[PATCH] initial detailed VM statistics code

[PATCH] initial detailed VM statistics code

[Marcelo Tosatti]

Hi, 

Well, I've started working on VM stats code for 2.4. 

vmstat output: 

# r  b  w   swpd   free   buff  cache   si   so    bi    bo   in    cs us sy id
# 0  1  1 102624   1412    120  89472   90 9114   304  9160  336  1102  12 7 92

This is the already known part..

# launder launder_w ref_inact alloc_r kswapd_w krec_w kflush_w
#     33       11       147    1260       23    328      151

First, the global statistics:

launder: nr of page_launder() calls
launder_w: nr of times page_launder() started writing out pages
ref_inac: nr of refill_inactive_scan() calls
alloc_r: number of reschedules on __alloc_pages()
kswapd_w: kswapd wakeups
krec_w: kreclaimd wakeups
kflush_w: kflushd wakeups

# Zone fshort ishort   scan  clean  skipl  skipd launder  react rescue deact recfail
#    DMA      0    224   3915   1500    342   1406    531    153      0 452 636
# Normal      0      0  28073  12490   2451   9295   2678    676      0 2654     947

Then the perzone statistics:

fshort: per-zone free shortage
ishort: per-zone inactive shortage
scan: number of pages scanned by page_launder
clean: number of pages cleaned by page_launder
skipl: number of locked pages skipped by page_launder
skipd: number of unlocked but dirty pages skipped by page_launder
launder: number of pages laundered by page_launder
react: number of pages reactivated by page_launder
rescue: number of pages reactivated by reclaim_page
deat: number of pages deactivated by refill_inactive_scan
recfail: number of reclaim_page failures


The code: 

Patch against 2.4.6pre9:
http://bazar.conectiva.com.br/~marcelo/patches/v2.4/2.4.6pre9/vmstats.patch

Patch against procps from Conectiva's srpm (which is not stock procps):
http://bazar.conectiva.com.br/~marcelo/patches/v2.4/2.4.6pre9/procps.patch

And full vmstat.c so people don't need to get Conectiva's srpm:
http://bazar.conectiva.com.br/~marcelo/patches/v2.4/2.4.6pre9/vmstat.c

The vmstat code is really crappy and new fields are painfull to add. If
anyone is willing to help me to write a decent vmstat, tell me. 

The hacked vmstat will coredump on a non-patched kernel.


--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/

Re: [PATCH] initial detailed VM statistics code

[Marcelo Tosatti]

On Wed, 4 Jul 2001, Joseph A. Knapka wrote:

> Marcelo Tosatti wrote:
> > 
> > Hi,
> > 
> > Well, I've started working on VM stats code for 2.4.
> > 
> 
> Thanks.
> 
> It might be useful to have a count of the number of PTEs scanned
> by swap_out(), and the number of those that were unmapped. (I'm
> interested in the scan rate of swap_out() vs refill_inactive_scan()).

Hum, 

The number of pages with age 0 which have mapped PTEs (thus cannot be
freed) is what you're looking for ?

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/

Re: [PATCH] initial detailed VM statistics code

[Joseph A. Knapka]

Marcelo Tosatti wrote:
> 
> Hi,
> 
> Well, I've started working on VM stats code for 2.4.
> 

Thanks.

It might be useful to have a count of the number of PTEs scanned
by swap_out(), and the number of those that were unmapped. (I'm
interested in the scan rate of swap_out() vs refill_inactive_scan()).

I have a module that produces a histogram of pages-vs-age and
pages-vs-references for pages on the active_list, as well as
some other general VM stats; the code is available here:

<URL: http://home.earthlink.net/~jknapka/linux-mm/vmstatd1.c>

I'm not sure how generally useful it is, but you can make some
pretty pictures with it :-)

-- Joe Knapka
"You know how many remote castles there are along the gorges? You
 can't MOVE for remote castles!" -- Lu Tze re. Uberwald
// Linux MM Documentation in progress:
// http://home.earthlink.net/~jknapka/linux-mm/vmoutline.html
* Evolution is an "unproven theory" in the same sense that gravity is. *
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/

Re: [PATCH] initial detailed VM statistics code

[Joseph A. Knapka]

Marcelo Tosatti wrote:
> 
> On Wed, 4 Jul 2001, Joseph A. Knapka wrote:
> 
> > Marcelo Tosatti wrote:
> > >
> > > Hi,
> > >
> > > Well, I've started working on VM stats code for 2.4.
> > >
> >
> > Thanks.
> >
> > It might be useful to have a count of the number of PTEs scanned
> > by swap_out(), and the number of those that were unmapped. (I'm
> > interested in the scan rate of swap_out() vs refill_inactive_scan()).
> 
> Hum,
> 
> The number of pages with age 0 which have mapped PTEs (thus cannot be
> freed) is what you're looking for ?

Well, I'm just not sure :-)  I'm looking for anything practical that
would give insight into the VM system. Maybe if I looked at PTE
scan rates and page frame scan rates for a while I'd conclude that
in fact, age-zero-but-unfreeable-page-count is a critical number (it
seems like it would be). But maybe I'd conclude something else.

I guess from a purely pedagogical standpoint, I'm interested in
knowing the general shape of the mapping from VM onto physical
memory at a given time - how much total virtual space is being
mapped into RAM, and how it's shared, and whether VM is
scanned at approximately the same relative rate as physical
RAM. That information may be utterly useless from a VM
tuning standpoint, I don't know.

It would, IMO, be nice to have as much VM state as possible
exported for use by modules (if requested by the user at
configuration time), so that we can gather whatever statistics
we want without patching the kernel a lot.

Thanks,

-- Joe Knapka
"You know how many remote castles there are along the gorges? You
 can't MOVE for remote castles!" -- Lu Tze re. Uberwald
// Linux MM Documentation in progress:
// http://home.earthlink.net/~jknapka/linux-mm/vmoutline.html
* Evolution is an "unproven theory" in the same sense that gravity is. *
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/

Re: [PATCH] initial detailed VM statistics code

[Marcelo Tosatti]

On Wed, 4 Jul 2001, Joseph A. Knapka wrote:

> Marcelo Tosatti wrote:
> > 
> > On Wed, 4 Jul 2001, Joseph A. Knapka wrote:
> > 
> > > Marcelo Tosatti wrote:
> > > >
> > > > Hi,
> > > >
> > > > Well, I've started working on VM stats code for 2.4.
> > > >
> > >
> > > Thanks.
> > >
> > > It might be useful to have a count of the number of PTEs scanned
> > > by swap_out(), and the number of those that were unmapped. (I'm
> > > interested in the scan rate of swap_out() vs refill_inactive_scan()).
> > 
> > Hum,
> > 
> > The number of pages with age 0 which have mapped PTEs (thus cannot be
> > freed) is what you're looking for ?
> 
> Well, I'm just not sure :-)  I'm looking for anything practical that
> would give insight into the VM system. Maybe if I looked at PTE
> scan rates and page frame scan rates for a while I'd conclude that
> in fact, age-zero-but-unfreeable-page-count is a critical number (it
> seems like it would be). But maybe I'd conclude something else.
> 
> I guess from a purely pedagogical standpoint, I'm interested in
> knowing the general shape of the mapping from VM onto physical
> memory at a given time - how much total virtual space is being
> mapped into RAM, and how it's shared, and whether VM is
> scanned at approximately the same relative rate as physical
> RAM. That information may be utterly useless from a VM
> tuning standpoint, I don't know.
> 
> It would, IMO, be nice to have as much VM state as possible
> exported for use by modules (if requested by the user at
> configuration time), so that we can gather whatever statistics
> we want without patching the kernel a lot.

Well, I'll add the nr of scanned/deactivated pte's anyway.

The information is needed. 

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/