Add a script which can be used to generate device-specific iocost
linear model coefficients.
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
---
Documentation/admin-guide/cgroup-v2.rst | 3 +
block/blk-iocost.c | 3 +
tools/cgroup/iocost_coef_gen.py | 178 ++++++++++++++++++++++++
3 files changed, 184 insertions(+)
create mode 100644 tools/cgroup/iocost_coef_gen.py
diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
index aff812631c40..e683c51f7ba3 100644
--- a/Documentation/admin-guide/cgroup-v2.rst
+++ b/Documentation/admin-guide/cgroup-v2.rst
@@ -1519,6 +1519,9 @@ IO Interface Files
The IO cost model isn't expected to be accurate in absolute
sense and is scaled to the device behavior dynamically.
+ If needed, tools/cgroup/iocost_coef_gen.py can be used to
+ generate device-specific coefficients.
+
io.weight
A read-write flat-keyed file which exists on non-root cgroups.
The default is "default 100".
diff --git a/block/blk-iocost.c b/block/blk-iocost.c
index d608c5aa84ed..a8d5c90de0c2 100644
--- a/block/blk-iocost.c
+++ b/block/blk-iocost.c
@@ -46,6 +46,9 @@
* If needed, tools/cgroup/iocost_coef_gen.py can be used to generate
* device-specific coefficients.
*
+ * If needed, tools/cgroup/iocost_coef_gen.py can be used to generate
+ * device-specific coefficients.
+ *
* 2. Control Strategy
*
* The device virtual time (vtime) is used as the primary control metric.
diff --git a/tools/cgroup/iocost_coef_gen.py b/tools/cgroup/iocost_coef_gen.py
new file mode 100644
index 000000000000..df17a2ae80e5
--- /dev/null
+++ b/tools/cgroup/iocost_coef_gen.py
@@ -0,0 +1,178 @@
+#!/usr/bin/env python3
+#
+# Copyright (C) 2019 Tejun Heo <tj@xxxxxxxxxx>
+# Copyright (C) 2019 Andy Newell <newella@xxxxxx>
+# Copyright (C) 2019 Facebook
+
+desc = """
+Generate linear IO cost model coefficients used by the blk-iocost
+controller. If the target raw testdev is specified, destructive tests
+are performed against the whole device; otherwise, on
+./iocost-coef-fio.testfile. The result can be written directly to
+/sys/fs/cgroup/io.cost.model.
+
+On high performance devices, --numjobs > 1 is needed to achieve
+saturation.
+
+See Documentation/admin-guide/cgroup-v2.rst and block/blk-iocost.c
+for more details.
+"""
+
+import argparse
+import re
+import json
+import glob
+import os
+import sys
+import atexit
+import shutil
+import tempfile
+import subprocess
+
+parser = argparse.ArgumentParser(description=desc,
+ formatter_class=argparse.RawTextHelpFormatter)
+parser.add_argument('--testdev', metavar='DEV',
+ help='Raw block device to use for testing, ignores --testfile-size')
+parser.add_argument('--testfile-size-gb', type=float, metavar='GIGABYTES', default=16,
+ help='Testfile size in gigabytes (default: %(default)s)')
+parser.add_argument('--duration', type=int, metavar='SECONDS', default=120,
+ help='Individual test run duration in seconds (default: %(default)s)')
+parser.add_argument('--seqio-block-mb', metavar='MEGABYTES', type=int, default=128,
+ help='Sequential test block size in megabytes (default: %(default)s)')
+parser.add_argument('--seq-depth', type=int, metavar='DEPTH', default=64,
+ help='Sequential test queue depth (default: %(default)s)')
+parser.add_argument('--rand-depth', type=int, metavar='DEPTH', default=64,
+ help='Random test queue depth (default: %(default)s)')
+parser.add_argument('--numjobs', type=int, metavar='JOBS', default=1,
+ help='Number of parallel fio jobs to run (default: %(default)s)')
+parser.add_argument('--quiet', action='store_true')
+parser.add_argument('--verbose', action='store_true')
+
+def info(msg):
+ if not args.quiet:
+ print(msg)
+
+def dbg(msg):
+ if args.verbose and not args.quiet:
+ print(msg)
+
+# determine ('DEVNAME', 'MAJ:MIN') for @path
+def dir_to_dev(path):
+ # find the block device the current directory is on
+ devname = subprocess.run(f'findmnt -nvo SOURCE -T{path}',
+ stdout=subprocess.PIPE, shell=True).stdout
+ devname = os.path.basename(devname).decode('utf-8').strip()
+
+ # partition -> whole device
+ parents = glob.glob('/sys/block/*/' + devname)
+ if len(parents):
+ devname = os.path.basename(os.path.dirname(parents[0]))
+ rdev = os.stat(f'/dev/{devname}').st_rdev
+ return (devname, f'{os.major(rdev)}:{os.minor(rdev)}')
+
+def create_testfile(path, size):
+ global args
+
+ if os.path.isfile(path) and os.stat(path).st_size == size:
+ return
+
+ info(f'Creating testfile {path}')
+ subprocess.check_call(f'rm -f {path}', shell=True)
+ subprocess.check_call(f'touch {path}', shell=True)
+ subprocess.call(f'chattr +C {path}', shell=True)
+ subprocess.check_call(
+ f'pv -s {size} -pr /dev/urandom {"-q" if args.quiet else ""} | '
+ f'dd of={path} count={size} '
+ f'iflag=count_bytes,fullblock oflag=direct bs=16M status=none',
+ shell=True)
+
+def run_fio(testfile, duration, iotype, iodepth, blocksize, jobs):
+ global args
+
+ eta = 'never' if args.quiet else 'always'
+ outfile = tempfile.NamedTemporaryFile()
+ cmd = (f'fio --direct=1 --ioengine=libaio --name=coef '
+ f'--filename={testfile} --runtime={round(duration)} '
+ f'--readwrite={iotype} --iodepth={iodepth} --blocksize={blocksize} '
+ f'--eta={eta} --output-format json --output={outfile.name} '
+ f'--time_based --numjobs={jobs}')
+ if args.verbose:
+ dbg(f'Running {cmd}')
+ subprocess.check_call(cmd, shell=True)
+ with open(outfile.name, 'r') as f:
+ d = json.loads(f.read())
+ return sum(j['read']['bw_bytes'] + j['write']['bw_bytes'] for j in d['jobs'])
+
+def restore_elevator_nomerges():
+ global elevator_path, nomerges_path, elevator, nomerges
+
+ info(f'Restoring elevator to {elevator} and nomerges to {nomerges}')
+ with open(elevator_path, 'w') as f:
+ f.write(elevator)
+ with open(nomerges_path, 'w') as f:
+ f.write(nomerges)
+
+
+args = parser.parse_args()
+
+missing = False
+for cmd in [ 'findmnt', 'pv', 'dd', 'fio' ]:
+ if not shutil.which(cmd):
+ print(f'Required command "{cmd}" is missing', file=sys.stderr)
+ missing = True
+if missing:
+ sys.exit(1)
+
+if args.testdev:
+ devname = os.path.basename(args.testdev)
+ rdev = os.stat(f'/dev/{devname}').st_rdev
+ devno = f'{os.major(rdev)}:{os.minor(rdev)}'
+ testfile = f'/dev/{devname}'
+ info(f'Test target: {devname}({devno})')
+else:
+ devname, devno = dir_to_dev('.')
+ testfile = 'iocost-coef-fio.testfile'
+ testfile_size = int(args.testfile_size_gb * 2 ** 30)
+ create_testfile(testfile, testfile_size)
+ info(f'Test target: {testfile} on {devname}({devno})')
+
+elevator_path = f'/sys/block/{devname}/queue/scheduler'
+nomerges_path = f'/sys/block/{devname}/queue/nomerges'
+
+with open(elevator_path, 'r') as f:
+ elevator = re.sub(r'.*\[(.*)\].*', r'\1', f.read().strip())
+with open(nomerges_path, 'r') as f:
+ nomerges = f.read().strip()
+
+info(f'Temporarily disabling elevator and merges')
+atexit.register(restore_elevator_nomerges)
+with open(elevator_path, 'w') as f:
+ f.write('none')
+with open(nomerges_path, 'w') as f:
+ f.write('1')
+
+info('Determining rbps...')
+rbps = run_fio(testfile, args.duration, 'read',
+ 1, args.seqio_block_mb * (2 ** 20), args.numjobs)
+info(f'\nrbps={rbps}, determining rseqiops...')
+rseqiops = round(run_fio(testfile, args.duration, 'read',
+ args.seq_depth, 4096, args.numjobs) / 4096)
+info(f'\nrseqiops={rseqiops}, determining rrandiops...')
+rrandiops = round(run_fio(testfile, args.duration, 'randread',
+ args.rand_depth, 4096, args.numjobs) / 4096)
+info(f'\nrrandiops={rrandiops}, determining wbps...')
+wbps = run_fio(testfile, args.duration, 'write',
+ 1, args.seqio_block_mb * (2 ** 20), args.numjobs)
+info(f'\nwbps={wbps}, determining wseqiops...')
+wseqiops = round(run_fio(testfile, args.duration, 'write',
+ args.seq_depth, 4096, args.numjobs) / 4096)
+info(f'\nwseqiops={wseqiops}, determining wrandiops...')
+wrandiops = round(run_fio(testfile, args.duration, 'randwrite',
+ args.rand_depth, 4096, args.numjobs) / 4096)
+info(f'\nwrandiops={wrandiops}')
+restore_elevator_nomerges()
+atexit.unregister(restore_elevator_nomerges)
+info('')
+
+print(f'{devno} rbps={rbps} rseqiops={rseqiops} rrandiops={rrandiops} '
+ f'wbps={wbps} wseqiops={wseqiops} wrandiops={wrandiops}')
--
2.17.1
