Question on conversion from MSIL to native code

[Dan]

Hi Gurus

I got a very basic question to ask:

When a .NET exe (MSIL) is first run, the JIT-compiler will converts the IL
into native codes so that it can executes on the current machine. my
question is:

1) where does the native codes reside? is it saved somewhere in the hard
drive or it will only resides in the memory? or does the JIT compiler writes
the native codes into the exe?

2) Is it persistent? meaining, the JIT compiler will only need to convert
once and the native code will remain in the system even after the system is
rebooted.

regards
dan

[Miha Markic]

Hi Dan,

"Dan" <bi*******@yahoo.com.sg> wrote in message
news:OS**************@TK2MSFTNGP09.phx.gbl...

Hi Gurus

I got a very basic question to ask:

When a .NET exe (MSIL) is first run, the JIT-compiler will converts the IL
into native codes so that it can executes on the current machine. my
question is:

1) where does the native codes reside? is it saved somewhere in the hard
drive or it will only resides in the memory? or does the JIT compiler writes the native codes into the exe?
Memory, not persisted.
2) Is it persistent? meaining, the JIT compiler will only need to convert
once and the native code will remain in the system even after the system is rebooted.

Nope, not persistent. You can use NGEN utility to created native images.

--
Miha Markic - RightHand .NET consulting & software development
miha at rthand com

[Dan]

Hi Miha

thanks for the reply. If it is not persisted and resides in the memory, is
it staying in the EXE process memory. What happens when the exe is
terminated? Does it means that the MSIL will always needs to be converted to
native code each time the .NET exe is executed? or does the conversion only
happens once when the exe is first run?

thanks
dan
"Miha Markic" <miha at rthand com> wrote in message
news:Oo**************@TK2MSFTNGP12.phx.gbl...

Hi Dan,

"Dan" <bi*******@yahoo.com.sg> wrote in message
news:OS**************@TK2MSFTNGP09.phx.gbl...

Hi Gurus

I got a very basic question to ask:

When a .NET exe (MSIL) is first run, the JIT-compiler will converts the IL into native codes so that it can executes on the current machine. my
question is:

1) where does the native codes reside? is it saved somewhere in the hard
drive or it will only resides in the memory? or does the JIT compiler

writes

the native codes into the exe?

Memory, not persisted.

2) Is it persistent? meaining, the JIT compiler will only need to convert once and the native code will remain in the system even after the system

is

rebooted.

Nope, not persistent. You can use NGEN utility to created native images.

--
Miha Markic - RightHand .NET consulting & software development
miha at rthand com

[Miha Markic]

Hi Dan,

"Dan" <bi*******@yahoo.com.sg> wrote in message
news:OV****************@TK2MSFTNGP12.phx.gbl...

Hi Miha

thanks for the reply. If it is not persisted and resides in the memory, is
it staying in the EXE process memory. What happens when the exe is
terminated? Does it means that the MSIL will always needs to be converted to native code each time the .NET exe is executed?
Yup.

or does the conversion only happens once when the exe is first run?

No. It happens always unless you NGEN-it.

--
Miha Markic - DXSquad/RightHand .NET consulting & software development
miha at rthand com

[Dan]

Hi Miha

first of all thanks for your time.

but I can clearly see a difference between the first and subsequent time
run. The subsequent executions are clearly faster than the first. I'm really
curious on what makes up the differences. I'm running it on XP Pro.

Also, I'm hesitated to use NGEN because I heard somewhere that it will
actually produced native codes for you that are very much optimized for the
machine you NGENed, so you may have performance isssues when running another
machine. Furthermore, I not sure if there is any compatibility issue, say if
I NGENed it on XP Pro(using Intel CPU), will the generated native code be
able to run on another XP Pro running on AMD CPU?

can you recomend some websites or online resources at MS for further
information? on this matter as well as for NGEN? thank you very much.

thanks
dan
"Miha Markic" <miha at rthand com> wrote in message
news:ul**************@TK2MSFTNGP12.phx.gbl...

Hi Dan,

"Dan" <bi*******@yahoo.com.sg> wrote in message
news:OV****************@TK2MSFTNGP12.phx.gbl...

Hi Miha

thanks for the reply. If it is not persisted and resides in the memory, is it staying in the EXE process memory. What happens when the exe is
terminated? Does it means that the MSIL will always needs to be

converted to

native code each time the .NET exe is executed?

Yup.

or does the conversion only

happens once when the exe is first run?

No. It happens always unless you NGEN-it.

--
Miha Markic - DXSquad/RightHand .NET consulting & software development
miha at rthand com

[Miha Markic]

Hi Dan,

"Dan" <bi*******@yahoo.com.sg> wrote in message
news:eR**************@TK2MSFTNGP12.phx.gbl...

Hi Miha

first of all thanks for your time.

but I can clearly see a difference between the first and subsequent time
run. The subsequent executions are clearly faster than the first. I'm really curious on what makes up the differences. I'm running it on XP Pro.
Maybe because assemblies are already in memory (.net didn't relase them yet)
or in cache or something.
But, they are in memory.
Also, I'm hesitated to use NGEN because I heard somewhere that it will
actually produced native codes for you that are very much optimized for the machine you NGENed, so you may have performance isssues when running another machine.Furthermore, I not sure if there is any compatibility issue, say if I NGENed it on XP Pro(using Intel CPU), will the generated native code be
able to run on another XP Pro running on AMD CPU?
Right. That's why you have to ngen them on the machine itself.
Plus, the ngenized code runs a bit slower than code that is JITed.
can you recomend some websites or online resources at MS for further
information? on this matter as well as for NGEN? thank you very much.

http://msdn.microsoft.com/library/de...etperftips.asp

http://msdn.microsoft.com/library/de...torNgenexe.asp

http://msdn.microsoft.com/library/de...tperftechs.asp

--
Miha Markic - DXSquad/RightHand .NET consulting & software development
miha at rthand com