Avoiding recompilation

1

Hi,
I am planning to run a bunch of short atmospheric model simulations which only differ in some namelist parameters. For a short atmospheric model simulation, running fcm_make_um2 takes a large fraction of the total run time. Is there a way of speeding this up? For example, using an existing binary?
ta
Simon

2

Hi Simon,

You can use prebuilds.
In the suite.rc file set the PREBUILD environment variable to point to the fcm_make_um directory on PUMA2 of the first suite.

E.g. to use the build from a suite called u-aa123 add the 2 lines indicated by <== Add line

    .....
    {% if SITE in DBLE_FCMUM %}
    [[fcm_make_um]]
        inherit = RUN_MAIN, EXTRACT_RESOURCE, UMBUILD
        [[[environment]]]                                                     <== Add line
            PREBUILD = /home/n02/n02/tetts/cylc-run/u-aa123/share/fcm_make_um      <== Add line
    [[fcm_make2_um]]
        inherit = RUN_MAIN, UMBUILD_RESOURCE, UMBUILD
    {% else %}
    ......

Cheers,
Ros.

1 Like
3

Hi Ros,
thanks for that. Just to check fcm_make2_um is what appears to take the time. Is adding PREBUILD to fcm_make_um telling it to install the prebuild stuff and then use that.
Simon

4

Hi Simon,

Yes, FCM knows where to find the corresponding fcm_make2_um directory.

Cheers,
Ros.

5

I must be doing something wrong…
test_case001_191477 (~tetts/rose_optclim/test_case001_191477 on puma) which has some other changes (scripts added to the graph and some parameter changes) but does have the following added:
## allow use of pre-build code,
[[[environment]]]
PREBUILD = /home/n02/n02/tetts/cylc-run/u-db898/share/fcm_make_um

But it seems to be compiling…as it is generating a bunch of .o files in /work/n02/n02/tetts/cylc-run/test_case001_191477/share/fcm_make_um/build-atmos/o/

Simon

6

Can you give me read access to your NVMe directory: /mnt/lustre/a2fs-nvme/work/n02/n02/tetts please?

7

Hi Simon,

Actually the suite is set up slightly differently. Remove the PREBUILD you added from the suite.rc file and you can just put the path in the panel ‘fcm_make_um → env → Basic compilation → prebuild’

Cheers,
Ros.

8

Great. I think I will go back to an earlier suite (which then gets programmatically modified) and do that. My suite dates from late 2023. Should I use that or grab the current AMIP UKESM suite and start with that? My suite is u-da865 and from the info comes from u-cj514/trunk@264964 – fixed problems.

Simon

9

Going to continue working with u-db898
And can I add itself ( /home/n02/n02/tetts/cylc-run/u-db898/share/fcm_make_um) to the prebuild and run that? If the prebuild doesn’t exist, will it make it or just fail…
Simon

10

A suite cannot point a prebuild to itself. If you try it, you’ll find it errors.

Cheers,
Ros.