File add-command-line-switch-L-to-log-file.patch of Package kvm_stat
commit 3754afe7cf7cc3693a9c9ff795e9bd97175ca639 Author: Stefan Raspl <[email protected]> Date: Thu Apr 2 10:57:04 2020 +0200 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 <[email protected]> Message-Id: <[email protected]> Signed-off-by: Paolo Bonzini <[email protected]> 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)
