Re: page fault.

Re: page fault.

[Rajagopal Ananthanarayanan]

"M.Jagadish Kumar" wrote:
> 
> hello,
> Is there any way in which i can know when the pagefault occured,
> i mean at what instruction of my program execution.
> Does OS provide any support. This would help me to improve my program.


Unless the test program is the only one on the system,
there are other programs which will affect the pagefault
of the test program,  since the pages of those other programs
affect the resident pages of the test program.

AFAICT, there is no direct means of saying which instructions
caused page faults ... things like /sbin/time can report
total page faults only.

Why are you specifically interested in page faults?

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Rajagopal Ananthanarayanan ("ananth")
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Re: ptes flags in compressed cache

[Stephen C. Tweedie]

Hi,

On Thu, Oct 26, 2000 at 01:52:45PM -0200, Rodrigo S. de Castro wrote:
> 
> 	I am working on a compressed cache for 2.2.16 and I am
> currently in a cache with no compression implementation. Well, at this
> step, I gotta a doubt of how can I mark the pages (actually, ptes)
> that are in my cache and neither present in memory nor in swap. This
> is essential when I have a page fault, and this page is not present in
> memory.

Reserve a SWP_ENTRY for compressed pages.  There's precedent for that:
SHM in 2.2 already uses that mechanism for swapped-out shared memory
pages.

--Stephen
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page fault.

[M.Jagadish Kumar]

hello,
Is there any way in which i can know when the pagefault occured,
i mean at what instruction of my program execution.
Does OS provide any support. This would help me to improve my program.
thanx
jagadish


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Re: page fault.

[afei]

On Fri, 27 Oct 2000, M.Jagadish Kumar wrote:

> hello,
> Is there any way in which i can know when the pagefault occured,
> i mean at what instruction of my program execution.
> Does OS provide any support. This would help me to improve my program.
> thanx
> jagadish
The way I use is to use oops message and System.map to locate the
subroutine where the oops occured. To find the exact line where the oops
occured, you need to either check assemble code or use more complicated
kernel debug technique. I think Rik covered some in his kernel debug
slides.

Fei

> 
> 
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Re: page fault.

[Rik van Riel]

On Thu, 26 Oct 2000 afei@jhu.edu wrote:
> On Fri, 27 Oct 2000, M.Jagadish Kumar wrote:
> 
> > Is there any way in which i can know when the pagefault occured,
> > i mean at what instruction of my program execution.
> > Does OS provide any support. This would help me to improve my program.

> The way I use is to use oops message and System.map to locate
> the subroutine where the oops occured. To find the exact line
> where the oops occured, you need to either check assemble code
> or use more complicated kernel debug technique. I think Rik
> covered some in his kernel debug slides.

You're confusing issues. A pagefault has NOTHING to do
with an oops...

Rik
--
"What you're running that piece of shit Gnome?!?!"
       -- Miguel de Icaza, UKUUG 2000

http://www.conectiva.com/		http://www.surriel.com/

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Re: page fault.

[afei]

You are right. I misunderstood what he wants. To know when the pagefault
occured, one simply can work on the pagefault handler. It is trivial.

Fei

On Thu, 26 Oct 2000, Rik van Riel wrote:

> On Thu, 26 Oct 2000 afei@jhu.edu wrote:
> > On Fri, 27 Oct 2000, M.Jagadish Kumar wrote:
> > 
> > > Is there any way in which i can know when the pagefault occured,
> > > i mean at what instruction of my program execution.
> > > Does OS provide any support. This would help me to improve my program.
> 
> > The way I use is to use oops message and System.map to locate
> > the subroutine where the oops occured. To find the exact line
> > where the oops occured, you need to either check assemble code
> > or use more complicated kernel debug technique. I think Rik
> > covered some in his kernel debug slides.
> 
> You're confusing issues. A pagefault has NOTHING to do
> with an oops...
> 
> Rik
> --
> "What you're running that piece of shit Gnome?!?!"
>        -- Miguel de Icaza, UKUUG 2000
> 
> http://www.conectiva.com/		http://www.surriel.com/
> 

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Re: page fault.

[Stephen C. Tweedie]

Hi,

On Thu, Oct 26, 2000 at 10:14:23PM -0400, afei@jhu.edu wrote:
> You are right. I misunderstood what he wants. To know when the pagefault
> occured, one simply can work on the pagefault handler. It is trivial.

Page faults already produce a SIGSEGV which gets passed a sigcontext
struct describing where the fault occurred.

--Stephen
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Re: page fault.

[Rajagopal Ananthanarayanan]

"Stephen C. Tweedie" wrote:
> 
> Hi,
> 
> On Thu, Oct 26, 2000 at 10:14:23PM -0400, afei@jhu.edu wrote:
> > You are right. I misunderstood what he wants. To know when the pagefault
> > occured, one simply can work on the pagefault handler. It is trivial.
> 
> Page faults already produce a SIGSEGV which gets passed a sigcontext
> struct describing where the fault occurred.
> 

Isn't it that only unsatisfied pagefaults generate
SIGSEGV? The original question was whether there
is a way to track all pagefaults in a given program.
Please correct if I'm wrong: the answer to this latter
question is no. Unless one modifies do_pagefault to
generate such a signal on all faults ...


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Rajagopal Ananthanarayanan ("ananth")
Member Technical Staff, SGI.
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Re: page fault.

[volodya]

I was interested in that too :)) So far the best I came up with was a
loadable module that prints out all pages in active memory. Perhaps you
can use it together with debugger to step through the program and see what
happens.

                          Vladimir Dergachev

On Fri, 27 Oct 2000, M.Jagadish Kumar wrote:

> hello,
> Is there any way in which i can know when the pagefault occured,
> i mean at what instruction of my program execution.
> Does OS provide any support. This would help me to improve my program.
> thanx
> jagadish
> 
> 
> --
> 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.eu.org/Linux-MM/
> 

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