Commit Graph

4 Commits

Author SHA1 Message Date
Ryan Moeller 20e4513c56 FreeBSD: Update usage of py-sysctl
py-sysctl now includes the CTLTYPE_NODE type nodes in the list returned
by sysctl.filter() on FreeBSD head.  It also provides descriptions now.

Eliminate the subprocess call to get descriptions, and filter out the
nodes so we only deal with values.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ryan Moeller <ryan@iXsystems.com>
Closes #11318
2020-12-23 14:34:59 -08:00
Ryan Moeller 3b79394bc9 arcstat: Add -a and -p options from FreeNAS
Added -a option to automatically print all valid statistics.
Added -p option to suppress scaling of printed data.

Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Authored by: Nick Principe <32284693+powernap@users.noreply.github.com>
Ported-by: Ryan Moeller <ryan@iXsystems.com>
Signed-off-by: Ryan Moeller <ryan@iXsystems.com>
Closes #11090
2020-10-30 16:02:11 -07:00
Matthew Ahrens 85ec5cbae2
Include scatter_chunk_waste in arc_size
The ARC caches data in scatter ABD's, which are collections of pages,
which are typically 4K.  Therefore, the space used to cache each block
is rounded up to a multiple of 4K.  The ABD subsystem tracks this wasted
memory in the `scatter_chunk_waste` kstat.  However, the ARC's `size` is
not aware of the memory used by this round-up, it only accounts for the
size that it requested from the ABD subsystem.

Therefore, the ARC is effectively using more memory than it is aware of,
due to the `scatter_chunk_waste`.  This impacts observability, e.g.
`arcstat` will show that the ARC is using less memory than it
effectively is.  It also impacts how the ARC responds to memory
pressure.  As the amount of `scatter_chunk_waste` changes, it appears to
the ARC as memory pressure, so it needs to resize `arc_c`.

If the sector size (`1<<ashift`) is the same as the page size (or
larger), there won't be any waste.  If the (compressed) block size is
relatively large compared to the page size, the amount of
`scatter_chunk_waste` will be small, so the problematic effects are
minimal.

However, if using 512B sectors (`ashift=9`), and the (compressed) block
size is small (e.g. `compression=on` with the default `volblocksize=8k`
or a decreased `recordsize`), the amount of `scatter_chunk_waste` can be
very large.  On a production system, with `arc_size` at a constant 50%
of memory, `scatter_chunk_waste` has been been observed to be 10-30% of
memory.

This commit adds `scatter_chunk_waste` to `arc_size`, and adds a new
`waste` field to `arcstat`.  As a result, the ARC's memory usage is more
observable, and `arc_c` does not need to be adjusted as frequently.

Reviewed-by: Pavel Zakharov <pavel.zakharov@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: George Wilson <gwilson@delphix.com>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Signed-off-by: Matthew Ahrens <mahrens@delphix.com>
Closes #10701
2020-08-17 20:04:04 -07:00
Arvind Sankar 38e2e9ce83 Centralize variable substitution
A bunch of places need to edit files to incorporate the configured paths
i.e. bindir, sbindir etc. Move this logic into a common file.

Create arc_summary by copying arc_summary[23] as appropriate at build
time instead of install time.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Closes #10559
2020-07-14 17:33:44 -07:00