Make perf ring buffer size configurable
As discussed in #966, this PR makes the size of the ring buffer used to send
data to userspace configurable. It changes the Python, Lua and C++ APIs to
expose this knob.
It also defaults the buffer size to a larger value (64 pages per CPU, an 8x
increase) for several tools which produce a lot of output, as well as making it
configurable in `trace` via a `-b` flag.
diff --git a/docs/reference_guide.md b/docs/reference_guide.md
index f976443..9e10a99 100644
--- a/docs/reference_guide.md
+++ b/docs/reference_guide.md
@@ -865,9 +865,9 @@
### 2. open_perf_buffer()
-Syntax: ```table.open_perf_buffers(callback)```
+Syntax: ```table.open_perf_buffers(callback, page_cnt=N)```
-This operates on a table as defined in BPF as BPF_PERF_OUTPUT(), and associates the callback Python function ```callback``` to be called when data is available in the perf ring buffer. This is part of the recommended mechanism for transferring per-event data from kernel to user space.
+This operates on a table as defined in BPF as BPF_PERF_OUTPUT(), and associates the callback Python function ```callback``` to be called when data is available in the perf ring buffer. This is part of the recommended mechanism for transferring per-event data from kernel to user space. The size of the perf ring buffer can be specified via the ```page_cnt``` parameter, which must be a power of two number of pages and defaults to 8.
Example:
diff --git a/examples/lua/bashreadline.lua b/examples/lua/bashreadline.lua
index ebb4c35..045fbc0 100755
--- a/examples/lua/bashreadline.lua
+++ b/examples/lua/bashreadline.lua
@@ -24,7 +24,7 @@
print("%-9s %-6d %s" % {os.date("%H:%M:%S"), tonumber(event.pid), ffi.string(event.str)})
end
- b:get_table("events"):open_perf_buffer(print_readline, "struct { uint64_t pid; char str[80]; }")
+ b:get_table("events"):open_perf_buffer(print_readline, "struct { uint64_t pid; char str[80]; }", nil)
print("%-9s %-6s %s" % {"TIME", "PID", "COMMAND"})
b:kprobe_poll_loop()
diff --git a/src/cc/BPF.cc b/src/cc/BPF.cc
index 9e1c23a..809bfdb 100644
--- a/src/cc/BPF.cc
+++ b/src/cc/BPF.cc
@@ -392,11 +392,14 @@
}
StatusTuple BPF::open_perf_buffer(const std::string& name,
- perf_reader_raw_cb cb, void* cb_cookie) {
+ perf_reader_raw_cb cb, void* cb_cookie,
+ int page_cnt) {
if (perf_buffers_.find(name) == perf_buffers_.end())
perf_buffers_[name] = new BPFPerfBuffer(bpf_module_.get(), name);
+ if ((page_cnt & (page_cnt - 1)) != 0)
+ return StatusTuple(-1, "open_perf_buffer page_cnt must be a power of two");
auto table = perf_buffers_[name];
- TRY2(table->open_all_cpu(cb, cb_cookie));
+ TRY2(table->open_all_cpu(cb, cb_cookie, page_cnt));
return StatusTuple(0);
}
diff --git a/src/cc/BPF.h b/src/cc/BPF.h
index ba2c15b..a4a8817 100644
--- a/src/cc/BPF.h
+++ b/src/cc/BPF.h
@@ -27,6 +27,8 @@
#include "compat/linux/bpf.h"
#include "libbpf.h"
+static const int DEFAULT_PERF_BUFFER_PAGE_CNT = 8;
+
namespace ebpf {
struct open_probe_t {
@@ -96,7 +98,8 @@
}
StatusTuple open_perf_buffer(const std::string& name, perf_reader_raw_cb cb,
- void* cb_cookie = nullptr);
+ void* cb_cookie = nullptr,
+ int page_cnt = DEFAULT_PERF_BUFFER_PAGE_CNT);
StatusTuple close_perf_buffer(const std::string& name);
void poll_perf_buffer(const std::string& name, int timeout = -1);
diff --git a/src/cc/BPFTable.cc b/src/cc/BPFTable.cc
index 837d5bd..d0f2b99 100644
--- a/src/cc/BPFTable.cc
+++ b/src/cc/BPFTable.cc
@@ -67,11 +67,11 @@
}
StatusTuple BPFPerfBuffer::open_on_cpu(perf_reader_raw_cb cb, int cpu,
- void* cb_cookie) {
+ void* cb_cookie, int page_cnt) {
if (cpu_readers_.find(cpu) != cpu_readers_.end())
return StatusTuple(-1, "Perf buffer already open on CPU %d", cpu);
auto reader =
- static_cast<perf_reader*>(bpf_open_perf_buffer(cb, cb_cookie, -1, cpu));
+ static_cast<perf_reader*>(bpf_open_perf_buffer(cb, cb_cookie, -1, cpu, page_cnt));
if (reader == nullptr)
return StatusTuple(-1, "Unable to construct perf reader");
int reader_fd = perf_reader_fd(reader);
@@ -86,12 +86,12 @@
}
StatusTuple BPFPerfBuffer::open_all_cpu(perf_reader_raw_cb cb,
- void* cb_cookie) {
+ void* cb_cookie, int page_cnt) {
if (cpu_readers_.size() != 0 || readers_.size() != 0)
return StatusTuple(-1, "Previously opened perf buffer not cleaned");
for (int i: get_online_cpus()) {
- auto res = open_on_cpu(cb, i, cb_cookie);
+ auto res = open_on_cpu(cb, i, cb_cookie, page_cnt);
if (res.code() != 0) {
TRY2(close_all_cpu());
return res;
diff --git a/src/cc/BPFTable.h b/src/cc/BPFTable.h
index c5f805d..98424f1 100644
--- a/src/cc/BPFTable.h
+++ b/src/cc/BPFTable.h
@@ -126,12 +126,14 @@
: BPFTableBase<int, int>(bpf_module, name) {}
~BPFPerfBuffer();
- StatusTuple open_all_cpu(perf_reader_raw_cb cb, void* cb_cookie);
+ StatusTuple open_all_cpu(perf_reader_raw_cb cb, void* cb_cookie,
+ int page_cnt);
StatusTuple close_all_cpu();
void poll(int timeout);
private:
- StatusTuple open_on_cpu(perf_reader_raw_cb cb, int cpu, void* cb_cookie);
+ StatusTuple open_on_cpu(perf_reader_raw_cb cb, int cpu, void* cb_cookie,
+ int page_cnt);
StatusTuple close_on_cpu(int cpu);
std::map<int, perf_reader*> cpu_readers_;
diff --git a/src/cc/libbpf.c b/src/cc/libbpf.c
index f3d2881..864b89e 100644
--- a/src/cc/libbpf.c
+++ b/src/cc/libbpf.c
@@ -65,6 +65,8 @@
#define PERF_FLAG_FD_CLOEXEC (1UL << 3)
#endif
+static int probe_perf_reader_page_cnt = 8;
+
static __u64 ptr_to_u64(void *ptr)
{
return (__u64) (unsigned long) ptr;
@@ -351,7 +353,7 @@
int n;
snprintf(new_name, sizeof(new_name), "%s_bcc_%d", ev_name, getpid());
- reader = perf_reader_new(cb, NULL, cb_cookie);
+ reader = perf_reader_new(cb, NULL, cb_cookie, probe_perf_reader_page_cnt);
if (!reader)
goto error;
@@ -411,7 +413,7 @@
int n;
snprintf(new_name, sizeof(new_name), "%s_bcc_%d", ev_name, getpid());
- reader = perf_reader_new(cb, NULL, cb_cookie);
+ reader = perf_reader_new(cb, NULL, cb_cookie, probe_perf_reader_page_cnt);
if (!reader)
goto error;
@@ -493,7 +495,7 @@
char buf[256];
struct perf_reader *reader = NULL;
- reader = perf_reader_new(cb, NULL, cb_cookie);
+ reader = perf_reader_new(cb, NULL, cb_cookie, probe_perf_reader_page_cnt);
if (!reader)
goto error;
@@ -515,12 +517,13 @@
return 0;
}
-void * bpf_open_perf_buffer(perf_reader_raw_cb raw_cb, void *cb_cookie, int pid, int cpu) {
+void * bpf_open_perf_buffer(perf_reader_raw_cb raw_cb, void *cb_cookie, int pid,
+ int cpu, int page_cnt) {
int pfd;
struct perf_event_attr attr = {};
struct perf_reader *reader = NULL;
- reader = perf_reader_new(NULL, raw_cb, cb_cookie);
+ reader = perf_reader_new(NULL, raw_cb, cb_cookie, page_cnt);
if (!reader)
goto error;
diff --git a/src/cc/libbpf.h b/src/cc/libbpf.h
index 07afaa9..0e9fda2 100644
--- a/src/cc/libbpf.h
+++ b/src/cc/libbpf.h
@@ -68,7 +68,8 @@
int group_fd, perf_reader_cb cb, void *cb_cookie);
int bpf_detach_tracepoint(const char *tp_category, const char *tp_name);
-void * bpf_open_perf_buffer(perf_reader_raw_cb raw_cb, void *cb_cookie, int pid, int cpu);
+void * bpf_open_perf_buffer(perf_reader_raw_cb raw_cb, void *cb_cookie, int pid,
+ int cpu, int page_cnt);
/* attached a prog expressed by progfd to the device specified in dev_name */
int bpf_attach_xdp(const char *dev_name, int progfd);
diff --git a/src/cc/perf_reader.c b/src/cc/perf_reader.c
index 793a069..a9ed18e 100644
--- a/src/cc/perf_reader.c
+++ b/src/cc/perf_reader.c
@@ -26,8 +26,6 @@
#include "libbpf.h"
#include "perf_reader.h"
-int perf_reader_page_cnt = 8;
-
struct perf_reader {
perf_reader_cb cb;
perf_reader_raw_cb raw_cb;
@@ -42,7 +40,8 @@
uint64_t sample_type;
};
-struct perf_reader * perf_reader_new(perf_reader_cb cb, perf_reader_raw_cb raw_cb, void *cb_cookie) {
+struct perf_reader * perf_reader_new(perf_reader_cb cb,
+ perf_reader_raw_cb raw_cb, void *cb_cookie, int page_cnt) {
struct perf_reader *reader = calloc(1, sizeof(struct perf_reader));
if (!reader)
return NULL;
@@ -51,7 +50,7 @@
reader->cb_cookie = cb_cookie;
reader->fd = -1;
reader->page_size = getpagesize();
- reader->page_cnt = perf_reader_page_cnt;
+ reader->page_cnt = page_cnt;
return reader;
}
diff --git a/src/cc/perf_reader.h b/src/cc/perf_reader.h
index 6376c47..4bbb1e3 100644
--- a/src/cc/perf_reader.h
+++ b/src/cc/perf_reader.h
@@ -25,7 +25,8 @@
struct perf_reader;
-struct perf_reader * perf_reader_new(perf_reader_cb cb, perf_reader_raw_cb raw_cb, void *cb_cookie);
+struct perf_reader * perf_reader_new(perf_reader_cb cb,
+ perf_reader_raw_cb raw_cb, void *cb_cookie, int page_cnt);
void perf_reader_free(void *ptr);
int perf_reader_mmap(struct perf_reader *reader, unsigned type, unsigned long sample_type);
int perf_reader_poll(int num_readers, struct perf_reader **readers, int timeout);
diff --git a/src/lua/bcc/libbcc.lua b/src/lua/bcc/libbcc.lua
index 762db9c..fa28e21 100644
--- a/src/lua/bcc/libbcc.lua
+++ b/src/lua/bcc/libbcc.lua
@@ -54,7 +54,7 @@
int bpf_detach_uprobe(const char *ev_name);
-void * bpf_open_perf_buffer(perf_reader_raw_cb raw_cb, void *cb_cookie, int pid, int cpu);
+void * bpf_open_perf_buffer(perf_reader_raw_cb raw_cb, void *cb_cookie, int pid, int cpu, int page_cnt);
]]
ffi.cdef[[
diff --git a/src/lua/bcc/table.lua b/src/lua/bcc/table.lua
index c01f006..3144f22 100644
--- a/src/lua/bcc/table.lua
+++ b/src/lua/bcc/table.lua
@@ -243,13 +243,14 @@
return string.format("bcc:perf_event_array:%d:%d", tonumber(id), cpu or 0)
end
-function PerfEventArray:_open_perf_buffer(cpu, callback, ctype)
+function PerfEventArray:_open_perf_buffer(cpu, callback, ctype, page_cnt)
local _cb = ffi.cast("perf_reader_raw_cb",
function (cookie, data, size)
callback(cpu, ctype(data)[0])
end)
- local reader = libbcc.bpf_open_perf_buffer(_cb, nil, -1, cpu)
+ -- default to 8 pages per buffer
+ local reader = libbcc.bpf_open_perf_buffer(_cb, nil, -1, cpu, page_cnt or 8)
assert(reader, "failed to open perf buffer")
local fd = libbcc.perf_reader_fd(reader)
@@ -258,11 +259,11 @@
self._callbacks[cpu] = _cb
end
-function PerfEventArray:open_perf_buffer(callback, data_type, ...)
+function PerfEventArray:open_perf_buffer(callback, data_type, data_params, page_cnt)
assert(data_type, "a data type is needed for callback conversion")
- local ctype = ffi.typeof(data_type.."*", ...)
+ local ctype = ffi.typeof(data_type.."*", unpack(data_params or {}))
for i = 0, Posix.cpu_count() - 1 do
- self:_open_perf_buffer(i, callback, ctype)
+ self:_open_perf_buffer(i, callback, ctype, page_cnt)
end
end
diff --git a/src/python/bcc/libbcc.py b/src/python/bcc/libbcc.py
index 9db1550..099af8f 100644
--- a/src/python/bcc/libbcc.py
+++ b/src/python/bcc/libbcc.py
@@ -102,7 +102,7 @@
lib.bpf_detach_tracepoint.restype = ct.c_int
lib.bpf_detach_tracepoint.argtypes = [ct.c_char_p, ct.c_char_p]
lib.bpf_open_perf_buffer.restype = ct.c_void_p
-lib.bpf_open_perf_buffer.argtypes = [_RAW_CB_TYPE, ct.py_object, ct.c_int, ct.c_int]
+lib.bpf_open_perf_buffer.argtypes = [_RAW_CB_TYPE, ct.py_object, ct.c_int, ct.c_int, ct.c_int]
lib.bpf_open_perf_event.restype = ct.c_int
lib.bpf_open_perf_event.argtypes = [ct.c_uint, ct.c_ulonglong, ct.c_int, ct.c_int]
lib.perf_reader_poll.restype = ct.c_int
diff --git a/src/python/bcc/table.py b/src/python/bcc/table.py
index bb4cd41..18851f2 100644
--- a/src/python/bcc/table.py
+++ b/src/python/bcc/table.py
@@ -507,20 +507,25 @@
super(PerfEventArray, self).__delitem__(key)
self.close_perf_buffer(key)
- def open_perf_buffer(self, callback):
+ def open_perf_buffer(self, callback, page_cnt=8):
"""open_perf_buffers(callback)
Opens a set of per-cpu ring buffer to receive custom perf event
data from the bpf program. The callback will be invoked for each
- event submitted from the kernel, up to millions per second.
+ event submitted from the kernel, up to millions per second. Use
+ page_cnt to change the size of the per-cpu ring buffer. The value
+ must be a power of two and defaults to 8.
"""
- for i in get_online_cpus():
- self._open_perf_buffer(i, callback)
+ if page_cnt & (page_cnt - 1) != 0:
+ raise Exception("Perf buffer page_cnt must be a power of two")
- def _open_perf_buffer(self, cpu, callback):
+ for i in get_online_cpus():
+ self._open_perf_buffer(i, callback, page_cnt)
+
+ def _open_perf_buffer(self, cpu, callback, page_cnt):
fn = _RAW_CB_TYPE(lambda _, data, size: callback(cpu, data, size))
- reader = lib.bpf_open_perf_buffer(fn, None, -1, cpu)
+ reader = lib.bpf_open_perf_buffer(fn, None, -1, cpu, page_cnt)
if not reader:
raise Exception("Could not open perf buffer")
fd = lib.perf_reader_fd(reader)
diff --git a/tools/biosnoop.lua b/tools/biosnoop.lua
index ac08897..fac7f3b 100644
--- a/tools/biosnoop.lua
+++ b/tools/biosnoop.lua
@@ -175,9 +175,9 @@
uint64_t sector;
uint64_t len;
uint64_t ts;
- char disk_name[%d];
- char name[%d];
+ char disk_name[$];
+ char name[$];
}
- ]] % {DISK_NAME_LEN, TASK_COMM_LEN})
+ ]], {DISK_NAME_LEN, TASK_COMM_LEN}, 64)
bpf:kprobe_poll_loop()
end
diff --git a/tools/biosnoop.py b/tools/biosnoop.py
index aa8a077..3d77e52 100755
--- a/tools/biosnoop.py
+++ b/tools/biosnoop.py
@@ -182,6 +182,6 @@
start_ts = 1
# loop with callback to print_event
-b["events"].open_perf_buffer(print_event)
+b["events"].open_perf_buffer(print_event, page_cnt=64)
while 1:
b.kprobe_poll()
diff --git a/tools/btrfsslower.py b/tools/btrfsslower.py
index fcc155e..8b34900 100755
--- a/tools/btrfsslower.py
+++ b/tools/btrfsslower.py
@@ -343,6 +343,6 @@
"BYTES", "OFF_KB", "LAT(ms)", "FILENAME"))
# read events
-b["events"].open_perf_buffer(print_event)
+b["events"].open_perf_buffer(print_event, page_cnt=64)
while 1:
b.kprobe_poll()
diff --git a/tools/cpuunclaimed.py b/tools/cpuunclaimed.py
index 9624b50..3998f9f 100755
--- a/tools/cpuunclaimed.py
+++ b/tools/cpuunclaimed.py
@@ -205,7 +205,7 @@
trigger = int(0.8 * (1000000000 / frequency))
# read events
-b["events"].open_perf_buffer(print_event)
+b["events"].open_perf_buffer(print_event, page_cnt=64)
while 1:
# allow some buffering by calling sleep(), to reduce the context switch
# rate and lower overhead.
diff --git a/tools/dbslower.py b/tools/dbslower.py
index 70e0503..6ddec41 100755
--- a/tools/dbslower.py
+++ b/tools/dbslower.py
@@ -131,7 +131,7 @@
(', '.join(map(str, args.pids)), args.threshold))
print("%-14s %-6s %8s %s" % ("TIME(s)", "PID", "MS", "QUERY"))
-bpf["events"].open_perf_buffer(print_event)
+bpf["events"].open_perf_buffer(print_event, page_cnt=64)
while True:
bpf.kprobe_poll()
diff --git a/tools/dcsnoop.py b/tools/dcsnoop.py
index d162a66..a72ba41 100755
--- a/tools/dcsnoop.py
+++ b/tools/dcsnoop.py
@@ -153,6 +153,6 @@
# header
print("%-11s %-6s %-16s %1s %s" % ("TIME(s)", "PID", "COMM", "T", "FILE"))
-b["events"].open_perf_buffer(print_event)
+b["events"].open_perf_buffer(print_event, page_cnt=64)
while 1:
b.kprobe_poll()
diff --git a/tools/ext4slower.py b/tools/ext4slower.py
index 20865a5..4950325 100755
--- a/tools/ext4slower.py
+++ b/tools/ext4slower.py
@@ -337,6 +337,6 @@
"BYTES", "OFF_KB", "LAT(ms)", "FILENAME"))
# read events
-b["events"].open_perf_buffer(print_event)
+b["events"].open_perf_buffer(print_event, page_cnt=64)
while 1:
b.kprobe_poll()
diff --git a/tools/fileslower.py b/tools/fileslower.py
index 2ae4756..ab29990 100755
--- a/tools/fileslower.py
+++ b/tools/fileslower.py
@@ -243,6 +243,6 @@
time.time() - start_ts, event.comm, event.pid, mode_s[event.mode],
event.sz, ms, name))
-b["events"].open_perf_buffer(print_event)
+b["events"].open_perf_buffer(print_event, page_cnt=64)
while 1:
b.kprobe_poll()
diff --git a/tools/mysqld_qslower.py b/tools/mysqld_qslower.py
index 94906a8..3ed18ec 100755
--- a/tools/mysqld_qslower.py
+++ b/tools/mysqld_qslower.py
@@ -128,6 +128,6 @@
event.pid, float(event.delta) / 1000000, event.query))
# loop with callback to print_event
-b["events"].open_perf_buffer(print_event)
+b["events"].open_perf_buffer(print_event, page_cnt=64)
while 1:
b.kprobe_poll()
diff --git a/tools/opensnoop.py b/tools/opensnoop.py
index 0c2b9b5..dae4ff4 100755
--- a/tools/opensnoop.py
+++ b/tools/opensnoop.py
@@ -178,6 +178,6 @@
event.comm, fd_s, err, event.fname))
# loop with callback to print_event
-b["events"].open_perf_buffer(print_event)
+b["events"].open_perf_buffer(print_event, page_cnt=64)
while 1:
b.kprobe_poll()
diff --git a/tools/stacksnoop.lua b/tools/stacksnoop.lua
index 8f5f5b4..7dfaf3d 100755
--- a/tools/stacksnoop.lua
+++ b/tools/stacksnoop.lua
@@ -102,6 +102,6 @@
bpf:get_table("events"):open_perf_buffer(print_event,
"struct { uint64_t stack_id; uint32_t pid; char comm[$]; }",
- TASK_COMM_LEN)
+ {TASK_COMM_LEN})
bpf:kprobe_poll_loop()
end
diff --git a/tools/statsnoop.py b/tools/statsnoop.py
index 2fc2164..d9164b6 100755
--- a/tools/statsnoop.py
+++ b/tools/statsnoop.py
@@ -159,6 +159,6 @@
fd_s, err, event.fname))
# loop with callback to print_event
-b["events"].open_perf_buffer(print_event)
+b["events"].open_perf_buffer(print_event, page_cnt=64)
while 1:
b.kprobe_poll()
diff --git a/tools/tcplife.py b/tools/tcplife.py
index 1125f9c..69ba174 100755
--- a/tools/tcplife.py
+++ b/tools/tcplife.py
@@ -354,7 +354,7 @@
start_ts = 0
# read events
-b["ipv4_events"].open_perf_buffer(print_ipv4_event)
-b["ipv6_events"].open_perf_buffer(print_ipv6_event)
+b["ipv4_events"].open_perf_buffer(print_ipv4_event, page_cnt=64)
+b["ipv6_events"].open_perf_buffer(print_ipv6_event, page_cnt=64)
while 1:
b.kprobe_poll()
diff --git a/tools/trace.py b/tools/trace.py
index 46bc97e..029194c 100755
--- a/tools/trace.py
+++ b/tools/trace.py
@@ -29,6 +29,7 @@
use_localtime = True
tgid = -1
pid = -1
+ page_cnt = None
@classmethod
def configure(cls, args):
@@ -38,6 +39,7 @@
cls.first_ts = BPF.monotonic_time()
cls.tgid = args.tgid or -1
cls.pid = args.pid or -1
+ cls.page_cnt = args.buffer_pages
def __init__(self, probe, string_size, kernel_stack, user_stack):
self.usdt = None
@@ -510,7 +512,8 @@
self._attach_u(bpf)
self.python_struct = self._generate_python_data_decl()
callback = partial(self.print_event, bpf)
- bpf[self.events_name].open_perf_buffer(callback)
+ bpf[self.events_name].open_perf_buffer(callback,
+ page_cnt=self.page_cnt)
def _attach_k(self, bpf):
if self.probe_type == "r":
@@ -543,6 +546,7 @@
pid=Probe.tgid)
class Tool(object):
+ DEFAULT_PERF_BUFFER_PAGES = 64
examples = """
EXAMPLES:
@@ -577,6 +581,10 @@
"functions and print trace messages.",
formatter_class=argparse.RawDescriptionHelpFormatter,
epilog=Tool.examples)
+ parser.add_argument("-b", "--buffer-pages", type=int,
+ default=Tool.DEFAULT_PERF_BUFFER_PAGES,
+ help="number of pages to use for perf_events ring buffer "
+ "(default: %(default)d)")
# we'll refer to the userspace concepts of "pid" and "tid" by
# their kernel names -- tgid and pid -- inside the script
parser.add_argument("-p", "--pid", type=int, metavar="PID",
diff --git a/tools/trace_example.txt b/tools/trace_example.txt
index 504030c..eb72e5e 100644
--- a/tools/trace_example.txt
+++ b/tools/trace_example.txt
@@ -201,11 +201,28 @@
libraries and then accessing the /home/vagrant directory listing.
+Lastly, if a high-frequency event is traced you may overflow the perf ring
+buffer. This shows as "Lost N samples":
+
+# trace sys_open
+5087 5087 pgrep sys_open
+5087 5087 pgrep sys_open
+5087 5087 pgrep sys_open
+5087 5087 pgrep sys_open
+5087 5087 pgrep sys_open
+Lost 764896 samples
+Lost 764896 samples
+Lost 764896 samples
+
+The perf ring buffer size can be changed with -b. The unit is size per-CPU buffer
+size and is measured in pages. The value must be a power of two and defaults to
+64 pages.
+
+
USAGE message:
-# trace -h
-usage: trace [-h] [-p PID] [-L TID] [-v] [-Z STRING_SIZE] [-S]
- [-M MAX_EVENTS] [-t] [-T] [-K] [-U] [-I header]
+usage: trace [-h] [-b BUFFER_PAGES] [-p PID] [-L TID] [-v] [-Z STRING_SIZE]
+ [-S] [-M MAX_EVENTS] [-t] [-T] [-K] [-U] [-I header]
probe [probe ...]
Attach to functions and print trace messages.
@@ -215,6 +232,9 @@
optional arguments:
-h, --help show this help message and exit
+ -b BUFFER_PAGES, --buffer-pages BUFFER_PAGES
+ number of pages to use for perf_events ring buffer
+ (default: 64)
-p PID, --pid PID id of the process to trace (optional)
-L TID, --tid TID id of the thread to trace (optional)
-v, --verbose print resulting BPF program code before executing
@@ -224,7 +244,7 @@
-M MAX_EVENTS, --max-events MAX_EVENTS
number of events to print before quitting
-t, --timestamp print timestamp column (offset from trace start)
- -T, --time print time column
+ -T, --time print time column
-K, --kernel-stack output kernel stack trace
-U, --user-stack output user stack trace
-I header, --include header
@@ -247,9 +267,9 @@
Trace malloc calls and print the size being allocated
trace 'p:c:write (arg1 == 1) "writing %d bytes to STDOUT", arg3'
Trace the write() call from libc to monitor writes to STDOUT
-trace 'r::__kmalloc (retval == 0) "kmalloc failed!"
+trace 'r::__kmalloc (retval == 0) "kmalloc failed!"'
Trace returns from __kmalloc which returned a null pointer
-trace 'r:c:malloc (retval) "allocated = %x", retval
+trace 'r:c:malloc (retval) "allocated = %x", retval'
Trace returns from malloc and print non-NULL allocated buffers
trace 't:block:block_rq_complete "sectors=%d", args->nr_sector'
Trace the block_rq_complete kernel tracepoint and print # of tx sectors
diff --git a/tools/xfsslower.py b/tools/xfsslower.py
index 25c5a20..3fbc96d 100755
--- a/tools/xfsslower.py
+++ b/tools/xfsslower.py
@@ -293,6 +293,6 @@
"BYTES", "OFF_KB", "LAT(ms)", "FILENAME"))
# read events
-b["events"].open_perf_buffer(print_event)
+b["events"].open_perf_buffer(print_event, page_cnt=64)
while 1:
b.kprobe_poll()
diff --git a/tools/zfsslower.py b/tools/zfsslower.py
index e2be684..f5e8cbb 100755
--- a/tools/zfsslower.py
+++ b/tools/zfsslower.py
@@ -297,6 +297,6 @@
"BYTES", "OFF_KB", "LAT(ms)", "FILENAME"))
# read events
-b["events"].open_perf_buffer(print_event)
+b["events"].open_perf_buffer(print_event, page_cnt=64)
while 1:
b.kprobe_poll()