qmp query-blockstats provides stats info for write/read/flush ops.
Patches 1-5 implement the similar for discard (unmap) command for scsi
and ide disks.
Discard stat "unmap_ops / unmap_bytes" is supposed to account the ops that
have completed without an error.
However, discard operation is advisory. Specifically,
- common block layer ignores ENOTSUP error code.
That might be returned if the block driver does not support discard,
or discard has been configured to be ignored.
- format drivers such as qcow2 may ignore discard if they were configured
to ignore that, or if the corresponding area is already marked unused
(unallocated / zero clusters).
And what is actually useful is the number of bytes actually discarded
down on the host filesystem.
To achieve that, driver-specific statistics has been added to blockstats
(patch 7).
With patch 6, file-posix driver accounts discard operations on its level too.
query-blockstat result:
(note the difference between blockdevice unmap and file discard stats. qcow2
sends a few ops down to the file as the clusters are actually unallocated
on qcow2 level)
{"return": [
{"device": "drive-scsi0-0-0-0"
"parent": {
"stats": {
"unmap_operations": 0
"unmap_merged": 0
"flush_total_time_ns": 0
"wr_highest_offset": 8111718400
[..]
"invalid_wr_operations": 0
"invalid_rd_operations": 0}
"node-name": "#block047"
"driver_stats": {
"type": "file"
"data": {
"discard_bytes_ok": 1572864
"discard_nb_failed": 0
"discard_nb_ok": 5}}}
"stats": {
"unmap_operations": 472
"unmap_merged": 0
"flush_total_time_ns": 44530540
"wr_highest_offset": 7106662400
"wr_total_time_ns": 45518856
"failed_wr_operations": 0
"failed_rd_operations": 0
"wr_merged": 0
"wr_bytes": 889856
"timed_stats": []
"failed_unmap_operations": 0
"failed_flush_operations": 0
"account_invalid": true
"rd_total_time_ns": 3306264098
"invalid_unmap_operations": 0
"flush_operations": 18
"wr_operations": 120
"unmap_bytes": 12312014848
"rd_merged": 0
"rd_bytes": 137103360
"unmap_total_time_ns": 22664692
"invalid_flush_operations": 0
"account_failed": true
"idle_time_ns": 437316567
"rd_operations": 5636
"invalid_wr_operations": 0
"invalid_rd_operations": 0}
"node-name": "#block128"}
{"device": "drive-ide0-0-0"
[..]
Anton Nefedov (7):
qapi: add unmap to BlockDeviceStats
ide: account UNMAP (TRIM) operations
scsi: store unmap offset and nb_sectors in request struct
scsi: move unmap error checking to the complete callback
scsi: account unmap operations
file-posix: account discard operations
qapi: query-blockstat: add driver specific file-posix stats
qapi/block-core.json | 57 ++++++++++++++++++++++++++++++++++++++++++++++
include/block/accounting.h | 1 +
include/block/block.h | 1 +
include/block/block_int.h | 1 +
block.c | 9 ++++++++
block/file-posix.c | 42 ++++++++++++++++++++++++++++++++--
block/qapi.c | 11 +++++++++
hw/ide/core.c | 12 ++++++++++
hw/scsi/scsi-disk.c | 29 ++++++++++++++---------
9 files changed, 150 insertions(+), 13 deletions(-)