[lvm-devel] master - libdm: add precise timestamps support to libdm-stats
Bryn Reeves
bmr at fedoraproject.org
Mon Aug 24 19:04:16 UTC 2015
Gitweb: http://git.fedorahosted.org/git/?p=lvm2.git;a=commitdiff;h=f4262026b671ac2604ec8143c6fe328e9ab159aa
Commit: f4262026b671ac2604ec8143c6fe328e9ab159aa
Parent: 82a27a85b54b68277e79de2fa9b4fadb01330497
Author: Bryn M. Reeves <bmr at redhat.com>
AuthorDate: Thu Aug 20 11:55:06 2015 +0100
Committer: Bryn M. Reeves <bmr at redhat.com>
CommitterDate: Mon Aug 24 20:03:21 2015 +0100
libdm: add precise timestamps support to libdm-stats
Add support for the kernel precise_timestamps feature. This allows
regions to be created using counters with nanosecond precision.
A new dm_stats method, dm_stats_set_precise_timestamps() causes all
future regions created with this handle to attempt to enable precise
counters.
---
WHATS_NEW_DM | 2 +
libdm/.exported_symbols.DM_1_02_106 | 2 +
libdm/libdevmapper.h | 11 +++
libdm/libdm-stats.c | 155 +++++++++++++++++++++++++++++------
tools/dmsetup.c | 1 +
5 files changed, 144 insertions(+), 27 deletions(-)
diff --git a/WHATS_NEW_DM b/WHATS_NEW_DM
index 363f7bf..e083231 100644
--- a/WHATS_NEW_DM
+++ b/WHATS_NEW_DM
@@ -1,5 +1,7 @@
Version 1.02.106 -
===================================
+ Add precise argument to dm_stats_create_region().
+ Add support to libdm-stats for precise_timestamps
Version 1.02.105 - 17th August 2015
===================================
diff --git a/libdm/.exported_symbols.DM_1_02_106 b/libdm/.exported_symbols.DM_1_02_106
index 0ce8924..b664cc6 100644
--- a/libdm/.exported_symbols.DM_1_02_106
+++ b/libdm/.exported_symbols.DM_1_02_106
@@ -1 +1,3 @@
dm_message_supports_precise_timestamps
+dm_stats_create_region
+dm_stats_driver_supports_precise
diff --git a/libdm/libdevmapper.h b/libdm/libdevmapper.h
index 2be2ce3..71b8ce4 100644
--- a/libdm/libdevmapper.h
+++ b/libdm/libdevmapper.h
@@ -473,6 +473,13 @@ int dm_stats_bind_uuid(struct dm_stats *dms, const char *uuid);
*/
int dm_message_supports_precise_timestamps(void);
+/*
+ * Precise timetamps support.
+ *
+ * Test for the presence of precise_timestamps support.
+ */
+int dm_stats_driver_supports_precise(void);
+
#define DM_STATS_ALL_PROGRAMS ""
/*
* Parse the response from a @stats_list message. dm_stats_list will
@@ -535,6 +542,9 @@ int dm_stats_populate(struct dm_stats *dms, const char *program_id,
*
* dm_stats_create_region(dms, 1024, 1 << 11, -2, p, a);
*
+ * If precise is non-zero attempt to create a region with nanosecond
+ * precision counters using the kernel precise_timestamps feature.
+ *
* program_id is an optional string argument that identifies the
* program creating the region. If program_id is NULL or the empty
* string the default program_id stored in the handle will be used.
@@ -548,6 +558,7 @@ int dm_stats_populate(struct dm_stats *dms, const char *program_id,
*/
int dm_stats_create_region(struct dm_stats *dms, uint64_t *region_id,
uint64_t start, uint64_t len, int64_t step,
+ int precise,
const char *program_id, const char *aux_data);
/*
diff --git a/libdm/libdm-stats.c b/libdm/libdm-stats.c
index 4b4135a..b85300f 100644
--- a/libdm/libdm-stats.c
+++ b/libdm/libdm-stats.c
@@ -19,6 +19,8 @@
#define NSEC_PER_MSEC 1000000L
#define NSEC_PER_SEC 1000000000L
+#define PRECISE_ARG "precise_timestamps"
+
/*
* See Documentation/device-mapper/statistics.txt for full descriptions
* of the device-mapper statistics counter fields.
@@ -61,7 +63,8 @@ struct dm_stats {
uint64_t nr_regions; /* total number of present regions */
uint64_t max_region; /* size of the regions table */
uint64_t interval_ns; /* sampling interval in nanoseconds */
- uint64_t timescale; /* sample value multiplier */
+ uint64_t timescale; /* default sample value multiplier */
+ int precise; /* use precise_timestamps when creating regions */
struct dm_stats_region *regions;
/* statistics cursor */
uint64_t cur_region;
@@ -109,8 +112,9 @@ struct dm_stats *dm_stats_create(const char *program_id)
dms->name = NULL;
dms->uuid = NULL;
- /* all regions currently use msec precision */
+ /* by default all regions use msec precision */
dms->timescale = NSEC_PER_MSEC;
+ dms->precise = 0;
dms->nr_regions = DM_STATS_REGION_NOT_PRESENT;
dms->max_region = DM_STATS_REGION_NOT_PRESENT;
@@ -225,6 +229,19 @@ int dm_stats_bind_uuid(struct dm_stats *dms, const char *uuid)
return 1;
}
+static int _stats_check_precise_timestamps(const struct dm_stats *dms)
+{
+ /* Already checked? */
+ if (dms && dms->precise)
+ return 1;
+ return dm_message_supports_precise_timestamps();
+}
+
+int dm_stats_driver_supports_precise(void)
+{
+ return _stats_check_precise_timestamps(NULL);
+}
+
static struct dm_task *_stats_send_message(struct dm_stats *dms, char *msg)
{
struct dm_task *dmt;
@@ -249,24 +266,55 @@ out:
static int _stats_parse_list_region(struct dm_stats_region *region, char *line)
{
- /* FIXME: the kernel imposes no length limit here */
- char program_id[256], aux_data[256];
+ char *p = NULL, string_data[4096]; /* FIXME: add dm_sscanf with %ms? */
+ const char *program_id, *aux_data, *stats_args;
+ const char *empty_string = "";
int r;
- /* line format:
- * <region_id>: <start_sector>+<length> <step> <program_id> <aux_data>
+ memset(string_data, 0, sizeof(string_data));
+
+ /*
+ * Parse fixed fields, line format:
+ *
+ * <region_id>: <start_sector>+<length> <step> <string data>
+ *
+ * Maximum string data size is 4096 - 1 bytes.
*/
- r = sscanf(line, FMTu64 ": " FMTu64 "+" FMTu64 " " FMTu64 "%255s %255s",
- ®ion->region_id, ®ion->start, ®ion->len, ®ion->step,
- program_id, aux_data);
+ r = sscanf(line, FMTu64 ": " FMTu64 "+" FMTu64 " " FMTu64 " %4095c",
+ ®ion->region_id, ®ion->start, ®ion->len,
+ ®ion->step, string_data);
- if (r != 6)
+ if (r != 5)
return_0;
- if (!strcmp(program_id, "-"))
- program_id[0] = '\0';
- if (!strcmp(aux_data, "-"))
- aux_data[0] = '\0';
+ /* program_id is guaranteed to be first. */
+ program_id = string_data;
+
+ /*
+ * FIXME: support embedded '\ ' in string data:
+ * s/strchr/_find_unescaped_space()/
+ */
+ if ((p = strchr(string_data, ' '))) {
+ /* terminate program_id string. */
+ *p = '\0';
+ if (!strcmp(program_id, "-"))
+ program_id = empty_string;
+ aux_data = p + 1;
+ if ((p = strchr(aux_data, ' '))) {
+ /* terminate aux_data string. */
+ *p = '\0';
+ if (!strcmp(aux_data, "-"))
+ aux_data = empty_string;
+ stats_args = p + 1;
+ } else
+ stats_args = empty_string;
+ } else
+ aux_data = stats_args = empty_string;
+
+ if (strstr(stats_args, PRECISE_ARG))
+ region->timescale = 1;
+ else
+ region->timescale = NSEC_PER_MSEC;
if (!(region->program_id = dm_strdup(program_id)))
return_0;
@@ -621,14 +669,17 @@ uint64_t dm_stats_get_nr_areas(const struct dm_stats *dms)
return nr_areas;
}
-int dm_stats_create_region(struct dm_stats *dms, uint64_t *region_id,
- uint64_t start, uint64_t len, int64_t step,
- const char *program_id, const char *aux_data)
+static int _stats_create_region(struct dm_stats *dms, uint64_t *region_id,
+ uint64_t start, uint64_t len, int64_t step,
+ int precise,
+ const char *program_id, const char *aux_data)
{
struct dm_task *dmt = NULL;
char msg[1024], range[64];
const char *err_fmt = "Could not prepare @stats_create %s.";
- const char *resp;
+ const char *precise_str = PRECISE_ARG;
+ const char *resp, *opt_args = NULL;
+ int nr_opt = 0, r = 0; /* number of optional args. */
if (!_stats_bound(dms))
return_0;
@@ -640,16 +691,35 @@ int dm_stats_create_region(struct dm_stats *dms, uint64_t *region_id,
if (!dm_snprintf(range, sizeof(range), FMTu64 "+" FMTu64,
start, len)) {
log_error(err_fmt, "range");
- goto out;
+ return 0;
}
}
- if (!dm_snprintf(msg, sizeof(msg), "@stats_create %s %s" FMTu64 " %s %s",
- (start || len) ? range : "-",
+ if (precise < 0)
+ precise = dms->precise;
+
+ if (precise)
+ nr_opt++;
+ else
+ precise_str = "";
+
+ if (nr_opt) {
+ if ((dm_asprintf((char **)&opt_args, "%d %s", nr_opt,
+ precise_str)) < 0) {
+ log_error(err_fmt, PRECISE_ARG " option.");
+ return 0;
+ }
+ } else
+ opt_args = dm_strdup("");
+
+ if (!dm_snprintf(msg, sizeof(msg), "@stats_create %s %s" FMTu64
+ " %s %s %s", (start || len) ? range : "-",
(step < 0) ? "/" : "",
- (uint64_t)llabs(step), program_id, aux_data)) {
+ (uint64_t)llabs(step),
+ opt_args, program_id, aux_data)) {
log_error(err_fmt, "message");
- goto out;
+ dm_free((void *) opt_args);
+ return 0;
}
if (!(dmt = _stats_send_message(dms, msg)))
@@ -668,14 +738,45 @@ int dm_stats_create_region(struct dm_stats *dms, uint64_t *region_id,
goto_out;
}
- dm_task_destroy(dmt);
+ r = 1;
- return 1;
out:
if(dmt)
dm_task_destroy(dmt);
- return 0;
+ dm_free((void *) opt_args);
+ return r;
+}
+
+int dm_stats_create_region(struct dm_stats *dms, uint64_t *region_id,
+ uint64_t start, uint64_t len, int64_t step,
+ int precise,
+ const char *program_id,
+ const char *aux_data)
+{
+ /* Nanosecond counters need precise_timestamps. */
+ if (precise && !_stats_check_precise_timestamps(dms))
+ return 0;
+
+ return _stats_create_region(dms, region_id, start, len, step,
+ precise,
+ program_id, aux_data);
+}
+
+/* Backward compatible dm_stats_create_region() */
+#if defined(__GNUC__)
+int dm_stats_create_region_v1_02_104(struct dm_stats *dms, uint64_t *region_id,
+ uint64_t start, uint64_t len, int64_t step,
+ const char *program_id, const char *aux_data);
+int dm_stats_create_region_v1_02_104(struct dm_stats *dms, uint64_t *region_id,
+ uint64_t start, uint64_t len, int64_t step,
+ const char *program_id, const char *aux_data)
+{
+ return _stats_create_region(dms, region_id, start, len, step,
+ dms->precise,
+ program_id, aux_data);
}
+DM_EXPORT_SYMBOL(dm_stats_create_region, 1_02_104);
+#endif
int dm_stats_delete_region(struct dm_stats *dms, uint64_t region_id)
{
@@ -815,7 +916,7 @@ static int _dm_stats_populate_region(struct dm_stats *dms, uint64_t region_id,
if (!_stats_bound(dms))
return_0;
- if (!_stats_parse_region(dms->mem, resp, region, dms->timescale)) {
+ if (!_stats_parse_region(dms->mem, resp, region, region->timescale)) {
log_error("Could not parse @stats_print message response.");
return 0;
}
diff --git a/tools/dmsetup.c b/tools/dmsetup.c
index 45d4173..b8376dd 100644
--- a/tools/dmsetup.c
+++ b/tools/dmsetup.c
@@ -4520,6 +4520,7 @@ static int _do_stats_create_regions(struct dm_stats *dms,
this_len = (segments) ? segment_len : this_len;
if (!dm_stats_create_region(dms, ®ion_id,
this_start, this_len, step,
+ -1,
program_id, aux_data)) {
log_error("%s: Could not create statistics region.",
devname);
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