08PM +0100, bruno_vidal@hp.com wrote:
>     Hi
> What do you mean by "swsusp" patche ? What it do....
> Actually I'm looking at the kmalloc() function in order to
> understand how it determine the bucket, and so to know
> which pages I need to dump before I can use the page structure.
> Do you think it is a good starting point, or using page
> struture is really a bad option ?

kmalloc (ie slab) is the wrong allocator to be looking at.  you want
get_free_pages.

-- 
"It's not Hollywood.  War is real, war is primarily not about defeat or
victory, it is about death.  I've seen thousands and thousands of dead bodies.
Do you think I want to have an academic debate on this subject?" -- Robert Fisk

Re: [parisc-linux] struct page: page in use or not ?

[Michael Wood]

On Thu, Mar 20, 2003 at 12:23:08PM +0100, bruno_vidal@hp.com wrote:
>     Hi
> What do you mean by "swsusp" patche ? What it do....

swsusp = Software Suspend

http://fchabaud.free.fr/English/default.php3?COUNT=3&FILE0=Tricks&FILE1=Laptop&FILE2=Swsusp

	Software suspend is a kernel patch that provides the ability to
	suspend execution of the kernel without using any APM BIOS
	feature. This is really useful either if your BIOS is broken
	(for instance you have bought a larger disk than the original
	one and the BIOS is unable to handle it :-() or if you
	frequently swap from windows to linux because this feature
	allows you to save your linux session on disk instead of
	rebooting.

-- 
Michael Wood <mwood@its.uct.ac.za>