Non deterministic routing in Quartus 3.0 ?

G

g. giachella

Guest
I have launched the place & route of the same project on two different
machines, a PC 2.6 GHz (WIN 2000) and a COMPAQ XEON 700 MHz
Workstation (WIN NT 4). Same project means same .vhd, .edf, .csf,
..psf, .ssf, .esf, .quartus files.
The QUARTUS release is the same (same build, same SP).
I obtained two different placements and two different compile times
(PC = 1h 40 min, Workstation = 5h 22 min): the file ..fit.rpt
evidences that the options "Use Local Routing Input" and "Use Local
Routing Output" were set differently between them during the
compilation.
As the project are the same and the seed is also the same, I would
expect identical place and route.

Any comment ? Am I missing somenthing ?

Thanks in advance
 
g. giachella wrote:
I have launched the place & route of the same project on two different
machines, a PC 2.6 GHz (WIN 2000) and a COMPAQ XEON 700 MHz
Workstation (WIN NT 4). Same project means same .vhd, .edf, .csf,
.psf, .ssf, .esf, .quartus files.
The QUARTUS release is the same (same build, same SP).
I obtained two different placements and two different compile times
(PC = 1h 40 min, Workstation = 5h 22 min): the file ..fit.rpt
evidences that the options "Use Local Routing Input" and "Use Local
Routing Output" were set differently between them during the
compilation.
As the project are the same and the seed is also the same, I would
expect identical place and route.

Any comment ? Am I missing somenthing ?
Click to expand...
Your win2k box is faster than your nt box.

Lets assume that place & route is mostly compute bound.
In that case, if I didn't know the answer, I would
estimate the NT test time as:

(100 min) (2.6/.7) = 371 min = 6 hours


So you are doing better than I would expect.


-- Mike Treseler
 
Mike Treseler <mike.treseler@flukenetworks.com> wrote in message news:<400D7312.1090304@flukenetworks.com>...
g. giachella wrote:
I have launched the place & route of the same project on two different
machines, a PC 2.6 GHz (WIN 2000) and a COMPAQ XEON 700 MHz
Workstation (WIN NT 4). Same project means same .vhd, .edf, .csf,
.psf, .ssf, .esf, .quartus files.
The QUARTUS release is the same (same build, same SP).
I obtained two different placements and two different compile times
(PC = 1h 40 min, Workstation = 5h 22 min): the file ..fit.rpt
evidences that the options "Use Local Routing Input" and "Use Local
Routing Output" were set differently between them during the
compilation.
As the project are the same and the seed is also the same, I would
expect identical place and route.

Any comment ? Am I missing somenthing ?

Your win2k box is faster than your nt box.

Lets assume that place & route is mostly compute bound.
In that case, if I didn't know the answer, I would
estimate the NT test time as:

(100 min) (2.6/.7) = 371 min = 6 hours


So you are doing better than I would expect.


-- Mike Treseler
Click to expand...

The different compile time is just CPU speed differences, as Mike
explained. For the different placement and routing, I can only think
of two things:

1. You changed some option without realizing it between the two
compiles. Are "Use Local Routing Input" and "Use Local Routing
Output" options you set for the compiler, and you're saying they have
different values in the two fit.rpt files? If so, that indicates you
have unintentionally changed a setting between the two compiles, which
would explain the different place and route.

2. We have occasionally gotten different fits on different versions of
Windows due to things like qsort breaking ties differently in
different windows versions. A slight difference at one point in the
compile leads to a different fit on the two platforms. Both are valid
fits; they are just different. As we find these cases, we get rid of
them by doing things like writing our own qsort that breaks ties in a
deterministic way.

So it's rare, but we do find these cases.

Regards,

Vaughn
Altera
 
Mike Treseler <mike.treseler@flukenetworks.com> wrote in message news:<400D7312.1090304@flukenetworks.com>...
g. giachella wrote:
I have launched the place & route of the same project on two different
machines, a PC 2.6 GHz (WIN 2000) and a COMPAQ XEON 700 MHz
Workstation (WIN NT 4). Same project means same .vhd, .edf, .csf,
.psf, .ssf, .esf, .quartus files.
The QUARTUS release is the same (same build, same SP).
I obtained two different placements and two different compile times
(PC = 1h 40 min, Workstation = 5h 22 min): the file ..fit.rpt
evidences that the options "Use Local Routing Input" and "Use Local
Routing Output" were set differently between them during the
compilation.
As the project are the same and the seed is also the same, I would
expect identical place and route.

Any comment ? Am I missing somenthing ?

Your win2k box is faster than your nt box.

Lets assume that place & route is mostly compute bound.
In that case, if I didn't know the answer, I would
estimate the NT test time as:

(100 min) (2.6/.7) = 371 min = 6 hours


So you are doing better than I would expect.


-- Mike Treseler
Click to expand...
I agree with you, but my real question is: why, if the two projects
starting point is the same, the two placements obtained are different,
when compared ? Is Quartus p&r algorithm non deterministic ?
 
vbetz@altera.com (Vaughn Betz) wrote in message news:<48761f7f.0401202037.79907801@posting.google.com>...
Mike Treseler <mike.treseler@flukenetworks.com> wrote in message news:<400D7312.1090304@flukenetworks.com>...
g. giachella wrote:
I have launched the place & route of the same project on two different
machines, a PC 2.6 GHz (WIN 2000) and a COMPAQ XEON 700 MHz
Workstation (WIN NT 4). Same project means same .vhd, .edf, .csf,
.psf, .ssf, .esf, .quartus files.
The QUARTUS release is the same (same build, same SP).
I obtained two different placements and two different compile times
(PC = 1h 40 min, Workstation = 5h 22 min): the file ..fit.rpt
evidences that the options "Use Local Routing Input" and "Use Local
Routing Output" were set differently between them during the
compilation.
As the project are the same and the seed is also the same, I would
expect identical place and route.

Any comment ? Am I missing somenthing ?

Your win2k box is faster than your nt box.

Lets assume that place & route is mostly compute bound.
In that case, if I didn't know the answer, I would
estimate the NT test time as:

(100 min) (2.6/.7) = 371 min = 6 hours


So you are doing better than I would expect.


-- Mike Treseler


The different compile time is just CPU speed differences, as Mike
explained. For the different placement and routing, I can only think
of two things:

1. You changed some option without realizing it between the two
compiles. Are "Use Local Routing Input" and "Use Local Routing
Output" options you set for the compiler, and you're saying they have
different values in the two fit.rpt files? If so, that indicates you
have unintentionally changed a setting between the two compiles, which
would explain the different place and route.

2. We have occasionally gotten different fits on different versions of
Windows due to things like qsort breaking ties differently in
different windows versions. A slight difference at one point in the
compile leads to a different fit on the two platforms. Both are valid
fits; they are just different. As we find these cases, we get rid of
them by doing things like writing our own qsort that breaks ties in a
deterministic way.

So it's rare, but we do find these cases.

Regards,

Vaughn
Altera
Click to expand...
Thank you for your interest.
I have launched a new compilation on a pc only and, again, the result
is different from the previous launched on the same pc. I don't
understand why ...
 
giachella.g@laben.it (g. giachella) writes:

I have launched a new compilation on a pc only and, again, the result
is different from the previous launched on the same pc. I don't
understand why ...
Click to expand...
Do you have smart compilation enabled? If yes, then it will use the
result of the previous iteration as the base for the next.

Make a backup. Then delete all but your source files and start in a
fresh directory.

Petter

--
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet and in e-mail?
 
Petter Gustad <newsmailcomp6@gustad.com> wrote in message news:<8765f37trt.fsf@zener.home.gustad.com>...
giachella.g@laben.it (g. giachella) writes:

I have launched a new compilation on a pc only and, again, the result
is different from the previous launched on the same pc. I don't
understand why ...

Do you have smart compilation enabled? If yes, then it will use the
result of the previous iteration as the base for the next.

Make a backup. Then delete all but your source files and start in a
fresh directory.

Petter
Click to expand...
In my tests, every time I start a new p&r, I put the project files
(.edf, .vhd, .quartus, .psf, .csf, .ssf, .esf) in a new empty
directory, so that the new compilation can't be based on previous
compilations.
Furthermore "normal" compilation is enabled.

Giuseppe
 
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