new checkpointing mode

examples/__MULTI_BLOCK_GEOMETRY/kovasznay_flow/dns.in

@@ -2,7 +2,7 @@
 1. 1. .025 ! uref, lref, rey
 50000 100. 0.1 ! nstep,time_max,tw_max
 T F F ! stop_type(1:3)
-F T  ! restart,is_overwrite_save
+F T 0 ! restart,is_overwrite_save,nsaves_max
 10 10 200000 50000000 100 200 ! icheck, iout0d, iout1d, iout2d, iout3d, isave
 0. 0. 0. ! bforce(1:3)
 4 ! nthreadsmax

src/INFO_INPUT.md

@@ -69,6 +69,8 @@ a checkpoint file `fld.bin` will be saved before the simulation is terminated.
 
 `is_overwrite_save`, if true, overwrites the checkpoint file `fld.bin` at every save; if false, a symbolic link is created which makes `fld.bin` point to the last checkpoint file with name `fld_???????.bin`. In the latter case, to restart a run from a different checkpoint one just has to point the file `fld.bin` to the right file, e.g.: ` ln -sf fld_0000100.bin fld.bin`.
 
+`nsaves_max` limits the number of saved checkpoint files, if `is_over_write_save` is false; a value of `0` or any negative integer corresponds to no limit, and the code uses the file format described above; otherwise, only `nsaves_max` checkpoint files are saved, with the oldest save being overwritten when the number of saved checkpoints exceeds this threshold; in this case, files with a format `fld_????.bin` are saved (with `????` denoting the saved file number), with `fld.bin` pointing to the last checkpoint file as described above; moreover, a file `log_saves.out` records information about the time step number and physical time corresponding to each saved file number.
+
 ---
 
 ~~~

src/dns.in

@@ -2,7 +2,7 @@
 1. 1. 100. ! uref, lref, rey
 100 100. 0.1 ! nstep,time_max,tw_max
 T F F ! stop_type(1:3)
-F T  ! restart,is_overwrite_save
+F T 0 ! restart,is_overwrite_save,nsaves_max
 10 10 200000 50000000 10 20 ! icheck, iout0d, iout1d, iout2d, iout3d, isave
 0. 0. 0. ! bforce(1:3)
 4 ! nthreadsmax

src/main.f90

@@ -38,7 +38,7 @@ program snac
  rkcoeff, &
  cfl,dtmin,uref,lref,rey,visc, &
  nstep,time_max,tw_max,stop_type, &
- restart,is_overwrite_save,  &
+ restart,is_overwrite_save,nsaves_max, &
  nthreadsmax, &
  icheck,iout0d,iout1d,iout2d,iout3d,isave, &
  dims,lo,hi,lmin,lmax, &
@@ -171,10 +171,12 @@ program snac
  real(rp), dimension(100) :: var
  character(len=3 ) :: cblock
  character(len=7 ) :: fldnum
+ character(len=4 ) :: chkptnum
  character(len=100) :: filename
  integer :: iunit
  !
  real(rp) :: twi,tw
+ integer :: savecounter
  logical :: is_done,kill
 #ifdef _TIMING
  real(rp) :: dt12,dt12av,dt12min,dt12max
@@ -184,6 +186,7 @@ program snac
  call MPI_INIT()
  call MPI_COMM_RANK(MPI_COMM_WORLD, myid)
  twi = MPI_WTIME()
+ savecounter = 0
  !
  ! read parameter file
  !
@@ -1065,7 +1068,16 @@ program snac
  if(is_overwrite_save) then
  filename = 'fld_b_'//cblock//'.bin'
  else
- filename = 'fld_'//fldnum//'_b_'//cblock//'.bin'
+ if(nsaves_max > 0) then
+ if(savecounter >= nsaves_max) savecounter = 0
+ savecounter = savecounter + 1
+ write(chkptnum,'(i4.4)') savecounter
+ filename = 'fld_'//chkptnum//'_b_'//cblock//'.bin'
+ var(1) = 1.*istep
+ var(2) = time
+ var(3) = 1.*savecounter
+ call out0d(trim(datadir)//'log_saves.out',3,myid,var)
+ endif
  end if
  call load('w',trim(datadir)//trim(filename),comm_block,ng,[1,1,1],lo_1,hi_1,u,v,w,p,po,time,istep)
  if(.not.is_overwrite_save) then

src/param.f90

@@ -27,6 +27,7 @@ module mod_param
 real(rp) :: time_max,tw_max
 logical , dimension(3) :: stop_type
 logical :: restart,is_overwrite_save
+integer :: nsaves_max
 integer :: icheck,iout0d,iout1d,iout2d,iout3d,isave
 real(rp), dimension(3) :: bforce
 integer :: nthreadsmax
@@ -69,7 +70,7 @@ subroutine read_input()
  read(iunit,*) uref,lref,rey
  read(iunit,*) nstep, time_max,tw_max
  read(iunit,*) stop_type(1),stop_type(2),stop_type(3)
- read(iunit,*) restart,is_overwrite_save
+ read(iunit,*) restart,is_overwrite_save,nsaves_max
  read(iunit,*) icheck,iout0d,iout1d,iout2d,iout3d,isave
  read(iunit,*) bforce(1),bforce(2),bforce(3)
  read(iunit,*) nthreadsmax

tests/lid_driven_cavity/dns.in

@@ -2,7 +2,7 @@
 1. 1. 1000. ! uref, lref, rey
 1500 100. 0.1 ! nstep,time_max,tw_max
 T F F ! stop_type(1:3)
-F T ! restart,is_overwrite_save
+F T 0  ! restart,is_overwrite_save,nsaves_max
 10 10 20 500 500 2000 ! icheck, iout0d, iout1d, iout2d, iout3d, isave
 0. 0. 0. ! bforce(1:3)
 4 ! nthreadsmax