tools/compactsnoop.py - platform/external/bcc - Git at Google

 #!/usr/bin/env python
 # @lint-avoid-python-3-compatibility-imports
 #
 # compactsnoop  Trace compact zone and print details including issuing PID.
 #       For Linux, uses BCC, eBPF.
 #
 # This uses in-kernel eBPF maps to cache process details (PID and comm) by
 # compact zone begin, as well as a starting timestamp for calculating
 # latency.
 #
 # Copyright (c) 2019 Wenbo Zhang
 # Licensed under the Apache License, Version 2.0 (the "License")
 #
 # 11-NOV-2019   Wenbo Zhang   Created this.

 from __future__ import print_function
 from bcc import BPF
 import argparse
 import platform
 from datetime import datetime, timedelta
 import sys

 # arguments
 examples = """examples:
     ./compactsnoop          # trace all compact stall
     ./compactsnoop -T       # include timestamps
     ./compactsnoop -d 10    # trace for 10 seconds only
     ./compactsnoop -K       # output kernel stack trace
     ./compactsnoop -e       # show extended fields
 """

 parser = argparse.ArgumentParser(
     description="Trace compact zone",
     formatter_class=argparse.RawDescriptionHelpFormatter,
     epilog=examples,
 )
 parser.add_argument("-T", "--timestamp", action="store_true",
         help="include timestamp on output")
 parser.add_argument("-p", "--pid", help="trace this PID only")
 parser.add_argument("-d", "--duration",
         help="total duration of trace in seconds")
 parser.add_argument("-K", "--kernel-stack", action="store_true",
         help="output kernel stack trace")
 parser.add_argument("-e", "--extended_fields", action="store_true",
         help="show system memory state")
 parser.add_argument("--ebpf", action="store_true", help=argparse.SUPPRESS)
 args = parser.parse_args()
 debug = 0
 if args.duration:
     args.duration = timedelta(seconds=int(args.duration))

 NO_EXTENDED = """
 #ifdef EXTNEDED_FIELDS
 #undef EXTNEDED_FIELDS
 #endif
 """

 EXTENDED = """
 #define EXTNEDED_FIELDS    1
 """

 bpf_text = """
 #include <uapi/linux/ptrace.h>
 #include <linux/sched.h>
 #include <linux/mmzone.h>
 #include <linux/compaction.h>

 struct val_t {
     int nid;
     int idx;
     int order;
     int sync;
 #ifdef EXTNEDED_FIELDS
     int fragindex;
     int low;
     int min;
     int high;
     int free;
 #endif
     u64 ts;    // compaction begin time
 };

 struct data_t {
     u32 pid;
     u32 tid;
     int nid;
     int idx;
     int order;
     u64 delta;
     u64 ts;    // compaction end time
     int sync;
 #ifdef EXTNEDED_FIELDS
     int fragindex;
     int low;
     int min;
     int high;
     int free;
 #endif
     int status;
     int stack_id;
     char comm[TASK_COMM_LEN];
 };

 BPF_HASH(start, u64, struct val_t);
 BPF_PERF_OUTPUT(events);
 BPF_STACK_TRACE(stack_traces, 2048);

 #ifdef CONFIG_NUMA
 static inline int zone_to_nid_(struct zone *zone)
 {
     int node;
     bpf_probe_read_kernel(&node, sizeof(node), &zone->node);
     return node;
 }
 #else
 static inline int zone_to_nid_(struct zone *zone)
 {
     return 0;
 }
 #endif

 // #define zone_idx(zone) ((zone) - (zone)->zone_pgdat->node_zones)
 static inline int zone_idx_(struct zone *zone)
 {
     struct pglist_data *zone_pgdat = NULL;
     bpf_probe_read_kernel(&zone_pgdat, sizeof(zone_pgdat), &zone->zone_pgdat);
     return ((u64)zone - (u64)zone_pgdat->node_zones)/sizeof(struct zone);
 }

 #ifdef EXTNEDED_FIELDS
 static inline void get_all_wmark_pages(struct zone *zone, struct val_t *valp)
 {
     u64 _watermark[NR_WMARK] = {};
     u64 watermark_boost = 0;

     bpf_probe_read_kernel(&_watermark, sizeof(_watermark), &zone->_watermark);
     bpf_probe_read_kernel(&watermark_boost, sizeof(watermark_boost),
                     &zone->watermark_boost);
     valp->min = _watermark[WMARK_MIN] + watermark_boost;
     valp->low = _watermark[WMARK_LOW] + watermark_boost;
     valp->high = _watermark[WMARK_HIGH] + watermark_boost;
     bpf_probe_read_kernel(&valp->free, sizeof(valp->free),
                     &zone->vm_stat[NR_FREE_PAGES]);
 }
 #endif

 static inline void submit_event(void *ctx, int status)
 {
     struct data_t data = {};
     u64 ts = bpf_ktime_get_ns();
     u64 id = bpf_get_current_pid_tgid();
     struct val_t *valp = start.lookup(&id);
     if (valp == NULL) {
         // missed entry
         return;
     }

     data.delta = ts - valp->ts;
     data.ts = ts / 1000;
     data.pid = id >> 32;
     data.tid = id;
     bpf_get_current_comm(&data.comm, sizeof(data.comm));
     data.nid = valp->nid;
     data.idx = valp->idx;
     data.order = valp->order;
     data.sync = valp->sync;

 #ifdef EXTNEDED_FIELDS
     data.fragindex = valp->fragindex;
     data.min = valp->min;
     data.low = valp->low;
     data.high = valp->high;
     data.free = valp->free;
 #endif

     data.status = status;
     data.stack_id = stack_traces.get_stackid(ctx, 0);

     events.perf_submit(ctx, &data, sizeof(data));

     start.delete(&id);
 }

 #ifdef EXTNEDED_FIELDS
 int trace_fragmentation_index_return(struct pt_regs *ctx)
 {
     struct val_t val = { };
     int ret = PT_REGS_RC(ctx);
     u64 id = bpf_get_current_pid_tgid();
     PID_FILTER
     val.fragindex = ret;
     start.update(&id, &val);
     return 0;
 }
 #endif

 static inline void fill_compact_info(struct val_t *valp,
                                      struct zone *zone,
                                      int order)
 {
     valp->nid = zone_to_nid_(zone);
     valp->idx = zone_idx_(zone);
     valp->order = order;
 }

 RAW_TRACEPOINT_PROBE(mm_compaction_suitable)
 {
     // TP_PROTO(struct zone *zone, int order, int ret)
     struct zone *zone = (struct zone *)ctx->args[0];
     struct val_t val = { };
     int order = (int)ctx->args[1];
     int ret = (int)ctx->args[2];
     u64 id;

     if(ret != COMPACT_CONTINUE)
         return 0;

     id = bpf_get_current_pid_tgid();
     PID_FILTER

 #ifdef EXTNEDED_FIELDS
     struct val_t *valp = start.lookup(&id);
     if (valp == NULL) {
         // missed entry or order <= PAGE_ALLOC_COSTLY_ORDER, eg:
         // manual trigger echo 1 > /proc/sys/vm/compact_memory
         val.fragindex = -1000;
         valp = &val;
     }
     fill_compact_info(valp, zone, order);
     get_all_wmark_pages(zone, valp);
     start.update(&id, valp);
 #else
     fill_compact_info(&val, zone, order);
     start.update(&id, &val);
 #endif

     return 0;
 }

 TRACEPOINT_PROBE(compaction, mm_compaction_begin)
 {
     bool sync = args->sync;

     u64 id = bpf_get_current_pid_tgid();
     struct val_t *valp = start.lookup(&id);
     if (valp == NULL) {
         // missed entry
         return 0;
     }

     valp->ts = bpf_ktime_get_ns();
     valp->sync = sync;
     return 0;
 }

 TRACEPOINT_PROBE(compaction, mm_compaction_end)
 {
     submit_event(args, args->status);
     return 0;
 }
 """

 if platform.machine() != 'x86_64' and platform.machine() != 'ppc64le':
     print("""
           Currently only support x86_64 and power servers, if you want
           to use it on other platforms(including power embedded processors),
           please refer include/linux/mmzone.h to modify zone_idex_to_str to
           get the right zone type
     """)
     exit()

 if args.extended_fields:
     bpf_text = EXTENDED + bpf_text
 else:
     bpf_text = NO_EXTENDED + bpf_text

 if args.pid:
     bpf_text = bpf_text.replace("PID_FILTER",
                                 "if (id >> 32 != %s) { return 0; }" % args.pid)
 else:
     bpf_text = bpf_text.replace("PID_FILTER", "")
 if debug or args.ebpf:
     print(bpf_text)
     if args.ebpf:
         exit()

 # load BPF program
 b = BPF(text=bpf_text)
 if args.extended_fields:
     b.attach_kretprobe(event="fragmentation_index",
                        fn_name="trace_fragmentation_index_return")

 stack_traces = b.get_table("stack_traces")
 initial_ts = 0

 def zone_idx_to_str(idx):
     # from include/linux/mmzone.h
     # NOTICE: consider only x86_64 servers
     zone_type = {
             'x86_64':
                     {
                         0: "ZONE_DMA",
                         1: "ZONE_DMA32",
                         2: "ZONE_NORMAL"
                     },
             # Zones in Power server only
             'ppc64le':
                     {
                         0: "ZONE_NORMAL",
                         1: "ZONE_MOVABLE"
                     }
     }

     if idx in zone_type[platform.machine()]:
         return zone_type[platform.machine()][idx]
     else:
         return str(idx)

 def compact_result_to_str(status):
     # from include/trace/evnets/mmflags.h
     # from include/linux/compaction.h
     compact_status = {
         # COMPACT_NOT_SUITABLE_ZONE: For more detailed tracepoint
         # output - internal to compaction
         0: "not_suitable_zone",
         # COMPACT_SKIPPED: compaction didn't start as it was not
         # possible or direct reclaim was more suitable
         1: "skipped",
         # COMPACT_DEFERRED: compaction didn't start as it was
         # deferred due to past failures
         2: "deferred",
         # COMPACT_NOT_SUITABLE_PAGE: For more detailed tracepoint
         # output - internal to compaction
         3: "no_suitable_page",
         # COMPACT_CONTINUE: compaction should continue to another pageblock
         4: "continue",
         # COMPACT_COMPLETE: The full zone was compacted scanned but wasn't
         # successful to compact suitable pages.
         5: "complete",
         # COMPACT_PARTIAL_SKIPPED: direct compaction has scanned part of the
         # zone but wasn't successful to compact suitable pages.
         6: "partial_skipped",
         # COMPACT_CONTENDED: compaction terminated prematurely due to lock
         # contentions
         7: "contended",
         # COMPACT_SUCCESS: direct compaction terminated after concluding
         # that the allocation should now succeed
         8: "success",
     }

     if status in compact_status:
         return compact_status[status]
     else:
         return str(status)

 # header
 if args.timestamp:
     print("%-14s" % ("TIME(s)"), end=" ")
 print("%-14s %-6s %-4s %-12s %-5s %-7s" %
       ("COMM", "PID", "NODE", "ZONE", "ORDER", "MODE"), end=" ")
 if args.extended_fields:
     print("%-8s %-8s %-8s %-8s %-8s" %
           ("FRAGIDX", "MIN", "LOW", "HIGH", "FREE"), end=" ")
 print("%9s %16s" % ("LAT(ms)", "STATUS"))

 # process event
 def print_event(cpu, data, size):
     event = b["events"].event(data)

     global initial_ts

     if not initial_ts:
         initial_ts = event.ts

     if args.timestamp:
         delta = event.ts - initial_ts
         print("%-14.9f" % (float(delta) / 1000000), end=" ")

     print("%-14.14s %-6s %-4s %-12s %-5s %-7s" % (
             event.comm.decode("utf-8", "replace"),
             event.pid,
             event.nid,
             zone_idx_to_str(event.idx),
             event.order,
             "SYNC" if event.sync else "ASYNC"), end=" ")
     if args.extended_fields:
         print("%-8.3f %-8s %-8s %-8s %-8s" % (
             (float(event.fragindex) / 1000),
             event.min, event.low, event.high, event.free
             ), end=" ")
     print("%9.3f %16s" % (
         float(event.delta) / 1000000, compact_result_to_str(event.status)))
     if args.kernel_stack:
         for addr in stack_traces.walk(event.stack_id):
             sym = b.ksym(addr, show_offset=True)
             print("\t%s" % sym)
         print("")

     sys.stdout.flush()

 # loop with callback to print_event
 b["events"].open_perf_buffer(print_event, page_cnt=64)
 start_time = datetime.now()
 while not args.duration or datetime.now() - start_time < args.duration:
     try:
         b.perf_buffer_poll()
     except KeyboardInterrupt:
         exit()
	#!/usr/bin/env python
	# @lint-avoid-python-3-compatibility-imports
	#
	# compactsnoop Trace compact zone and print details including issuing PID.
	# For Linux, uses BCC, eBPF.
	#
	# This uses in-kernel eBPF maps to cache process details (PID and comm) by
	# compact zone begin, as well as a starting timestamp for calculating
	# latency.
	#
	# Copyright (c) 2019 Wenbo Zhang
	# Licensed under the Apache License, Version 2.0 (the "License")
	#
	# 11-NOV-2019 Wenbo Zhang Created this.

	from __future__ import print_function
	from bcc import BPF
	import argparse
	import platform
	from datetime import datetime, timedelta
	import sys

	# arguments
	examples = """examples:
	./compactsnoop # trace all compact stall
	./compactsnoop -T # include timestamps
	./compactsnoop -d 10 # trace for 10 seconds only
	./compactsnoop -K # output kernel stack trace
	./compactsnoop -e # show extended fields
	"""

	parser = argparse.ArgumentParser(
	description="Trace compact zone",
	formatter_class=argparse.RawDescriptionHelpFormatter,
	epilog=examples,
	)
	parser.add_argument("-T", "--timestamp", action="store_true",
	help="include timestamp on output")
	parser.add_argument("-p", "--pid", help="trace this PID only")
	parser.add_argument("-d", "--duration",
	help="total duration of trace in seconds")
	parser.add_argument("-K", "--kernel-stack", action="store_true",
	help="output kernel stack trace")
	parser.add_argument("-e", "--extended_fields", action="store_true",
	help="show system memory state")
	parser.add_argument("--ebpf", action="store_true", help=argparse.SUPPRESS)
	args = parser.parse_args()
	debug = 0
	if args.duration:
	args.duration = timedelta(seconds=int(args.duration))

	NO_EXTENDED = """
	#ifdef EXTNEDED_FIELDS
	#undef EXTNEDED_FIELDS
	#endif
	"""

	EXTENDED = """
	#define EXTNEDED_FIELDS 1
	"""

	bpf_text = """
	#include <uapi/linux/ptrace.h>
	#include <linux/sched.h>
	#include <linux/mmzone.h>
	#include <linux/compaction.h>

	struct val_t {
	int nid;
	int idx;
	int order;
	int sync;
	#ifdef EXTNEDED_FIELDS
	int fragindex;
	int low;
	int min;
	int high;
	int free;
	#endif
	u64 ts; // compaction begin time
	};

	struct data_t {
	u32 pid;
	u32 tid;
	int nid;
	int idx;
	int order;
	u64 delta;
	u64 ts; // compaction end time
	int sync;
	#ifdef EXTNEDED_FIELDS
	int fragindex;
	int low;
	int min;
	int high;
	int free;
	#endif
	int status;
	int stack_id;
	char comm[TASK_COMM_LEN];
	};

	BPF_HASH(start, u64, struct val_t);
	BPF_PERF_OUTPUT(events);
	BPF_STACK_TRACE(stack_traces, 2048);

	#ifdef CONFIG_NUMA
	static inline int zone_to_nid_(struct zone *zone)
	{
	int node;
	bpf_probe_read_kernel(&node, sizeof(node), &zone->node);
	return node;
	}
	#else
	static inline int zone_to_nid_(struct zone *zone)
	{
	return 0;
	}
	#endif

	// #define zone_idx(zone) ((zone) - (zone)->zone_pgdat->node_zones)
	static inline int zone_idx_(struct zone *zone)
	{
	struct pglist_data *zone_pgdat = NULL;
	bpf_probe_read_kernel(&zone_pgdat, sizeof(zone_pgdat), &zone->zone_pgdat);
	return ((u64)zone - (u64)zone_pgdat->node_zones)/sizeof(struct zone);
	}

	#ifdef EXTNEDED_FIELDS
	static inline void get_all_wmark_pages(struct zone zone, struct val_t valp)
	{
	u64 _watermark[NR_WMARK] = {};
	u64 watermark_boost = 0;

	bpf_probe_read_kernel(&_watermark, sizeof(_watermark), &zone->_watermark);
	bpf_probe_read_kernel(&watermark_boost, sizeof(watermark_boost),
	&zone->watermark_boost);
	valp->min = _watermark[WMARK_MIN] + watermark_boost;
	valp->low = _watermark[WMARK_LOW] + watermark_boost;
	valp->high = _watermark[WMARK_HIGH] + watermark_boost;
	bpf_probe_read_kernel(&valp->free, sizeof(valp->free),
	&zone->vm_stat[NR_FREE_PAGES]);
	}
	#endif

	static inline void submit_event(void *ctx, int status)
	{
	struct data_t data = {};
	u64 ts = bpf_ktime_get_ns();
	u64 id = bpf_get_current_pid_tgid();
	struct val_t *valp = start.lookup(&id);
	if (valp == NULL) {
	// missed entry
	return;
	}

	data.delta = ts - valp->ts;
	data.ts = ts / 1000;
	data.pid = id >> 32;
	data.tid = id;
	bpf_get_current_comm(&data.comm, sizeof(data.comm));
	data.nid = valp->nid;
	data.idx = valp->idx;
	data.order = valp->order;
	data.sync = valp->sync;

	#ifdef EXTNEDED_FIELDS
	data.fragindex = valp->fragindex;
	data.min = valp->min;
	data.low = valp->low;
	data.high = valp->high;
	data.free = valp->free;
	#endif

	data.status = status;
	data.stack_id = stack_traces.get_stackid(ctx, 0);

	events.perf_submit(ctx, &data, sizeof(data));

	start.delete(&id);
	}

	#ifdef EXTNEDED_FIELDS
	int trace_fragmentation_index_return(struct pt_regs *ctx)
	{
	struct val_t val = { };
	int ret = PT_REGS_RC(ctx);
	u64 id = bpf_get_current_pid_tgid();
	PID_FILTER
	val.fragindex = ret;
	start.update(&id, &val);
	return 0;
	}
	#endif

	static inline void fill_compact_info(struct val_t *valp,
	struct zone *zone,
	int order)
	{
	valp->nid = zone_to_nid_(zone);
	valp->idx = zone_idx_(zone);
	valp->order = order;
	}

	RAW_TRACEPOINT_PROBE(mm_compaction_suitable)
	{
	// TP_PROTO(struct zone *zone, int order, int ret)
	struct zone zone = (struct zone )ctx->args[0];
	struct val_t val = { };
	int order = (int)ctx->args[1];
	int ret = (int)ctx->args[2];
	u64 id;

	if(ret != COMPACT_CONTINUE)
	return 0;

	id = bpf_get_current_pid_tgid();
	PID_FILTER

	#ifdef EXTNEDED_FIELDS
	struct val_t *valp = start.lookup(&id);
	if (valp == NULL) {
	// missed entry or order <= PAGE_ALLOC_COSTLY_ORDER, eg:
	// manual trigger echo 1 > /proc/sys/vm/compact_memory
	val.fragindex = -1000;
	valp = &val;
	}
	fill_compact_info(valp, zone, order);
	get_all_wmark_pages(zone, valp);
	start.update(&id, valp);
	#else
	fill_compact_info(&val, zone, order);
	start.update(&id, &val);
	#endif

	return 0;
	}

	TRACEPOINT_PROBE(compaction, mm_compaction_begin)
	{
	bool sync = args->sync;

	u64 id = bpf_get_current_pid_tgid();
	struct val_t *valp = start.lookup(&id);
	if (valp == NULL) {
	// missed entry
	return 0;
	}

	valp->ts = bpf_ktime_get_ns();
	valp->sync = sync;
	return 0;
	}

	TRACEPOINT_PROBE(compaction, mm_compaction_end)
	{
	submit_event(args, args->status);
	return 0;
	}
	"""

	if platform.machine() != 'x86_64' and platform.machine() != 'ppc64le':
	print("""
	Currently only support x86_64 and power servers, if you want
	to use it on other platforms(including power embedded processors),
	please refer include/linux/mmzone.h to modify zone_idex_to_str to
	get the right zone type
	""")
	exit()

	if args.extended_fields:
	bpf_text = EXTENDED + bpf_text
	else:
	bpf_text = NO_EXTENDED + bpf_text

	if args.pid:
	bpf_text = bpf_text.replace("PID_FILTER",
	"if (id >> 32 != %s) { return 0; }" % args.pid)
	else:
	bpf_text = bpf_text.replace("PID_FILTER", "")
	if debug or args.ebpf:
	print(bpf_text)
	if args.ebpf:
	exit()

	# load BPF program
	b = BPF(text=bpf_text)
	if args.extended_fields:
	b.attach_kretprobe(event="fragmentation_index",
	fn_name="trace_fragmentation_index_return")

	stack_traces = b.get_table("stack_traces")
	initial_ts = 0

	def zone_idx_to_str(idx):
	# from include/linux/mmzone.h
	# NOTICE: consider only x86_64 servers
	zone_type = {
	'x86_64':
	{
	0: "ZONE_DMA",
	1: "ZONE_DMA32",
	2: "ZONE_NORMAL"
	},
	# Zones in Power server only
	'ppc64le':
	{
	0: "ZONE_NORMAL",
	1: "ZONE_MOVABLE"
	}
	}

	if idx in zone_type[platform.machine()]:
	return zone_type[platform.machine()][idx]
	else:
	return str(idx)

	def compact_result_to_str(status):
	# from include/trace/evnets/mmflags.h
	# from include/linux/compaction.h
	compact_status = {
	# COMPACT_NOT_SUITABLE_ZONE: For more detailed tracepoint
	# output - internal to compaction
	0: "not_suitable_zone",
	# COMPACT_SKIPPED: compaction didn't start as it was not
	# possible or direct reclaim was more suitable
	1: "skipped",
	# COMPACT_DEFERRED: compaction didn't start as it was
	# deferred due to past failures
	2: "deferred",
	# COMPACT_NOT_SUITABLE_PAGE: For more detailed tracepoint
	# output - internal to compaction
	3: "no_suitable_page",
	# COMPACT_CONTINUE: compaction should continue to another pageblock
	4: "continue",
	# COMPACT_COMPLETE: The full zone was compacted scanned but wasn't
	# successful to compact suitable pages.
	5: "complete",
	# COMPACT_PARTIAL_SKIPPED: direct compaction has scanned part of the
	# zone but wasn't successful to compact suitable pages.
	6: "partial_skipped",
	# COMPACT_CONTENDED: compaction terminated prematurely due to lock
	# contentions
	7: "contended",
	# COMPACT_SUCCESS: direct compaction terminated after concluding
	# that the allocation should now succeed
	8: "success",
	}

	if status in compact_status:
	return compact_status[status]
	else:
	return str(status)

	# header
	if args.timestamp:
	print("%-14s" % ("TIME(s)"), end=" ")
	print("%-14s %-6s %-4s %-12s %-5s %-7s" %
	("COMM", "PID", "NODE", "ZONE", "ORDER", "MODE"), end=" ")
	if args.extended_fields:
	print("%-8s %-8s %-8s %-8s %-8s" %
	("FRAGIDX", "MIN", "LOW", "HIGH", "FREE"), end=" ")
	print("%9s %16s" % ("LAT(ms)", "STATUS"))

	# process event
	def print_event(cpu, data, size):
	event = b["events"].event(data)

	global initial_ts

	if not initial_ts:
	initial_ts = event.ts

	if args.timestamp:
	delta = event.ts - initial_ts
	print("%-14.9f" % (float(delta) / 1000000), end=" ")

	print("%-14.14s %-6s %-4s %-12s %-5s %-7s" % (
	event.comm.decode("utf-8", "replace"),
	event.pid,
	event.nid,
	zone_idx_to_str(event.idx),
	event.order,
	"SYNC" if event.sync else "ASYNC"), end=" ")
	if args.extended_fields:
	print("%-8.3f %-8s %-8s %-8s %-8s" % (
	(float(event.fragindex) / 1000),
	event.min, event.low, event.high, event.free
	), end=" ")
	print("%9.3f %16s" % (
	float(event.delta) / 1000000, compact_result_to_str(event.status)))
	if args.kernel_stack:
	for addr in stack_traces.walk(event.stack_id):
	sym = b.ksym(addr, show_offset=True)
	print("\t%s" % sym)
	print("")

	sys.stdout.flush()

	# loop with callback to print_event
	b["events"].open_perf_buffer(print_event, page_cnt=64)
	start_time = datetime.now()
	while not args.duration or datetime.now() - start_time < args.duration:
	try:
	b.perf_buffer_poll()
	except KeyboardInterrupt:
	exit()