zfs.4: Document the actual default for zfs_txg_history

[0mp]

Motivation and Context

zfs.4 documents the default of zfs_txg_history to be 0. This is incorrect. The default is 100.

Description

$ grep zfs_txg_history module/zfs/spa_stats.c
static uint_t zfs_txg_history = 100;
        if (zfs_txg_history == 0 && shl->size == 0)
        spa_txg_history_truncate(shl, zfs_txg_history);
        if (zfs_txg_history == 0)
        if (zfs_txg_history == 0)
        if (zfs_txg_history == 0)
        if (zfs_txg_history == 0) {

Sponsored-by: Klara, Inc.
Sponsored-by: Wasabi Technology, Inc.

How Has This Been Tested?

The manual renders fine.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Performance enhancement (non-breaking change which improves efficiency)
• Code cleanup (non-breaking change which makes code smaller or more readable)
• Breaking change (fix or feature that would cause existing functionality to change)
• Library ABI change (libzfs, libzfs_core, libnvpair, libuutil and libzfsbootenv)
• Documentation (a change to man pages or other documentation)

Checklist:

• My code follows the OpenZFS code style requirements.
• I have updated the documentation accordingly.
• I have read the contributing document.
• I have added tests to cover my changes.
• I have run the ZFS Test Suite with this change applied.
• All commit messages are properly formatted and contain Signed-off-by.

[tonyhutter]

You are correct, thanks for the fix:

$ cat /sys/module/zfs/parameters/zfs_txg_history 
100