From patchwork Tue Jul 3 09:20:58 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Harsh Prateek Bora X-Patchwork-Id: 168743 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 6482F2C0100 for ; Tue, 3 Jul 2012 19:21:50 +1000 (EST) Received: from localhost ([::1]:55524 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SlzIq-0006xk-7T for incoming@patchwork.ozlabs.org; Tue, 03 Jul 2012 05:21:48 -0400 Received: from eggs.gnu.org ([208.118.235.92]:57234) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SlzId-0006xb-4E for qemu-devel@nongnu.org; Tue, 03 Jul 2012 05:21:37 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1SlzIW-000447-3t for qemu-devel@nongnu.org; Tue, 03 Jul 2012 05:21:34 -0400 Received: from e28smtp09.in.ibm.com ([122.248.162.9]:52175) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SlzIU-00041m-TS for qemu-devel@nongnu.org; Tue, 03 Jul 2012 05:21:28 -0400 Received: from /spool/local by e28smtp09.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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X-Received-From: 122.248.162.9 Cc: Harsh Prateek Bora Subject: [Qemu-devel] [PATCH v7 2/3] Simpletrace v2: Support multiple arguments, strings. X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Existing simpletrace backend allows to trace at max 6 args and does not support strings. This newer tracelog format gets rid of fixed size records and therefore allows to trace variable number of args including strings. Sample trace with strings: v9fs_version 0.000 tag=0xffff id=0x64 msize=0x2000 version=9P2000.L v9fs_version_return 6.705 tag=0xffff id=0x64 msize=0x2000 version=9P2000.L Signed-off-by: Harsh Prateek Bora --- scripts/tracetool/backend/simple.py | 84 +++++++++--- trace/simple.c | 256 ++++++++++++++++++++++------------- trace/simple.h | 39 +++++- 3 files changed, 260 insertions(+), 119 deletions(-) diff --git a/scripts/tracetool/backend/simple.py b/scripts/tracetool/backend/simple.py index fbb5717..d3cf4da 100644 --- a/scripts/tracetool/backend/simple.py +++ b/scripts/tracetool/backend/simple.py @@ -15,9 +15,16 @@ __email__ = "stefanha@linux.vnet.ibm.com" from tracetool import out +def is_string(arg): + strtype = ('const char*', 'char*', 'const char *', 'char *') + if arg.lstrip().startswith(strtype): + return True + else: + return False def c(events): out('#include "trace.h"', + '#include "trace/simple.h"', '', 'TraceEvent trace_list[] = {') @@ -26,30 +33,69 @@ def c(events): name = e.name, ) - out('};') - -def h(events): - out('#include "trace/simple.h"', + out('};', '') - for num, e in enumerate(events): - if len(e.args): - argstr = e.args.names() - arg_prefix = ', (uint64_t)(uintptr_t)' - cast_args = arg_prefix + arg_prefix.join(argstr) - simple_args = (str(num) + cast_args) - else: - simple_args = str(num) + for num, event in enumerate(events): + sizes = [] + for type_, name in event.args: + if is_string(type_): + sizes.append("4 + ((" + name + " ? strlen(" + name + ") : 0) % MAX_TRACE_STRLEN)") + else: + sizes.append("8") + sizestr = " + ".join(sizes) + if len(event.args) == 0: + sizestr = '0' - out('static inline void trace_%(name)s(%(args)s)', + out('void trace_%(name)s(%(args)s)', '{', - ' trace%(argc)d(%(trace_args)s);', - '}', - name = e.name, - args = e.args, - argc = len(e.args), - trace_args = simple_args, + ' TraceBufferRecord rec;', + '', + ' if (!trace_list[%(event_id)s].state) {', + ' return;', + ' }', + '', + ' if (trace_record_start(&rec, %(event_id)s, %(size_str)s)) {', + ' return; /* Trace Buffer Full, Event Dropped ! */', + ' }', + name = event.name, + args = event.args, + event_id = num, + size_str = sizestr, ) + if len(event.args) > 0: + for type_, name in event.args: + # string + if is_string(type_): + out(' trace_record_write_str(&rec, %(name)s);', + name = name, + ) + # pointer var (not string) + elif type_.endswith('*'): + out(' trace_record_write_u64(&rec, (uint64_t)(uint64_t *)%(name)s);', + name = name, + ) + # primitive data type + else: + out(' trace_record_write_u64(&rec, (uint64_t)%(name)s);', + name = name, + ) + + out(' trace_record_finish(&rec);', + '}', + '') + + +def h(events): + out('#include "trace/simple.h"', + '') + + for event in events: + out('void trace_%(name)s(%(args)s);', + name = event.name, + args = event.args, + ) + out('') out('#define NR_TRACE_EVENTS %d' % len(events)) out('extern TraceEvent trace_list[NR_TRACE_EVENTS];') diff --git a/trace/simple.c b/trace/simple.c index b64bcf4..3c14568 100644 --- a/trace/simple.c +++ b/trace/simple.c @@ -27,7 +27,7 @@ #define HEADER_MAGIC 0xf2b177cb0aa429b4ULL /** Trace file version number, bump if format changes */ -#define HEADER_VERSION 0 +#define HEADER_VERSION 2 /** Records were dropped event ID */ #define DROPPED_EVENT_ID (~(uint64_t)0 - 1) @@ -35,23 +35,6 @@ /** Trace record is valid */ #define TRACE_RECORD_VALID ((uint64_t)1 << 63) -/** Trace buffer entry */ -typedef struct { - uint64_t event; - uint64_t timestamp_ns; - uint64_t x1; - uint64_t x2; - uint64_t x3; - uint64_t x4; - uint64_t x5; - uint64_t x6; -} TraceRecord; - -enum { - TRACE_BUF_LEN = 4096, - TRACE_BUF_FLUSH_THRESHOLD = TRACE_BUF_LEN / 4, -}; - /* * Trace records are written out by a dedicated thread. The thread waits for * records to become available, writes them out, and then waits again. @@ -62,11 +45,49 @@ static GCond *trace_empty_cond; static bool trace_available; static bool trace_writeout_enabled; -static TraceRecord trace_buf[TRACE_BUF_LEN]; +enum { + TRACE_BUF_LEN = 4096 * 64, + TRACE_BUF_FLUSH_THRESHOLD = TRACE_BUF_LEN / 4, +}; + +uint8_t trace_buf[TRACE_BUF_LEN]; static unsigned int trace_idx; +static unsigned int writeout_idx; +static uint64_t dropped_events; static FILE *trace_fp; static char *trace_file_name = NULL; +/* * Trace buffer entry */ +typedef struct { + uint64_t event; /* TraceEventID */ + uint64_t timestamp_ns; + uint32_t length; /* in bytes */ + uint32_t reserved; /* unused */ + uint8_t arguments[]; +} TraceRecord; + +typedef struct { + uint64_t header_event_id; /* HEADER_EVENT_ID */ + uint64_t header_magic; /* HEADER_MAGIC */ + uint64_t header_version; /* HEADER_VERSION */ +} TraceRecordHeader; + + +static void read_from_buffer(unsigned int idx, void *dataptr, size_t size); +static unsigned int write_to_buffer(unsigned int idx, void *dataptr, size_t size); +static void clear_buffer_range(unsigned int idx, size_t len); + +static void clear_buffer_range(unsigned int idx, size_t len) +{ + uint32_t num = 0; + while (num < len) { + if (idx >= TRACE_BUF_LEN) { + idx = idx % TRACE_BUF_LEN; + } + trace_buf[idx++] = 0; + num++; + } +} /** * Read a trace record from the trace buffer * @@ -75,16 +96,31 @@ static char *trace_file_name = NULL; * * Returns false if the record is not valid. */ -static bool get_trace_record(unsigned int idx, TraceRecord *record) +static bool get_trace_record(unsigned int idx, TraceRecord **recordptr) { - if (!(trace_buf[idx].event & TRACE_RECORD_VALID)) { + uint8_t rec_hdr[sizeof(TraceRecord)]; + uint64_t event_flag = 0; + TraceRecord *record = (TraceRecord *) rec_hdr; + /* read the event flag to see if its a valid record */ + read_from_buffer(idx, rec_hdr, sizeof(event_flag)); + + if (!(record->event & TRACE_RECORD_VALID)) { return false; } __sync_synchronize(); /* read memory barrier before accessing record */ - - *record = trace_buf[idx]; - record->event &= ~TRACE_RECORD_VALID; + /* read the record header to know record length */ + read_from_buffer(idx, rec_hdr, sizeof(TraceRecord)); + *recordptr = g_malloc(record->length); + /* make a copy of record to avoid being overwritten */ + read_from_buffer(idx, (uint8_t *)*recordptr, record->length); + smp_rmb(); /* memory barrier before clearing valid flag */ + (*recordptr)->event &= ~TRACE_RECORD_VALID; + /* clear the trace buffer range for consumed record otherwise any byte + * with its MSB set may be considered as a valid event id when the writer + * thread crosses this range of buffer again. + */ + clear_buffer_range(idx, record->length); return true; } @@ -120,29 +156,41 @@ static void wait_for_trace_records_available(void) static gpointer writeout_thread(gpointer opaque) { - TraceRecord record; - unsigned int writeout_idx = 0; - unsigned int num_available, idx; + TraceRecord *recordptr, *dropped_ptr; + union { + TraceRecord rec; + uint8_t bytes[sizeof(TraceRecord) + sizeof(uint64_t)]; + } dropped; + dropped_ptr = (TraceRecord *)dropped.bytes; + unsigned int idx = 0; + uint64_t dropped_count; size_t unused __attribute__ ((unused)); for (;;) { wait_for_trace_records_available(); - num_available = trace_idx - writeout_idx; - if (num_available > TRACE_BUF_LEN) { - record = (TraceRecord){ - .event = DROPPED_EVENT_ID, - .x1 = num_available, - }; - unused = fwrite(&record, sizeof(record), 1, trace_fp); - writeout_idx += num_available; + if (dropped_events) { + dropped_ptr->event = DROPPED_EVENT_ID, + dropped_ptr->timestamp_ns = get_clock(); + dropped_ptr->length = sizeof(TraceRecord) + sizeof(dropped_events), + dropped_ptr->reserved = 0; + while (1) { + dropped_count = dropped_events; + smp_rmb(); + if (g_atomic_int_compare_and_exchange((gint *)&dropped_events, + dropped_count, 0)) { + break; + } + } + memcpy(dropped_ptr->arguments, &dropped_count, sizeof(uint64_t)); + unused = fwrite(dropped_ptr, dropped_ptr->length, 1, trace_fp); } - idx = writeout_idx % TRACE_BUF_LEN; - while (get_trace_record(idx, &record)) { - trace_buf[idx].event = 0; /* clear valid bit */ - unused = fwrite(&record, sizeof(record), 1, trace_fp); - idx = ++writeout_idx % TRACE_BUF_LEN; + while (get_trace_record(idx, &recordptr)) { + unused = fwrite(recordptr, recordptr->length, 1, trace_fp); + writeout_idx += recordptr->length; + g_free(recordptr); + idx = writeout_idx % TRACE_BUF_LEN; } fflush(trace_fp); @@ -150,73 +198,94 @@ static gpointer writeout_thread(gpointer opaque) return NULL; } -static void trace(TraceEventID event, uint64_t x1, uint64_t x2, uint64_t x3, - uint64_t x4, uint64_t x5, uint64_t x6) +void trace_record_write_u64(TraceBufferRecord *rec, uint64_t val) { - unsigned int idx; - uint64_t timestamp; - - if (!trace_list[event].state) { - return; - } - - timestamp = get_clock(); -#if GLIB_CHECK_VERSION(2, 30, 0) - idx = g_atomic_int_add((gint *)&trace_idx, 1) % TRACE_BUF_LEN; -#else - idx = g_atomic_int_exchange_and_add((gint *)&trace_idx, 1) % TRACE_BUF_LEN; -#endif - trace_buf[idx] = (TraceRecord){ - .event = event, - .timestamp_ns = timestamp, - .x1 = x1, - .x2 = x2, - .x3 = x3, - .x4 = x4, - .x5 = x5, - .x6 = x6, - }; - __sync_synchronize(); /* write barrier before marking as valid */ - trace_buf[idx].event |= TRACE_RECORD_VALID; - - if ((idx + 1) % TRACE_BUF_FLUSH_THRESHOLD == 0) { - flush_trace_file(false); - } + rec->rec_off = write_to_buffer(rec->rec_off, (uint8_t *)&val, sizeof(uint64_t)); } -void trace0(TraceEventID event) +void trace_record_write_str(TraceBufferRecord *rec, const char *s) { - trace(event, 0, 0, 0, 0, 0, 0); + /* Write string length first */ + uint32_t slen = ((s == NULL ? 0 : strlen(s)) % MAX_TRACE_STRLEN); + rec->rec_off = write_to_buffer(rec->rec_off, (uint8_t *)&slen, sizeof(slen)); + /* Write actual string now */ + rec->rec_off = write_to_buffer(rec->rec_off, (uint8_t *)s, slen); } -void trace1(TraceEventID event, uint64_t x1) +int trace_record_start(TraceBufferRecord *rec, TraceEventID event, size_t datasize) { - trace(event, x1, 0, 0, 0, 0, 0); -} + unsigned int idx, rec_off, old_idx, new_idx; + uint32_t rec_len = sizeof(TraceRecord) + datasize; + uint64_t timestamp_ns = get_clock(); + + while (1) { + old_idx = trace_idx; + smp_rmb(); + new_idx = old_idx + rec_len; + + if (new_idx - writeout_idx > TRACE_BUF_LEN) { + /* Trace Buffer Full, Event dropped ! */ + g_atomic_int_inc((gint *)&dropped_events); + return -ENOSPC; + } -void trace2(TraceEventID event, uint64_t x1, uint64_t x2) -{ - trace(event, x1, x2, 0, 0, 0, 0); -} + if (g_atomic_int_compare_and_exchange((gint *)&trace_idx, + old_idx, new_idx)) { + break; + } + } -void trace3(TraceEventID event, uint64_t x1, uint64_t x2, uint64_t x3) -{ - trace(event, x1, x2, x3, 0, 0, 0); + idx = old_idx % TRACE_BUF_LEN; + /* To check later if threshold crossed */ + rec->next_tbuf_idx = new_idx % TRACE_BUF_LEN; + + rec_off = idx; + rec_off = write_to_buffer(rec_off, (uint8_t*)&event, sizeof(event)); + rec_off = write_to_buffer(rec_off, (uint8_t*)×tamp_ns, sizeof(timestamp_ns)); + rec_off = write_to_buffer(rec_off, (uint8_t*)&rec_len, sizeof(rec_len)); + + rec->tbuf_idx = idx; + rec->rec_off = (idx + sizeof(TraceRecord)) % TRACE_BUF_LEN; + return 0; } -void trace4(TraceEventID event, uint64_t x1, uint64_t x2, uint64_t x3, uint64_t x4) +static void read_from_buffer(unsigned int idx, void *dataptr, size_t size) { - trace(event, x1, x2, x3, x4, 0, 0); + uint8_t *data_ptr = dataptr; + uint32_t x = 0; + while (x < size) { + if (idx >= TRACE_BUF_LEN) { + idx = idx % TRACE_BUF_LEN; + } + data_ptr[x++] = trace_buf[idx++]; + } } -void trace5(TraceEventID event, uint64_t x1, uint64_t x2, uint64_t x3, uint64_t x4, uint64_t x5) +static unsigned int write_to_buffer(unsigned int idx, void *dataptr, size_t size) { - trace(event, x1, x2, x3, x4, x5, 0); + uint8_t *data_ptr = dataptr; + uint32_t x = 0; + while (x < size) { + if (idx >= TRACE_BUF_LEN) { + idx = idx % TRACE_BUF_LEN; + } + trace_buf[idx++] = data_ptr[x++]; + } + return idx; /* most callers wants to know where to write next */ } -void trace6(TraceEventID event, uint64_t x1, uint64_t x2, uint64_t x3, uint64_t x4, uint64_t x5, uint64_t x6) +void trace_record_finish(TraceBufferRecord *rec) { - trace(event, x1, x2, x3, x4, x5, x6); + uint8_t temp_rec[sizeof(TraceRecord)]; + TraceRecord *record = (TraceRecord *) temp_rec; + read_from_buffer(rec->tbuf_idx, temp_rec, sizeof(TraceRecord)); + __sync_synchronize(); /* write barrier before marking as valid */ + record->event |= TRACE_RECORD_VALID; + write_to_buffer(rec->tbuf_idx, temp_rec, sizeof(TraceRecord)); + + if ((trace_idx - writeout_idx) > TRACE_BUF_FLUSH_THRESHOLD) { + flush_trace_file(false); + } } void st_set_trace_file_enabled(bool enable) @@ -231,10 +300,11 @@ void st_set_trace_file_enabled(bool enable) flush_trace_file(true); if (enable) { - static const TraceRecord header = { - .event = HEADER_EVENT_ID, - .timestamp_ns = HEADER_MAGIC, - .x1 = HEADER_VERSION, + static const TraceRecordHeader header = { + .header_event_id = HEADER_EVENT_ID, + .header_magic = HEADER_MAGIC, + /* Older log readers will check for version at next location */ + .header_version = HEADER_VERSION, }; trace_fp = fopen(trace_file_name, "wb"); diff --git a/trace/simple.h b/trace/simple.h index 6b5358c..b9818ff 100644 --- a/trace/simple.h +++ b/trace/simple.h @@ -22,16 +22,41 @@ typedef struct { bool state; } TraceEvent; -void trace0(TraceEventID event); -void trace1(TraceEventID event, uint64_t x1); -void trace2(TraceEventID event, uint64_t x1, uint64_t x2); -void trace3(TraceEventID event, uint64_t x1, uint64_t x2, uint64_t x3); -void trace4(TraceEventID event, uint64_t x1, uint64_t x2, uint64_t x3, uint64_t x4); -void trace5(TraceEventID event, uint64_t x1, uint64_t x2, uint64_t x3, uint64_t x4, uint64_t x5); -void trace6(TraceEventID event, uint64_t x1, uint64_t x2, uint64_t x3, uint64_t x4, uint64_t x5, uint64_t x6); void st_print_trace_file_status(FILE *stream, fprintf_function stream_printf); void st_set_trace_file_enabled(bool enable); bool st_set_trace_file(const char *file); void st_flush_trace_buffer(void); +typedef struct { + unsigned int tbuf_idx; + unsigned int next_tbuf_idx; + unsigned int rec_off; +} TraceBufferRecord; + +/* Note for hackers: Make sure MAX_TRACE_LEN < sizeof(uint32_t) */ +#define MAX_TRACE_STRLEN 512 +/** + * Initialize a trace record and claim space for it in the buffer + * + * @arglen number of bytes required for arguments + */ +int trace_record_start(TraceBufferRecord *rec, TraceEventID id, size_t arglen); + +/** + * Append a 64-bit argument to a trace record + */ +void trace_record_write_u64(TraceBufferRecord *rec, uint64_t val); + +/** + * Append a string argument to a trace record + */ +void trace_record_write_str(TraceBufferRecord *rec, const char *s); + +/** + * Mark a trace record completed + * + * Don't append any more arguments to the trace record after calling this. + */ +void trace_record_finish(TraceBufferRecord *rec); + #endif /* TRACE_SIMPLE_H */