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gamemode: Apply io priority to clients

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This commit allows changing the io priority of the client to a value
specified in the configuration file. That can possibly reduce lags or
latency when a game has to load assets on demand and you have background
IO activity running (or other concurrent IO).

Signed-off-by: Kai Krakow <kai@kaishome.de>
This commit is contained in:
Kai Krakow
2018-09-30 17:40:25 +02:00
parent ebf177bebe
commit 62865b1e32
3 changed files with 138 additions and 0 deletions
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54
daemon/gamemode.c
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@@ -35,6 +35,7 @@ POSSIBILITY OF SUCH DAMAGE.
#include "daemon_config.h"
#include "governors-query.h"
#include "governors.h"
#include "ioprio.h"
#include "logging.h"
#include <linux/limits.h>
@@ -241,6 +242,56 @@ static void game_mode_apply_scheduler(GameModeContext *self, pid_t client)
}
}
/**
* Apply io priorities
*
* This tries to change the io priority of the client to a value specified
* and can possibly reduce lags or latency when a game has to load assets
* on demand.
*/
static void game_mode_apply_ioprio(GameModeContext *self, pid_t client)
{
LOG_MSG("Setting scheduling policies...\n");
/*
* read configuration "ioprio" (0..7)
*/
int ioprio = 0;
config_get_ioprio_value(self->config, &ioprio);
if (IOPRIO_RESET_DEFAULT == ioprio) {
LOG_MSG("IO priority will be reset to default behavior (based on CPU priority).\n");
ioprio = 0;
} else if (IOPRIO_DONT_SET == ioprio) {
return;
} else {
/* maybe clamp the value */
int invalid_ioprio = ioprio;
ioprio = CLAMP(0, 7, ioprio);
if (ioprio != invalid_ioprio)
LOG_ERROR("IO priority value %d invalid, clamping to %d\n", invalid_ioprio, ioprio);
/* We support only IOPRIO_CLASS_BE as IOPRIO_CLASS_RT required CAP_SYS_ADMIN */
ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, ioprio);
}
/*
* Actually apply the io priority
*/
int c = IOPRIO_PRIO_CLASS(ioprio), p = IOPRIO_PRIO_DATA(ioprio);
if (ioprio_set(IOPRIO_WHO_PROCESS, client, ioprio) == 0) {
if (0 == ioprio)
LOG_MSG("Resetting client [%d] IO priority.\n", client);
else
LOG_MSG("Setting client [%d] IO priority to (%d,%d).\n", client, c, p);
} else {
LOG_ERROR("Setting client [%d] IO priority to (%d,%d) failed with error %d, ignoring\n",
client,
c,
p,
errno);
}
}
/**
* Pivot into game mode.
*
@@ -437,6 +488,9 @@ bool game_mode_context_register(GameModeContext *self, pid_t client)
/* Apply scheduler policies */
game_mode_apply_scheduler(self, client);
/* Apply io priorities */
game_mode_apply_ioprio(self, client);
return true;
error_cleanup:
game_mode_client_free(cl);