Speed up bigmem compression tests in dry mode

[serhiy-storchaka]

Has this already been discussed elsewhere?

This is a minor feature, which does not need previous discussion elsewhere

Links to previous discussion of this feature:

No response

Proposal:

Three bigmem tests test compression of large (slightly more than 4 GiB) data. They create 10 MiB of random data and write them multiple times. When run in "dry run" mode (by default) they only write a small sample. But they generate the whole 10 MiB of random data, and it takes time.

The proposed PR makes them only generating small number of random bytes for dry run. This speeds up running tests in default mode.

Linked PRs

• gh-108418: Speed up bigmem compression tests in dry mode #108419
• [3.12] gh-108418: Speed up bigmem compression tests in dry mode (GH-108419) #108473
• [3.11] gh-108418: Speed up bigmem compression tests in dry mode (GH-108419) #108481