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authorStefan Raspl <raspl@de.ibm.com>2020-04-02 11:57:04 +0300
committerPaolo Bonzini <pbonzini@redhat.com>2020-04-21 16:13:12 +0300
commit3754afe7cf7cc3693a9c9ff795e9bd97175ca639 (patch)
tree8f2c57b6dda1b245fe3436bd762f0f5f5ecafe30
parentda1fda288943c37de8e1513b98f6dda40c8cd421 (diff)
downloadlinux-3754afe7cf7cc3693a9c9ff795e9bd97175ca639.tar.xz
tools/kvm_stat: Add command line switch '-L' to log to file
To integrate with logrotate, we have a signal handler that will re-open the logfile. Assuming we have a systemd unit file with ExecStart=kvm_stat -dtc -s 10 -L /var/log/kvm_stat.csv ExecReload=/bin/kill -HUP $MAINPID and a logrotate config featuring postrotate /bin/systemctl reload kvm_stat.service endscript Then the overall flow will look like this: (1) systemd starts kvm_stat, logging to A. (2) At some point, logrotate runs, moving A to B. kvm_stat continues to write to B at this point. (3) After rotating, logrotate restarts the kvm_stat unit via systemctl. (4) The kvm_stat unit sends a SIGHUP to kvm_stat, finally making it switch over to writing to A again. Note that in order to keep the structure of the cvs output in tact, we make sure to, in contrast to the standard log format, only write the header once at the beginning of a file. This implies that the header is suppressed when appending to an existing file. Unlike with the standard format, where we append to an existing file by starting out with a header. Signed-off-by: Stefan Raspl <raspl@de.ibm.com> Message-Id: <20200402085705.61155-3-raspl@linux.ibm.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
-rwxr-xr-xtools/kvm/kvm_stat/kvm_stat70
-rw-r--r--tools/kvm/kvm_stat/kvm_stat.txt11
2 files changed, 68 insertions, 13 deletions
diff --git a/tools/kvm/kvm_stat/kvm_stat b/tools/kvm/kvm_stat/kvm_stat
index d6cced4e1ef4..d199a3694be8 100755
--- a/tools/kvm/kvm_stat/kvm_stat
+++ b/tools/kvm/kvm_stat/kvm_stat
@@ -32,6 +32,7 @@ import resource
import struct
import re
import subprocess
+import signal
from collections import defaultdict, namedtuple
from functools import reduce
from datetime import datetime
@@ -228,6 +229,8 @@ IOCTL_NUMBERS = {
'RESET': 0x00002403,
}
+signal_received = False
+
ENCODING = locale.getpreferredencoding(False)
TRACE_FILTER = re.compile(r'^[^\(]*$')
@@ -1523,26 +1526,64 @@ class CSVFormat(object):
def log(stats, opts, frmt, keys):
"""Prints statistics as reiterating key block, multiple value blocks."""
+ global signal_received
line = 0
banner_repeat = 20
- banner_printed = False
-
+ f = None
+
+ def do_banner(opts):
+ nonlocal f
+ if opts.log_to_file:
+ if not f:
+ try:
+ f = open(opts.log_to_file, 'a')
+ except (IOError, OSError):
+ sys.exit("Error: Could not open file: %s" %
+ opts.log_to_file)
+ if isinstance(frmt, CSVFormat) and f.tell() != 0:
+ return
+ print(frmt.get_banner(), file=f or sys.stdout)
+
+ def do_statline(opts, values):
+ statline = datetime.now().strftime("%Y-%m-%d %H:%M:%S") + \
+ frmt.get_statline(keys, values)
+ print(statline, file=f or sys.stdout)
+
+ do_banner(opts)
+ banner_printed = True
while True:
try:
time.sleep(opts.set_delay)
- if line % banner_repeat == 0 and not banner_printed:
- print(frmt.get_banner())
+ if signal_received:
+ banner_printed = True
+ line = 0
+ f.close()
+ do_banner(opts)
+ signal_received = False
+ if (line % banner_repeat == 0 and not banner_printed and
+ not (opts.log_to_file and isinstance(frmt, CSVFormat))):
+ do_banner(opts)
banner_printed = True
values = stats.get()
if (not opts.skip_zero_records or
any(values[k].delta != 0 for k in keys)):
- print(datetime.now().strftime("%Y-%m-%d %H:%M:%S") +
- frmt.get_statline(keys, values))
+ do_statline(opts, values)
line += 1
banner_printed = False
except KeyboardInterrupt:
break
+ if opts.log_to_file:
+ f.close()
+
+
+def handle_signal(sig, frame):
+ global signal_received
+
+ signal_received = True
+
+ return
+
def is_delay_valid(delay):
"""Verify delay is in valid value range."""
@@ -1615,7 +1656,7 @@ Press any other key to refresh statistics immediately.
argparser.add_argument('-c', '--csv',
action='store_true',
default=False,
- help='log in csv format - requires option -l/--log',
+ help='log in csv format - requires option -l/-L',
)
argparser.add_argument('-d', '--debugfs',
action='store_true',
@@ -1643,6 +1684,11 @@ Press any other key to refresh statistics immediately.
default=False,
help='run in logging mode (like vmstat)',
)
+ argparser.add_argument('-L', '--log-to-file',
+ type=str,
+ metavar='FILE',
+ help="like '--log', but logging to a file"
+ )
argparser.add_argument('-p', '--pid',
type=int,
default=0,
@@ -1666,10 +1712,10 @@ Press any other key to refresh statistics immediately.
help='omit records with all zeros in logging mode',
)
options = argparser.parse_args()
- if options.csv and not options.log:
+ if options.csv and not (options.log or options.log_to_file):
sys.exit('Error: Option -c/--csv requires -l/--log')
- if options.skip_zero_records and not options.log:
- sys.exit('Error: Option -z/--skip-zero-records requires -l/--log')
+ if options.skip_zero_records and not (options.log or options.log_to_file):
+ sys.exit('Error: Option -z/--skip-zero-records requires -l/-L')
try:
# verify that we were passed a valid regex up front
re.compile(options.fields)
@@ -1749,7 +1795,9 @@ def main():
sys.stdout.write(' ' + '\n '.join(sorted(set(event_list))) + '\n')
sys.exit(0)
- if options.log:
+ if options.log or options.log_to_file:
+ if options.log_to_file:
+ signal.signal(signal.SIGHUP, handle_signal)
keys = sorted(stats.get().keys())
if options.csv:
frmt = CSVFormat(keys)
diff --git a/tools/kvm/kvm_stat/kvm_stat.txt b/tools/kvm/kvm_stat/kvm_stat.txt
index 24296dccc00a..feaf46451e83 100644
--- a/tools/kvm/kvm_stat/kvm_stat.txt
+++ b/tools/kvm/kvm_stat/kvm_stat.txt
@@ -65,8 +65,10 @@ OPTIONS
run in batch mode for one second
-c::
---csv=<file>::
- log in csv format - requires option -l/--log
+--csv::
+ log in csv format. Requires option -l/--log or -L/--log-to-file.
+ When used with option -L/--log-to-file, the header is only ever
+ written to start of file to preserve the format.
-d::
--debugfs::
@@ -92,6 +94,11 @@ OPTIONS
--log::
run in logging mode (like vmstat)
+
+-L<file>::
+--log-to-file=<file>::
+ like -l/--log, but logging to a file. Appends to existing files.
+
-p<pid>::
--pid=<pid>::
limit statistics to one virtual machine (pid)