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hostinfo: reuse proc FD and memory when parsing

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Re-opening the FD on every poll is pretty expensive. So we should avoid
doing that as well re-use the read buffer (page-aligned, <=1 page) for
the sample data.
This commit is contained in:
Christian Hergert
2018-06-16 19:50:44 -07:00
parent a1e3d06296
commit 9665cebbdc
1 changed files with 99 additions and 59 deletions
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158
lib/sources/sp-hostinfo-source.c
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@ -17,20 +17,27 @@
*/
#include <ctype.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <unistd.h>
#include "sources/sp-hostinfo-source.h"
#define PROC_STAT_BUF_SIZE 4096
struct _SpHostinfoSource
{
GObject parent_instance;
guint handler;
gint n_cpu;
gint stat_fd;
SpCaptureWriter *writer;
GArray *cpu_info;
gchar *stat_buf;
};
typedef struct
@ -61,6 +68,30 @@ sp_hostinfo_source_new (void)
return g_object_new (SP_TYPE_HOSTINFO_SOURCE, NULL);
}
static gboolean
read_stat (SpHostinfoSource *self)
{
gssize len;
g_assert (self != NULL);
g_assert (self->stat_fd != -1);
g_assert (self->stat_buf != NULL);
if (lseek (self->stat_fd, 0, SEEK_SET) != 0)
return FALSE;
len = read (self->stat_fd, self->stat_buf, PROC_STAT_BUF_SIZE);
if (len <= 0)
return FALSE;
if (len < PROC_STAT_BUF_SIZE)
self->stat_buf[len] = 0;
else
self->stat_buf[PROC_STAT_BUF_SIZE-1] = 0;
return TRUE;
}
static void
poll_cpu (SpHostinfoSource *self)
{
@ -85,77 +116,78 @@ poll_cpu (SpHostinfoSource *self)
glong steal_calc;
glong guest_calc;
glong guest_nice_calc;
gchar *buf = NULL;
glong total;
gchar *line;
gint ret;
gint id;
gint i;
if (g_file_get_contents("/proc/stat", &buf, NULL, NULL))
if (read_stat (self))
{
line = buf;
for (i = 0; buf[i]; i++)
line = self->stat_buf;
for (gsize i = 0; self->stat_buf[i]; i++)
{
if (buf[i] == '\n') {
buf[i] = '\0';
if (g_str_has_prefix(line, "cpu"))
{
if (isdigit(line[3]))
{
CpuInfo *cpu_info;
if (self->stat_buf[i] == '\n')
{
self->stat_buf[i] = '\0';
user = nice = sys = idle = id = 0;
ret = sscanf (line, "%s %ld %ld %ld %ld %ld %ld %ld %ld %ld %ld",
cpu, &user, &nice, &sys, &idle,
&iowait, &irq, &softirq, &steal, &guest, &guest_nice);
if (ret != 11)
goto next;
if (strncmp (line, "cpu", 3) == 0)
{
if (isdigit (line[3]))
{
CpuInfo *cpu_info;
ret = sscanf(cpu, "cpu%d", &id);
user = nice = sys = idle = id = 0;
ret = sscanf (line, "%s %ld %ld %ld %ld %ld %ld %ld %ld %ld %ld",
cpu, &user, &nice, &sys, &idle,
&iowait, &irq, &softirq, &steal, &guest, &guest_nice);
if (ret != 11)
goto next;
if (ret != 1 || id < 0 || id >= self->n_cpu)
goto next;
ret = sscanf(cpu, "cpu%d", &id);
cpu_info = &g_array_index (self->cpu_info, CpuInfo, id);
if (ret != 1 || id < 0 || id >= self->n_cpu)
goto next;
user_calc = user - cpu_info->last_user;
nice_calc = nice - cpu_info->last_nice;
system_calc = sys - cpu_info->last_system;
idle_calc = idle - cpu_info->last_idle;
iowait_calc = iowait - cpu_info->last_iowait;
irq_calc = irq - cpu_info->last_irq;
softirq_calc = softirq - cpu_info->last_softirq;
steal_calc = steal - cpu_info->last_steal;
guest_calc = guest - cpu_info->last_guest;
guest_nice_calc = guest_nice - cpu_info->last_guest_nice;
cpu_info = &g_array_index (self->cpu_info, CpuInfo, id);
total = user_calc + nice_calc + system_calc + idle_calc + iowait_calc + irq_calc + softirq_calc + steal_calc + guest_calc + guest_nice_calc;
cpu_info->total = ((total - idle_calc) / (gdouble)total) * 100.0;
user_calc = user - cpu_info->last_user;
nice_calc = nice - cpu_info->last_nice;
system_calc = sys - cpu_info->last_system;
idle_calc = idle - cpu_info->last_idle;
iowait_calc = iowait - cpu_info->last_iowait;
irq_calc = irq - cpu_info->last_irq;
softirq_calc = softirq - cpu_info->last_softirq;
steal_calc = steal - cpu_info->last_steal;
guest_calc = guest - cpu_info->last_guest;
guest_nice_calc = guest_nice - cpu_info->last_guest_nice;
cpu_info->last_user = user;
cpu_info->last_nice = nice;
cpu_info->last_idle = idle;
cpu_info->last_system = sys;
cpu_info->last_iowait = iowait;
cpu_info->last_irq = irq;
cpu_info->last_softirq = softirq;
cpu_info->last_steal = steal;
cpu_info->last_guest = guest;
cpu_info->last_guest_nice = guest_nice;
}
} else {
/* CPU info comes first. Skip further lines. */
break;
}
total = user_calc + nice_calc + system_calc + idle_calc + iowait_calc + irq_calc + softirq_calc + steal_calc + guest_calc + guest_nice_calc;
cpu_info->total = ((total - idle_calc) / (gdouble)total) * 100.0;
next:
line = &buf[i + 1];
}
}
}
cpu_info->last_user = user;
cpu_info->last_nice = nice;
cpu_info->last_idle = idle;
cpu_info->last_system = sys;
cpu_info->last_iowait = iowait;
cpu_info->last_irq = irq;
cpu_info->last_softirq = softirq;
cpu_info->last_steal = steal;
cpu_info->last_guest = guest;
cpu_info->last_guest_nice = guest_nice;
}
}
else
{
/* CPU info comes first. Skip further lines. */
break;
}
g_free (buf);
next:
line = &self->stat_buf[i + 1];
}
}
}
}
static void
@ -163,12 +195,11 @@ publish_cpu (SpHostinfoSource *self)
{
SpCaptureCounterValue *counter_values;
guint *counter_ids;
gint i;
counter_ids = alloca (sizeof *counter_ids * self->n_cpu * 2);
counter_values = alloca (sizeof *counter_values * self->n_cpu * 2);
for (i = 0; i < self->n_cpu; i++)
for (guint i = 0; i < self->n_cpu; i++)
{
CpuInfo *info = &g_array_index (self->cpu_info, CpuInfo, i);
SpCaptureCounterValue *value = &counter_values[i*2];
@ -219,6 +250,7 @@ sp_hostinfo_source_finalize (GObject *object)
g_clear_pointer (&self->writer, sp_capture_writer_unref);
g_clear_pointer (&self->cpu_info, g_array_unref);
g_clear_pointer (&self->stat_buf, g_free);
G_OBJECT_CLASS (sp_hostinfo_source_parent_class)->finalize (object);
}
@ -234,7 +266,9 @@ sp_hostinfo_source_class_init (SpHostinfoSourceClass *klass)
static void
sp_hostinfo_source_init (SpHostinfoSource *self)
{
self->stat_fd = -1;
self->cpu_info = g_array_new (FALSE, TRUE, sizeof (CpuInfo));
self->stat_buf = g_malloc (PROC_STAT_BUF_SIZE);
}
static void
@ -270,6 +304,12 @@ sp_hostinfo_source_stop (SpSource *source)
g_source_remove (self->handler);
self->handler = 0;
if (self->stat_fd != -1)
{
close (self->stat_fd);
self->stat_fd = -1;
}
sp_source_emit_finished (SP_SOURCE (self));
}
@ -278,17 +318,17 @@ sp_hostinfo_source_prepare (SpSource *source)
{
SpHostinfoSource *self = (SpHostinfoSource *)source;
SpCaptureCounter *counters;
gint i;
g_assert (SP_IS_HOSTINFO_SOURCE (self));
self->stat_fd = open ("/proc/stat", O_RDONLY);
self->n_cpu = g_get_num_processors ();
g_array_set_size (self->cpu_info, 0);
counters = alloca (sizeof *counters * self->n_cpu * 2);
for (i = 0; i < self->n_cpu; i++)
for (guint i = 0; i < self->n_cpu; i++)
{
SpCaptureCounter *ctr = &counters[i*2];
CpuInfo info = { 0 };