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git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@7299 f3b2605a-c512-4ea7-a41b-209d697bcdaa

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62
doc/processors.html
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@ -13,15 +13,27 @@
</H3>
<P><B>Syntax:</B>
</P>
<PRE>processors Px Py Pz
<PRE>processors Px Py Pz keyword args ...
</PRE>
<UL><LI>Px,Py,Pz = # of processors in each dimension of a 3d grid
<LI>zero or more keyword/arg pairs may be appended
<LI>keyword = <I>part</I>
<PRE> <I>part</I> args = Psend Precv cstyle
Psend = partition # (1 to Np) which will send its processor layout
Precv = partition # (1 to Np) which will recv the processor layout
cstyle = <I>multiple</I>
<I>multiple</I> = Psend layout will be multiple of Precv layout in each dimension
</PRE>
</UL>
<P><B>Examples:</B>
</P>
<PRE>processors 2 4 4
processors * * 5
processors * 1 10
processors * * * part 1 2 multiple
</PRE>
<P><B>Description:</B>
</P>
@ -52,6 +64,52 @@ section</A> for an explanation of the
grid such as 1 x P x 1 will be required, which may incur extra
communication costs.
</P>
<HR>
<P>The <I>part</I> keyword can be useful when running in multi-partition mode,
e.g. with the <A HREF = "run_style.html<A HREF = "Section_start.html#start_6">-partition">>run_style verlet/split</A> command. It
specifies a dependency bewteen a sending partition <I>Psend</I> and a
receiving partition <I>Precv</I> which is enforced when each is setting up
their own mapping of the partitions processors to the simulation box.
Each of <I>Psend</I> and <I>Precv</I> must be integers from 1 to Np, where Np is
the number of partitions you have defined via the <A HREF = </A>
command-line switch</A>.
</P>
<P>A "dependency" means that the sending partition will create its 3d
logical grid as Px by Py by Pz and after it has done this, it will
send the Px,Py,Pz values to the receiving partition. The receiving
partition will wait to receive these values before creating its own 3d
logical grid and will use the sender's Px,Py,Pz values as a
constraint. The nature of the constraint is determined by the
<I>cstyle</I> argument.
</P>
<P>For a <I>cstyle</I> of <I>multiple</I>, each dimension of the sender's processor
grid is required to be an integer multiple of the corresponding
dimension in the receiver's processor grid. This is a requirement of
the <A HREF = "run_style.html">run_style verlet/split</A> command.
</P>
<P>For example, assume the sending partition creates a 4x6x10 grid = 240
processor grid. If the receiving partition is running on 80
processors, it could create a 4x2x10 grid, but it will not create a
2x4x10 grid, since in the y-dimension, 6 is not an integer multiple of
4.
</P>
<HR>
<P>Note that you can use the <A HREF = "partition.html">partition</A> command to
specify different processor grids for different partitions, e.g.
</P>
<PRE>partition yes 1 processors 4 4 4
partition yes 2 processors 2 3 2
</PRE>
<P>IMPORTANT NOTE: If you use the <A HREF = "partition.html">partition</A> command to
invoke different "processsors" commands on different partitions, and
you also use the <I>part</I> keyword, then you must insure that both the
sending and receiving partitions invoke the "processors" command that
connects the 2 partitions via the <I>part</I> keyword. LAMMPS cannot
easily check for this, but your simulation will likely hang in its
setup phase if this error has been made.
</P>
<P><B>Restrictions:</B>
</P>
<P>This command cannot be used after the simulation box is defined by a

60
doc/processors.txt
View File

@ -10,15 +10,23 @@ processors command :h3
[Syntax:]
processors Px Py Pz :pre
processors Px Py Pz keyword args ... :pre
Px,Py,Pz = # of processors in each dimension of a 3d grid :ul
Px,Py,Pz = # of processors in each dimension of a 3d grid :ulb,l
zero or more keyword/arg pairs may be appended :l
keyword = {part} :l
{part} args = Psend Precv cstyle
Psend = partition # (1 to Np) which will send its processor layout
Precv = partition # (1 to Np) which will recv the processor layout
cstyle = {multiple}
{multiple} = Psend layout will be multiple of Precv layout in each dimension :pre
:ule
[Examples:]
processors 2 4 4
processors * * 5
processors * 1 10 :pre
processors * * * part 1 2 multiple :pre
[Description:]
@ -49,6 +57,52 @@ Note that if you run on a large, prime number of processors P, then a
grid such as 1 x P x 1 will be required, which may incur extra
communication costs.
:line
The {part} keyword can be useful when running in multi-partition mode,
e.g. with the "run_style verlet/split"_run_style.html command. It
specifies a dependency bewteen a sending partition {Psend} and a
receiving partition {Precv} which is enforced when each is setting up
their own mapping of the partitions processors to the simulation box.
Each of {Psend} and {Precv} must be integers from 1 to Np, where Np is
the number of partitions you have defined via the "-partition
command-line switch"__Section_start.html#start_6.
A "dependency" means that the sending partition will create its 3d
logical grid as Px by Py by Pz and after it has done this, it will
send the Px,Py,Pz values to the receiving partition. The receiving
partition will wait to receive these values before creating its own 3d
logical grid and will use the sender's Px,Py,Pz values as a
constraint. The nature of the constraint is determined by the
{cstyle} argument.
For a {cstyle} of {multiple}, each dimension of the sender's processor
grid is required to be an integer multiple of the corresponding
dimension in the receiver's processor grid. This is a requirement of
the "run_style verlet/split"_run_style.html command.
For example, assume the sending partition creates a 4x6x10 grid = 240
processor grid. If the receiving partition is running on 80
processors, it could create a 4x2x10 grid, but it will not create a
2x4x10 grid, since in the y-dimension, 6 is not an integer multiple of
4.
:line
Note that you can use the "partition"_partition.html command to
specify different processor grids for different partitions, e.g.
partition yes 1 processors 4 4 4
partition yes 2 processors 2 3 2 :pre
IMPORTANT NOTE: If you use the "partition"_partition.html command to
invoke different "processsors" commands on different partitions, and
you also use the {part} keyword, then you must insure that both the
sending and receiving partitions invoke the "processors" command that
connects the 2 partitions via the {part} keyword. LAMMPS cannot
easily check for this, but your simulation will likely hang in its
setup phase if this error has been made.
[Restrictions:]
This command cannot be used after the simulation box is defined by a