Subject: timer: add a mod_timer_msec() API function
From: Arjan van de Ven <[email protected]>
There is a common pattern in the kernel, where the caller wants
to set a timer a specified number of milliseconds into the future.
The typical solution then ends up
mod_timer(&timer, jiffies + msecs_to_jiffies(msec_amount));
or
mod_timer(&timer, jiffies + HZ/some_value);
This patch aims to simplify this pattern for the caller, and at
the same time, make for a more power-friendly API.
The new pattern for identical behavior will be
mod_timer_msec(&timer, msec_amount, 0);
while
mod_timer_msec(&time, msec_amount, 100);
would give the kernel 100 milliseconds of slack to find a power
friendly time to group timers into one CPU wakeup.
A patch to convert a number of users, to show how the API is used,
will be sent as reply to this email.
Signed-off-by: Arjan van de Ven <[email protected]>
diff --git a/include/linux/timer.h b/include/linux/timer.h
index a2d1eb6..006d4da 100644
--- a/include/linux/timer.h
+++ b/include/linux/timer.h
@@ -162,6 +162,7 @@ static inline int timer_pending(const struct timer_list * timer)
extern void add_timer_on(struct timer_list *timer, int cpu);
extern int del_timer(struct timer_list * timer);
extern int mod_timer(struct timer_list *timer, unsigned long expires);
+extern int mod_timer_msec(struct timer_list *timer, unsigned long delay_ms, unsigned long slack_ms);
extern int mod_timer_pending(struct timer_list *timer, unsigned long expires);
extern int mod_timer_pinned(struct timer_list *timer, unsigned long expires);
diff --git a/kernel/timer.c b/kernel/timer.c
index 5db5a8d..c9d5cbf 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -751,6 +751,47 @@ int mod_timer(struct timer_list *timer, unsigned long expires)
EXPORT_SYMBOL(mod_timer);
/**
+ * mod_timer_msec - modify a timer's timeout, using relative milliseconds
+ * @timer: the timer to be modified
+ * @delay_ms: the desired minimum delay in milliseconds
+ * @slack_ms: the amount of slack is ok in firing the timer
+ *
+ * Changes the timeout of a timer similar to mod_timer().
+ *
+ * mod_timer_msec() takes relative milliseconds rather than absolute
+ * jiffies as argument and also takes a "slack" amount, which is
+ * an explicit permission to treat the time of the timer as less
+ * precise in order to allow grouping of timers.
+ *
+ * The function returns whether it has modified a pending timer or not.
+ * (ie. mod_timer() of an inactive timer returns 0, mod_timer() of an
+ * active timer returns 1.)
+ */
+int mod_timer_msec(struct timer_list *timer, unsigned long delay_ms, unsigned long slack_ms)
+{
+ unsigned long next_jiffies, max_jiffies;
+ unsigned long rounded_jiffies;
+
+ next_jiffies = jiffies + msecs_to_jiffies(delay_ms);
+ max_jiffies = jiffies + msecs_to_jiffies(delay_ms + slack_ms);
+ rounded_jiffies = round_jiffies(next_jiffies);
+
+ /* check if rounding up next_jiffies is within the max */
+ if (rounded_jiffies <= max_jiffies && rounded_jiffies >= next_jiffies) {
+ next_jiffies = rounded_jiffies;
+ } else {
+ /* regular rounding failed; try a rounding to multiple-of-16 */
+ rounded_jiffies = (next_jiffies + 15) & ~0xF;
+ if (rounded_jiffies <= max_jiffies)
+ next_jiffies = rounded_jiffies;
+ }
+
+ return mod_timer(timer, next_jiffies);
+}
+EXPORT_SYMBOL_GPL(mod_timer_msec);
+
+
+/**
* mod_timer_pinned - modify a timer's timeout
* @timer: the timer to be modified
* @expires: new timeout in jiffies
--
Arjan van de Ven Intel Open Source Technology Centre
For development, discussion and tips for power savings,
visit http://www.lesswatts.org
Users of the new API;
these will be split up and sent to the various maintainers
once there is agreement on the API; for now this is just to
show how the API will be used.
diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
index d8f2145..758d1ce 100644
--- a/drivers/ata/ahci.c
+++ b/drivers/ata/ahci.c
@@ -1373,7 +1373,7 @@ static void ahci_sw_activity(struct ata_link *link)
emp->activity++;
if (!timer_pending(&emp->timer))
- mod_timer(&emp->timer, jiffies + msecs_to_jiffies(10));
+ mod_timer_msec(&emp->timer, 10, 1);
}
static void ahci_sw_activity_blink(unsigned long arg)
@@ -1409,7 +1409,7 @@ static void ahci_sw_activity_blink(unsigned long arg)
/* toggle state */
led_message |= (activity_led_state << 16);
- mod_timer(&emp->timer, jiffies + msecs_to_jiffies(100));
+ mod_timer_msec(&emp->timer, 100, 5);
} else {
/* switch to idle */
led_message &= ~EM_MSG_LED_VALUE_ACTIVITY;
diff --git a/drivers/bluetooth/bluecard_cs.c b/drivers/bluetooth/bluecard_cs.c
index b0e569b..54005e2 100644
--- a/drivers/bluetooth/bluecard_cs.c
+++ b/drivers/bluetooth/bluecard_cs.c
@@ -188,13 +188,13 @@ static void bluecard_enable_activity_led(bluecard_info_t *info)
outb(0x10 | 0x40, iobase + 0x30);
/* Stop the LED after HZ/4 */
- mod_timer(&(info->timer), jiffies + HZ / 4);
+ mod_timer_msec(&(info->timer), 250, 20);
} else {
/* Enable power LED */
outb(0x08 | 0x20, iobase + 0x30);
/* Stop the LED after HZ/2 */
- mod_timer(&(info->timer), jiffies + HZ / 2);
+ mod_timer_msec(&(info->timer), 500, 40);
}
}
diff --git a/drivers/bluetooth/hci_bcsp.c b/drivers/bluetooth/hci_bcsp.c
index 40aec0f..5c2189f 100644
--- a/drivers/bluetooth/hci_bcsp.c
+++ b/drivers/bluetooth/hci_bcsp.c
@@ -312,7 +312,7 @@ static struct sk_buff *bcsp_dequeue(struct hci_uart *hu)
struct sk_buff *nskb = bcsp_prepare_pkt(bcsp, skb->data, skb->len, bt_cb(skb)->pkt_type);
if (nskb) {
__skb_queue_tail(&bcsp->unack, skb);
- mod_timer(&bcsp->tbcsp, jiffies + HZ / 4);
+ mod_timer_msec(&bcsp->tbcsp, 250, 20);
spin_unlock_irqrestore(&bcsp->unack.lock, flags);
return nskb;
} else {
diff --git a/drivers/char/isicom.c b/drivers/char/isicom.c
index 426bfdd..cc9e7b4 100644
--- a/drivers/char/isicom.c
+++ b/drivers/char/isicom.c
@@ -506,7 +506,7 @@ unlock:
spin_unlock_irqrestore(&isi_card[card].card_lock, flags);
/* schedule another tx for hopefully in about 10ms */
sched_again:
- mod_timer(&tx, jiffies + msecs_to_jiffies(10));
+ mod_timer_msec(&tx, 10, 0);
}
/*
diff --git a/drivers/char/moxa.c b/drivers/char/moxa.c
index dd0083b..4ad6113 100644
--- a/drivers/char/moxa.c
+++ b/drivers/char/moxa.c
@@ -869,7 +869,7 @@ static int moxa_init_board(struct moxa_board_conf *brd, struct device *dev)
spin_lock_bh(&moxa_lock);
brd->ready = 1;
if (!timer_pending(&moxaTimer))
- mod_timer(&moxaTimer, jiffies + HZ / 50);
+ mod_timer_msec(&moxaTimer, 20, 0);
spin_unlock_bh(&moxa_lock);
return 0;
@@ -1556,7 +1556,7 @@ static void moxa_poll(unsigned long ignored)
moxaLowWaterChk = 0;
if (served)
- mod_timer(&moxaTimer, jiffies + HZ / 50);
+ mod_timer_msec(&moxaTimer, 20, 0);
spin_unlock(&moxa_lock);
}
diff --git a/drivers/char/synclink.c b/drivers/char/synclink.c
index 4846b73..63d5b70 100644
--- a/drivers/char/synclink.c
+++ b/drivers/char/synclink.c
@@ -4024,7 +4024,7 @@ static bool load_next_tx_holding_buffer(struct mgsl_struct *info)
info->get_tx_holding_index=0;
/* restart transmit timer */
- mod_timer(&info->tx_timer, jiffies + msecs_to_jiffies(5000));
+ mod_timer_msec(&info->tx_timer, 5000, 100);
ret = true;
}
@@ -5653,8 +5653,7 @@ static void usc_start_transmitter( struct mgsl_struct *info )
usc_TCmd( info, TCmd_SendFrame );
- mod_timer(&info->tx_timer, jiffies +
- msecs_to_jiffies(5000));
+ mod_timer_msec(&info->tx_timer, 5000, 100);
}
info->tx_active = true;
}
diff --git a/drivers/char/synclink_gt.c b/drivers/char/synclink_gt.c
index 8678f0c..58402a0 100644
--- a/drivers/char/synclink_gt.c
+++ b/drivers/char/synclink_gt.c
@@ -803,7 +803,7 @@ static void update_tx_timer(struct slgt_info *info)
*/
if (info->params.mode == MGSL_MODE_HDLC) {
int timeout = (tbuf_bytes(info) * 7) + 1000;
- mod_timer(&info->tx_timer, jiffies + msecs_to_jiffies(timeout));
+ mod_timer_msec(&info->tx_timer, timeout, 0);
}
}
diff --git a/drivers/char/synclinkmp.c b/drivers/char/synclinkmp.c
index 2b18adc..b032af6 100644
--- a/drivers/char/synclinkmp.c
+++ b/drivers/char/synclinkmp.c
@@ -2685,7 +2685,7 @@ static int startup(SLMP_INFO * info)
change_params(info);
- mod_timer(&info->status_timer, jiffies + msecs_to_jiffies(10));
+ mod_timer_msec(&info->status_timer, 10, 0);
if (info->port.tty)
clear_bit(TTY_IO_ERROR, &info->port.tty->flags);
@@ -4252,8 +4252,7 @@ static void tx_start(SLMP_INFO *info)
write_reg(info, TXDMA + DIR, 0x40); /* enable Tx DMA interrupts (EOM) */
write_reg(info, TXDMA + DSR, 0xf2); /* clear Tx DMA IRQs, enable Tx DMA */
- mod_timer(&info->tx_timer, jiffies +
- msecs_to_jiffies(5000));
+ mod_timer_msec(&info->tx_timer, 5000, 100);
}
else {
tx_load_fifo(info);
@@ -5534,7 +5533,7 @@ static void status_timeout(unsigned long context)
if (status)
isr_io_pin(info,status);
- mod_timer(&info->status_timer, jiffies + msecs_to_jiffies(10));
+ mod_timer_msec(&info->status_timer, 10, 0);
}
diff --git a/drivers/input/gameport/gameport.c b/drivers/input/gameport/gameport.c
index ac11be0..8b391b2 100644
--- a/drivers/input/gameport/gameport.c
+++ b/drivers/input/gameport/gameport.c
@@ -147,7 +147,7 @@ void gameport_start_polling(struct gameport *gameport)
if (!gameport->poll_cnt++) {
BUG_ON(!gameport->poll_handler);
BUG_ON(!gameport->poll_interval);
- mod_timer(&gameport->poll_timer, jiffies + msecs_to_jiffies(gameport->poll_interval));
+ mod_timer_msec(&gameport->poll_timer, gameport->poll_interval, 0);
}
spin_unlock(&gameport->timer_lock);
@@ -171,7 +171,7 @@ static void gameport_run_poll_handler(unsigned long d)
gameport->poll_handler(gameport);
if (gameport->poll_cnt)
- mod_timer(&gameport->poll_timer, jiffies + msecs_to_jiffies(gameport->poll_interval));
+ mod_timer_msec(&gameport->poll_timer, gameport->poll_interval, 0);
}
/*
diff --git a/drivers/input/keyboard/corgikbd.c b/drivers/input/keyboard/corgikbd.c
index 634af6a..d49846f 100644
--- a/drivers/input/keyboard/corgikbd.c
+++ b/drivers/input/keyboard/corgikbd.c
@@ -179,7 +179,7 @@ static void corgikbd_scankeyboard(struct corgikbd *corgikbd_data)
/* if any keys are pressed, enable the timer */
if (num_pressed)
- mod_timer(&corgikbd_data->timer, jiffies + msecs_to_jiffies(SCAN_INTERVAL));
+ mod_timer_msec(&corgikbd_data->timer, SCAN_INTERVAL, 0);
spin_unlock_irqrestore(&corgikbd_data->lock, flags);
}
@@ -249,7 +249,7 @@ static void corgikbd_hinge_timer(unsigned long data)
spin_unlock_irqrestore(&corgikbd_data->lock, flags);
}
}
- mod_timer(&corgikbd_data->htimer, jiffies + msecs_to_jiffies(HINGE_SCAN_INTERVAL));
+ mod_timer_msec(&corgikbd_data->htimer, HINGE_SCAN_INTERVAL, 0);
}
#ifdef CONFIG_PM
@@ -341,7 +341,7 @@ static int __devinit corgikbd_probe(struct platform_device *pdev)
if (err)
goto fail;
- mod_timer(&corgikbd->htimer, jiffies + msecs_to_jiffies(HINGE_SCAN_INTERVAL));
+ mod_timer_msec(&corgikbd->htimer, HINGE_SCAN_INTERVAL, 0);
/* Setup sense interrupts - RisingEdge Detect, sense lines as inputs */
for (i = 0; i < CORGI_KEY_SENSE_NUM; i++) {
diff --git a/drivers/input/keyboard/spitzkbd.c b/drivers/input/keyboard/spitzkbd.c
index 1396742..c64e4d0 100644
--- a/drivers/input/keyboard/spitzkbd.c
+++ b/drivers/input/keyboard/spitzkbd.c
@@ -228,7 +228,7 @@ static void spitzkbd_scankeyboard(struct spitzkbd *spitzkbd_data)
/* if any keys are pressed, enable the timer */
if (num_pressed)
- mod_timer(&spitzkbd_data->timer, jiffies + msecs_to_jiffies(SCAN_INTERVAL));
+ mod_timer_msec(&spitzkbd_data->timer, SCAN_INTERVAL, 0);
spin_unlock_irqrestore(&spitzkbd_data->lock, flags);
}
@@ -269,7 +269,7 @@ static irqreturn_t spitzkbd_hinge_isr(int irq, void *dev_id)
struct spitzkbd *spitzkbd_data = dev_id;
if (!timer_pending(&spitzkbd_data->htimer))
- mod_timer(&spitzkbd_data->htimer, jiffies + msecs_to_jiffies(HINGE_SCAN_INTERVAL));
+ mod_timer_msec(&spitzkbd_data->htimer, HINGE_SCAN_INTERVAL, 0);
return IRQ_HANDLED;
}
@@ -303,7 +303,7 @@ static void spitzkbd_hinge_timer(unsigned long data)
spin_unlock_irqrestore(&spitzkbd_data->lock, flags);
} else {
- mod_timer(&spitzkbd_data->htimer, jiffies + msecs_to_jiffies(HINGE_SCAN_INTERVAL));
+ mod_timer_msec(&spitzkbd_data->htimer, HINGE_SCAN_INTERVAL, 0);
}
}
@@ -399,7 +399,7 @@ static int __devinit spitzkbd_probe(struct platform_device *dev)
if (err)
goto fail;
- mod_timer(&spitzkbd->htimer, jiffies + msecs_to_jiffies(HINGE_SCAN_INTERVAL));
+ mod_timer_msec(&spitzkbd->htimer, HINGE_SCAN_INTERVAL, 0);
/* Setup sense interrupts - RisingEdge Detect, sense lines as inputs */
for (i = 0; i < SPITZ_KEY_SENSE_NUM; i++) {
diff --git a/drivers/input/touchscreen/corgi_ts.c b/drivers/input/touchscreen/corgi_ts.c
index 94a1919..031ca5c 100644
--- a/drivers/input/touchscreen/corgi_ts.c
+++ b/drivers/input/touchscreen/corgi_ts.c
@@ -199,10 +199,10 @@ static void ts_interrupt_main(struct corgi_ts *corgi_ts, int isTimer)
corgi_ts->pendown = 1;
new_data(corgi_ts);
}
- mod_timer(&corgi_ts->timer, jiffies + HZ / 100);
+ mod_timer_msec(&corgi_ts->timer, 10, 0);
} else {
if (corgi_ts->pendown == 1 || corgi_ts->pendown == 2) {
- mod_timer(&corgi_ts->timer, jiffies + HZ / 100);
+ mod_timer_msec(&corgi_ts->timer, 10, 0);
corgi_ts->pendown++;
return;
}
diff --git a/drivers/input/touchscreen/w90p910_ts.c b/drivers/input/touchscreen/w90p910_ts.c
index 6ccbdbb..a39e07e 100644
--- a/drivers/input/touchscreen/w90p910_ts.c
+++ b/drivers/input/touchscreen/w90p910_ts.c
@@ -133,7 +133,7 @@ static irqreturn_t w90p910_ts_interrupt(int irq, void *dev_id)
case TS_WAIT_Y_COORD:
w90p910_report_event(w90p910_ts, true);
w90p910_prepare_next_packet(w90p910_ts);
- mod_timer(&w90p910_ts->timer, jiffies + msecs_to_jiffies(100));
+ mod_timer_msec(&w90p910_ts->timer, 100, 0);
break;
case TS_IDLE:
diff --git a/drivers/isdn/gigaset/common.c b/drivers/isdn/gigaset/common.c
index 33dcd8d..83cd958 100644
--- a/drivers/isdn/gigaset/common.c
+++ b/drivers/isdn/gigaset/common.c
@@ -179,7 +179,7 @@ static void timer_tick(unsigned long data)
timeout = 1;
if (cs->running) {
- mod_timer(&cs->timer, jiffies + msecs_to_jiffies(GIG_TICK));
+ mod_timer_msec(&cs->timer, GIG_TICK, 0);
if (timeout) {
gig_dbg(DEBUG_CMD, "scheduling timeout");
tasklet_schedule(&cs->event_tasklet);
diff --git a/drivers/leds/ledtrig-ide-disk.c b/drivers/leds/ledtrig-ide-disk.c
index ec099fc..0667bf4 100644
--- a/drivers/leds/ledtrig-ide-disk.c
+++ b/drivers/leds/ledtrig-ide-disk.c
@@ -29,7 +29,7 @@ void ledtrig_ide_activity(void)
{
ide_activity++;
if (!timer_pending(&ledtrig_ide_timer))
- mod_timer(&ledtrig_ide_timer, jiffies + msecs_to_jiffies(10));
+ mod_timer_msec(&ledtrig_ide_timer, 10, 0);
}
EXPORT_SYMBOL(ledtrig_ide_activity);
@@ -39,7 +39,7 @@ static void ledtrig_ide_timerfunc(unsigned long data)
ide_lastactivity = ide_activity;
/* INT_MAX will set each LED to its maximum brightness */
led_trigger_event(ledtrig_ide, INT_MAX);
- mod_timer(&ledtrig_ide_timer, jiffies + msecs_to_jiffies(10));
+ mod_timer_msec(&ledtrig_ide_timer, 10, 0);
} else {
led_trigger_event(ledtrig_ide, LED_OFF);
}
diff --git a/drivers/leds/ledtrig-timer.c b/drivers/leds/ledtrig-timer.c
index 3b83406..d136ad5 100644
--- a/drivers/leds/ledtrig-timer.c
+++ b/drivers/leds/ledtrig-timer.c
@@ -61,7 +61,7 @@ static void led_timer_function(unsigned long data)
led_set_brightness(led_cdev, brightness);
- mod_timer(&timer_data->timer, jiffies + msecs_to_jiffies(delay));
+ mod_timer_msec(&timer_data->timer, delay, 0);
}
static ssize_t led_delay_on_show(struct device *dev,
diff --git a/drivers/media/dvb/ttpci/budget-ci.c b/drivers/media/dvb/ttpci/budget-ci.c
index b5c6813..9ec51a7 100644
--- a/drivers/media/dvb/ttpci/budget-ci.c
+++ b/drivers/media/dvb/ttpci/budget-ci.c
@@ -182,7 +182,7 @@ static void msp430_ir_interrupt(unsigned long data)
budget_ci->ir.last_raw = raw;
}
- mod_timer(&budget_ci->ir.timer_keyup, jiffies + msecs_to_jiffies(IR_KEYPRESS_TIMEOUT));
+ mod_timer_msec(&budget_ci->ir.timer_keyup, IR_KEYPRESS_TIMEOUT, 0);
}
static int msp430_ir_init(struct budget_ci *budget_ci)
diff --git a/drivers/media/video/bt8xx/bttv-input.c b/drivers/media/video/bt8xx/bttv-input.c
index ebd51af..6448149 100644
--- a/drivers/media/video/bt8xx/bttv-input.c
+++ b/drivers/media/video/bt8xx/bttv-input.c
@@ -141,7 +141,7 @@ static void bttv_input_timer(unsigned long data)
ir_enltv_handle_key(btv);
else
ir_handle_key(btv);
- mod_timer(&ir->timer, jiffies + msecs_to_jiffies(ir->polling));
+ mod_timer_msec(&ir->timer, ir->polling, 0);
}
/* ---------------------------------------------------------------*/
diff --git a/drivers/media/video/cx231xx/cx231xx-input.c b/drivers/media/video/cx231xx/cx231xx-input.c
index 48f22fa..4101a06 100644
--- a/drivers/media/video/cx231xx/cx231xx-input.c
+++ b/drivers/media/video/cx231xx/cx231xx-input.c
@@ -147,7 +147,7 @@ static void cx231xx_ir_work(struct work_struct *work)
struct cx231xx_IR *ir = container_of(work, struct cx231xx_IR, work);
cx231xx_ir_handle_key(ir);
- mod_timer(&ir->timer, jiffies + msecs_to_jiffies(ir->polling));
+ mod_timer_msec(&ir->timer, ir->polling, 0);
}
void cx231xx_ir_start(struct cx231xx_IR *ir)
diff --git a/drivers/media/video/saa7134/saa7134-input.c b/drivers/media/video/saa7134/saa7134-input.c
index a0e8c62..a45510c 100644
--- a/drivers/media/video/saa7134/saa7134-input.c
+++ b/drivers/media/video/saa7134/saa7134-input.c
@@ -358,7 +358,7 @@ static void saa7134_input_timer(unsigned long data)
struct card_ir *ir = dev->remote;
build_key(dev);
- mod_timer(&ir->timer, jiffies + msecs_to_jiffies(ir->polling));
+ mod_timer_msec(&ir->timer, ir->polling, 0);
}
void saa7134_ir_start(struct saa7134_dev *dev, struct card_ir *ir)
@@ -941,7 +941,7 @@ static void nec_task(unsigned long data)
dprintk("Repeat last key\n");
/* Keep repeating the last key */
- mod_timer(&ir->timer_keyup, jiffies + msecs_to_jiffies(150));
+ mod_timer_msec(&ir->timer_keyup, 150, 0);
saa_setl(SAA7134_IRQ2, SAA7134_IRQ2_INTE_GPIO18);
}
diff --git a/drivers/media/video/tvaudio.c b/drivers/media/video/tvaudio.c
index 0869baf..47c58c8 100644
--- a/drivers/media/video/tvaudio.c
+++ b/drivers/media/video/tvaudio.c
@@ -329,7 +329,7 @@ static int chip_thread(void *data)
desc->setmode(chip, V4L2_TUNER_MODE_MONO);
/* schedule next check */
- mod_timer(&chip->wt, jiffies+msecs_to_jiffies(2000));
+ mod_timer_msec(&chip->wt, 2000, 100);
}
v4l2_dbg(1, debug, sd, "thread exiting\n");
@@ -1893,7 +1893,7 @@ static int tvaudio_s_frequency(struct v4l2_subdev *sd, struct v4l2_frequency *fr
desc->setmode(chip, V4L2_TUNER_MODE_MONO);
if (chip->prevmode != V4L2_TUNER_MODE_MONO)
chip->prevmode = -1; /* reset previous mode */
- mod_timer(&chip->wt, jiffies+msecs_to_jiffies(2000));
+ mod_timer_msec(&chip->wt, 2000, 100);
}
return 0;
}
diff --git a/drivers/mmc/host/atmel-mci.c b/drivers/mmc/host/atmel-mci.c
index fc25586..b1255c3 100644
--- a/drivers/mmc/host/atmel-mci.c
+++ b/drivers/mmc/host/atmel-mci.c
@@ -1471,7 +1471,7 @@ static irqreturn_t atmci_detect_interrupt(int irq, void *dev_id)
* middle of the timer routine when this interrupt triggers.
*/
disable_irq_nosync(irq);
- mod_timer(&slot->detect_timer, jiffies + msecs_to_jiffies(20));
+ mod_timer_msec(&slot->detect_timer, 20, 0);
return IRQ_HANDLED;
}
diff --git a/drivers/mmc/host/wbsd.c b/drivers/mmc/host/wbsd.c
index 89bf8cd..2f60f5d 100644
--- a/drivers/mmc/host/wbsd.c
+++ b/drivers/mmc/host/wbsd.c
@@ -906,7 +906,7 @@ static void wbsd_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
* We cannot resume card detection immediatly
* because of capacitance and delays in the chip.
*/
- mod_timer(&host->ignore_timer, jiffies + HZ / 100);
+ mod_timer_msec(&host->ignore_timer, 10, 0);
}
}
wbsd_write_index(host, WBSD_IDX_SETUP, setup);
diff --git a/drivers/net/s2io.c b/drivers/net/s2io.c
index 0dd7839..ba3a0c2 100644
--- a/drivers/net/s2io.c
+++ b/drivers/net/s2io.c
@@ -4309,7 +4309,7 @@ s2io_alarm_handle(unsigned long data)
struct net_device *dev = sp->dev;
s2io_handle_errors(dev);
- mod_timer(&sp->alarm_timer, jiffies + HZ / 2);
+ mod_timer_msec(&sp->alarm_timer, 500, 0);
}
static irqreturn_t s2io_msix_ring_handle(int irq, void *dev_id)
@@ -5483,7 +5483,7 @@ static void s2io_phy_id(unsigned long data)
writeq(val64, &bar0->adapter_control);
}
- mod_timer(&sp->id_timer, jiffies + HZ / 2);
+ mod_timer_msec(&sp->id_timer, 500, 0);
}
/**
diff --git a/drivers/net/wireless/at76c50x-usb.c b/drivers/net/wireless/at76c50x-usb.c
index 8e1a55d..616de6d 100644
--- a/drivers/net/wireless/at76c50x-usb.c
+++ b/drivers/net/wireless/at76c50x-usb.c
@@ -551,7 +551,7 @@ static void at76_ledtrig_tx_timerfunc(unsigned long data)
if (tx_lastactivity != tx_activity) {
tx_lastactivity = tx_activity;
led_trigger_event(ledtrig_tx, LED_FULL);
- mod_timer(&ledtrig_tx_timer, jiffies + HZ / 4);
+ mod_timer_msec(&ledtrig_tx_timer, 250, 0);
} else
led_trigger_event(ledtrig_tx, LED_OFF);
}
@@ -560,7 +560,7 @@ static void at76_ledtrig_tx_activity(void)
{
tx_activity++;
if (!timer_pending(&ledtrig_tx_timer))
- mod_timer(&ledtrig_tx_timer, jiffies + HZ / 4);
+ mod_timer_msec(&ledtrig_tx_timer, 250, 0);
}
static int at76_remap(struct usb_device *udev)
diff --git a/drivers/net/wireless/ath/ath9k/main.c b/drivers/net/wireless/ath/ath9k/main.c
index 52bed89..e0bb24e 100644
--- a/drivers/net/wireless/ath/ath9k/main.c
+++ b/drivers/net/wireless/ath/ath9k/main.c
@@ -416,7 +416,7 @@ set_timer:
if (!sc->ani.caldone)
cal_interval = min(cal_interval, (u32)short_cal_interval);
- mod_timer(&sc->ani.timer, jiffies + msecs_to_jiffies(cal_interval));
+ mod_timer_msec(&sc->ani.timer, cal_interval, 0);
}
static void ath_start_ani(struct ath_softc *sc)
@@ -427,8 +427,7 @@ static void ath_start_ani(struct ath_softc *sc)
sc->ani.shortcal_timer = timestamp;
sc->ani.checkani_timer = timestamp;
- mod_timer(&sc->ani.timer,
- jiffies + msecs_to_jiffies(ATH_ANI_POLLINTERVAL));
+ mod_timer_msec(&sc->ani.timer, ATH_ANI_POLLINTERVAL, 0);
}
/*
diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c
index 1840a05..7efee46 100644
--- a/drivers/pci/intel-iommu.c
+++ b/drivers/pci/intel-iommu.c
@@ -2703,7 +2703,7 @@ static void add_unmap(struct dmar_domain *dom, struct iova *iova)
deferred_flush[iommu_id].next++;
if (!timer_on) {
- mod_timer(&unmap_timer, jiffies + msecs_to_jiffies(10));
+ mod_timer_msec(&unmap_timer, 10, 0);
timer_on = 1;
}
list_size++;
diff --git a/drivers/scsi/bfa/bfad.c b/drivers/scsi/bfa/bfad.c
index 6f2be5a..d7e26d4 100644
--- a/drivers/scsi/bfa/bfad.c
+++ b/drivers/scsi/bfa/bfad.c
@@ -558,7 +558,7 @@ bfad_bfa_tmo(unsigned long data)
spin_unlock_irqrestore(&bfad->bfad_lock, flags);
}
- mod_timer(&bfad->hal_tmo, jiffies + msecs_to_jiffies(BFA_TIMER_FREQ));
+ mod_timer_msec(&bfad->hal_tmo, BFA_TIMER_FREQ, 0);
}
void
@@ -568,7 +568,7 @@ bfad_init_timer(struct bfad_s *bfad)
bfad->hal_tmo.function = bfad_bfa_tmo;
bfad->hal_tmo.data = (unsigned long)bfad;
- mod_timer(&bfad->hal_tmo, jiffies + msecs_to_jiffies(BFA_TIMER_FREQ));
+ mod_timer_msec(&bfad->hal_tmo, BFA_TIMER_FREQ, 0);
}
int
diff --git a/drivers/scsi/cxgb3i/cxgb3i_offload.c b/drivers/scsi/cxgb3i/cxgb3i_offload.c
index c1d5be4..6941151 100644
--- a/drivers/scsi/cxgb3i/cxgb3i_offload.c
+++ b/drivers/scsi/cxgb3i/cxgb3i_offload.c
@@ -838,7 +838,7 @@ static void process_act_open_rpl(struct s3_conn *c3cn, struct sk_buff *skb)
if (rpl->status == CPL_ERR_CONN_EXIST &&
c3cn->retry_timer.function != act_open_retry_timer) {
c3cn->retry_timer.function = act_open_retry_timer;
- if (!mod_timer(&c3cn->retry_timer, jiffies + HZ / 2))
+ if (!mod_timer_msec(&c3cn->retry_timer, 500, 0))
c3cn_hold(c3cn);
} else
fail_act_open(c3cn, act_open_rpl_status_to_errno(rpl->status));
diff --git a/drivers/staging/otus/usbdrv.c b/drivers/staging/otus/usbdrv.c
index 48aa30a..c4a03be 100644
--- a/drivers/staging/otus/usbdrv.c
+++ b/drivers/staging/otus/usbdrv.c
@@ -397,7 +397,7 @@ int usbdrv_open(struct net_device *dev)
zfLnxCreateThread(dev);
- mod_timer(&(macp->hbTimer10ms), jiffies + (1*HZ)/100); //10 ms
+ mod_timer_msec(&(macp->hbTimer10ms), 10, 0);
netif_carrier_on(dev);
@@ -711,7 +711,7 @@ void zfLnx10msTimer(struct net_device* dev)
{
struct usbdrv_private *macp = dev->ml_priv;
- mod_timer(&(macp->hbTimer10ms), jiffies + (1*HZ)/100); //10 ms
+ mod_timer_msec(&(macp->hbTimer10ms), 10, 0);
zfiHeartBeat(dev);
return;
}
diff --git a/drivers/usb/atm/speedtch.c b/drivers/usb/atm/speedtch.c
index 3e86240..375cf55 100644
--- a/drivers/usb/atm/speedtch.c
+++ b/drivers/usb/atm/speedtch.c
@@ -582,7 +582,7 @@ static void speedtch_status_poll(unsigned long data)
/* The following check is racy, but the race is harmless */
if (instance->poll_delay < MAX_POLL_DELAY)
- mod_timer(&instance->status_checker.timer, jiffies + msecs_to_jiffies(instance->poll_delay));
+ mod_timer_msec(&instance->status_checker.timer, instance->poll_delay, 0);
else
atm_warn(instance->usbatm, "Too many failures - disabling line status polling\n");
}
@@ -601,7 +601,7 @@ static void speedtch_resubmit_int(unsigned long data)
schedule_delayed_work(&instance->status_checker, 0);
else {
atm_dbg(instance->usbatm, "%s: usb_submit_urb failed with result %d\n", __func__, ret);
- mod_timer(&instance->resubmit_timer, jiffies + msecs_to_jiffies(RESUBMIT_DELAY));
+ mod_timer_msec(&instance->resubmit_timer, RESUBMIT_DELAY, 0);
}
}
}
@@ -654,7 +654,7 @@ static void speedtch_handle_int(struct urb *int_urb)
fail:
if ((int_urb = instance->int_urb))
- mod_timer(&instance->resubmit_timer, jiffies + msecs_to_jiffies(RESUBMIT_DELAY));
+ mod_timer_msec(&instance->resubmit_timer, RESUBMIT_DELAY, 0);
}
static int speedtch_atm_start(struct usbatm_data *usbatm, struct atm_dev *atm_dev)
@@ -688,7 +688,7 @@ static int speedtch_atm_start(struct usbatm_data *usbatm, struct atm_dev *atm_de
}
/* Start status polling */
- mod_timer(&instance->status_checker.timer, jiffies + msecs_to_jiffies(1000));
+ mod_timer_msec(&instance->status_checker.timer, 1000, 50);
return 0;
}
diff --git a/drivers/usb/atm/usbatm.c b/drivers/usb/atm/usbatm.c
index fbea856..79481ea 100644
--- a/drivers/usb/atm/usbatm.c
+++ b/drivers/usb/atm/usbatm.c
@@ -248,7 +248,7 @@ static int usbatm_submit_urb(struct urb *urb)
spin_unlock_irq(&channel->lock);
/* make sure the channel doesn't stall */
- mod_timer(&channel->delay, jiffies + msecs_to_jiffies(THROTTLE_MSECS));
+ mod_timer_msec(&channel->delay, THROTTLE_MSECS, 0);
}
return ret;
@@ -282,7 +282,7 @@ static void usbatm_complete(struct urb *urb)
atm_warn(channel->usbatm, "%s: urb 0x%p failed (%d)!\n",
__func__, urb, status);
/* throttle processing in case of an error */
- mod_timer(&channel->delay, jiffies + msecs_to_jiffies(THROTTLE_MSECS));
+ mod_timer_msec(&channel->delay, THROTTLE_MSECS, 0);
} else
tasklet_schedule(&channel->tasklet);
}
diff --git a/drivers/usb/gadget/dummy_hcd.c b/drivers/usb/gadget/dummy_hcd.c
index 5e09664..83d6bc2 100644
--- a/drivers/usb/gadget/dummy_hcd.c
+++ b/drivers/usb/gadget/dummy_hcd.c
@@ -1520,7 +1520,7 @@ return_urb:
dum->udev = NULL;
} else if (dum->rh_state == DUMMY_RH_RUNNING) {
/* want a 1 msec delay here */
- mod_timer (&dum->timer, jiffies + msecs_to_jiffies(1));
+ mod_timer_msec (&dum->timer, 1, 0);
}
spin_unlock_irqrestore (&dum->lock, flags);
diff --git a/drivers/usb/gadget/m66592-udc.c b/drivers/usb/gadget/m66592-udc.c
index a8c8543..7428f94 100644
--- a/drivers/usb/gadget/m66592-udc.c
+++ b/drivers/usb/gadget/m66592-udc.c
@@ -1229,8 +1229,7 @@ static irqreturn_t m66592_irq(int irq, void *_m66592)
& M66592_VBSTS;
m66592->scount = M66592_MAX_SAMPLING;
- mod_timer(&m66592->timer,
- jiffies + msecs_to_jiffies(50));
+ mod_timer_msec(&m66592->timer, 50, 0);
}
if (intsts0 & M66592_DVSQ)
irq_device_state(m66592);
@@ -1277,14 +1276,12 @@ static void m66592_timer(unsigned long _m66592)
else
m66592_usb_disconnect(m66592);
} else {
- mod_timer(&m66592->timer,
- jiffies + msecs_to_jiffies(50));
+ mod_timer_msec(&m66592->timer, 50, 0);
}
} else {
m66592->scount = M66592_MAX_SAMPLING;
m66592->old_vbus = tmp;
- mod_timer(&m66592->timer,
- jiffies + msecs_to_jiffies(50));
+ mod_timer_msec(&m66592->timer, 50, 0);
}
}
spin_unlock_irqrestore(&m66592->lock, flags);
@@ -1493,7 +1490,7 @@ int usb_gadget_register_driver(struct usb_gadget_driver *driver)
m66592->old_vbus = m66592_read(m66592,
M66592_INTSTS0) & M66592_VBSTS;
m66592->scount = M66592_MAX_SAMPLING;
- mod_timer(&m66592->timer, jiffies + msecs_to_jiffies(50));
+ mod_timer_msec(&m66592->timer, 50, 0);
}
return 0;
diff --git a/drivers/usb/gadget/r8a66597-udc.c b/drivers/usb/gadget/r8a66597-udc.c
index e220fb8..bb0d70b 100644
--- a/drivers/usb/gadget/r8a66597-udc.c
+++ b/drivers/usb/gadget/r8a66597-udc.c
@@ -1167,8 +1167,7 @@ static irqreturn_t r8a66597_irq(int irq, void *_r8a66597)
& VBSTS;
r8a66597->scount = R8A66597_MAX_SAMPLING;
- mod_timer(&r8a66597->timer,
- jiffies + msecs_to_jiffies(50));
+ mod_timer_msec(&r8a66597->timer, 50, 0);
}
if (intsts0 & DVSQ)
irq_device_state(r8a66597);
@@ -1208,14 +1207,12 @@ static void r8a66597_timer(unsigned long _r8a66597)
else
r8a66597_usb_disconnect(r8a66597);
} else {
- mod_timer(&r8a66597->timer,
- jiffies + msecs_to_jiffies(50));
+ mod_timer_msec(&r8a66597->timer, 50, 0);
}
} else {
r8a66597->scount = R8A66597_MAX_SAMPLING;
r8a66597->old_vbus = tmp;
- mod_timer(&r8a66597->timer,
- jiffies + msecs_to_jiffies(50));
+ mod_timer_msec(&r8a66597->timer, 50, 0);
}
}
spin_unlock_irqrestore(&r8a66597->lock, flags);
@@ -1443,7 +1440,7 @@ int usb_gadget_register_driver(struct usb_gadget_driver *driver)
r8a66597->old_vbus = r8a66597_read(r8a66597,
INTSTS0) & VBSTS;
r8a66597->scount = R8A66597_MAX_SAMPLING;
- mod_timer(&r8a66597->timer, jiffies + msecs_to_jiffies(50));
+ mod_timer_msec(&r8a66597->timer, 50, 0);
}
return 0;
diff --git a/net/dsa/mv88e6xxx.c b/net/dsa/mv88e6xxx.c
index efe661a..2680d65 100644
--- a/net/dsa/mv88e6xxx.c
+++ b/net/dsa/mv88e6xxx.c
@@ -309,7 +309,7 @@ static void mv88e6xxx_ppu_access_put(struct dsa_switch *ds)
/*
* Schedule a timer to re-enable the PHY polling unit.
*/
- mod_timer(&ps->ppu_timer, jiffies + msecs_to_jiffies(10));
+ mod_timer_msec(&ps->ppu_timer, 10, 0);
mutex_unlock(&ps->ppu_mutex);
}
diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index 99508d6..35476bd 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -371,7 +371,7 @@ static void ipmr_expire_process(unsigned long dummy)
struct mfc_cache *c, **cp;
if (!spin_trylock(&mfc_unres_lock)) {
- mod_timer(&ipmr_expire_timer, jiffies+HZ/10);
+ mod_timer_msec(&ipmr_expire_timer, 100, 0);
return;
}
diff --git a/net/sctp/sm_sideeffect.c b/net/sctp/sm_sideeffect.c
index 8674d49..4307e08 100644
--- a/net/sctp/sm_sideeffect.c
+++ b/net/sctp/sm_sideeffect.c
@@ -255,7 +255,7 @@ void sctp_generate_t3_rtx_event(unsigned long peer)
SCTP_DEBUG_PRINTK("%s:Sock is busy.\n", __func__);
/* Try again later. */
- if (!mod_timer(&transport->T3_rtx_timer, jiffies + (HZ/20)))
+ if (!mod_timer_msec(&transport->T3_rtx_timer, 50, 0))
sctp_transport_hold(transport);
goto out_unlock;
}
@@ -296,7 +296,7 @@ static void sctp_generate_timeout_event(struct sctp_association *asoc,
timeout_type);
/* Try again later. */
- if (!mod_timer(&asoc->timers[timeout_type], jiffies + (HZ/20)))
+ if (!mod_timer_msec(&asoc->timers[timeout_type], 50, 0))
sctp_association_hold(asoc);
goto out_unlock;
}
@@ -373,7 +373,7 @@ void sctp_generate_heartbeat_event(unsigned long data)
SCTP_DEBUG_PRINTK("%s:Sock is busy.\n", __func__);
/* Try again later. */
- if (!mod_timer(&transport->hb_timer, jiffies + (HZ/20)))
+ if (!mod_timer_msec(&transport->hb_timer, 50, 0))
sctp_transport_hold(transport);
goto out_unlock;
}
diff --git a/sound/soc/omap/ams-delta.c b/sound/soc/omap/ams-delta.c
index 5a5166a..842e8a4 100644
--- a/sound/soc/omap/ams-delta.c
+++ b/sound/soc/omap/ams-delta.c
@@ -338,7 +338,7 @@ static void cx81801_receive(struct tty_struct *tty,
/* Complete modem response received, apply config to codec */
spin_lock_bh(&ams_delta_lock);
- mod_timer(&cx81801_timer, jiffies + msecs_to_jiffies(150));
+ mod_timer_msec(&cx81801_timer, 150, 0);
apply = !ams_delta_muted && !cx81801_cmd_pending;
cx81801_cmd_pending = 1;
spin_unlock_bh(&ams_delta_lock);
* Arjan van de Ven <[email protected]> wrote:
> Subject: timer: add a mod_timer_msec() API function
> From: Arjan van de Ven <[email protected]>
>
> There is a common pattern in the kernel, where the caller wants
> to set a timer a specified number of milliseconds into the future.
>
> The typical solution then ends up
>
> mod_timer(&timer, jiffies + msecs_to_jiffies(msec_amount));
>
> or
>
> mod_timer(&timer, jiffies + HZ/some_value);
>
> This patch aims to simplify this pattern for the caller, and at
> the same time, make for a more power-friendly API.
>
> The new pattern for identical behavior will be
>
> mod_timer_msec(&timer, msec_amount, 0);
>
> while
>
> mod_timer_msec(&time, msec_amount, 100);
>
> would give the kernel 100 milliseconds of slack to find a power
> friendly time to group timers into one CPU wakeup.
>
> A patch to convert a number of users, to show how the API is used,
> will be sent as reply to this email.
the basic API idea looks good to me. A few comments:
> Signed-off-by: Arjan van de Ven <[email protected]>
>
> diff --git a/include/linux/timer.h b/include/linux/timer.h
> index a2d1eb6..006d4da 100644
> --- a/include/linux/timer.h
> +++ b/include/linux/timer.h
> @@ -162,6 +162,7 @@ static inline int timer_pending(const struct timer_list * timer)
> extern void add_timer_on(struct timer_list *timer, int cpu);
> extern int del_timer(struct timer_list * timer);
> extern int mod_timer(struct timer_list *timer, unsigned long expires);
> +extern int mod_timer_msec(struct timer_list *timer, unsigned long delay_ms, unsigned long slack_ms);
> extern int mod_timer_pending(struct timer_list *timer, unsigned long expires);
> extern int mod_timer_pinned(struct timer_list *timer, unsigned long expires);
>
> diff --git a/kernel/timer.c b/kernel/timer.c
> index 5db5a8d..c9d5cbf 100644
> --- a/kernel/timer.c
> +++ b/kernel/timer.c
> @@ -751,6 +751,47 @@ int mod_timer(struct timer_list *timer, unsigned long expires)
> EXPORT_SYMBOL(mod_timer);
>
> /**
> + * mod_timer_msec - modify a timer's timeout, using relative milliseconds
> + * @timer: the timer to be modified
> + * @delay_ms: the desired minimum delay in milliseconds
> + * @slack_ms: the amount of slack is ok in firing the timer
> + *
> + * Changes the timeout of a timer similar to mod_timer().
> + *
> + * mod_timer_msec() takes relative milliseconds rather than absolute
> + * jiffies as argument and also takes a "slack" amount, which is
> + * an explicit permission to treat the time of the timer as less
> + * precise in order to allow grouping of timers.
> + *
> + * The function returns whether it has modified a pending timer or not.
> + * (ie. mod_timer() of an inactive timer returns 0, mod_timer() of an
> + * active timer returns 1.)
> + */
> +int mod_timer_msec(struct timer_list *timer, unsigned long delay_ms, unsigned long slack_ms)
> +{
> + unsigned long next_jiffies, max_jiffies;
> + unsigned long rounded_jiffies;
> +
> + next_jiffies = jiffies + msecs_to_jiffies(delay_ms);
> + max_jiffies = jiffies + msecs_to_jiffies(delay_ms + slack_ms);
> + rounded_jiffies = round_jiffies(next_jiffies);
> +
> + /* check if rounding up next_jiffies is within the max */
> + if (rounded_jiffies <= max_jiffies && rounded_jiffies >= next_jiffies) {
> + next_jiffies = rounded_jiffies;
Is this comparison jiffies wraparound safe?
> + } else {
> + /* regular rounding failed; try a rounding to multiple-of-16 */
> + rounded_jiffies = (next_jiffies + 15) & ~0xF;
> + if (rounded_jiffies <= max_jiffies)
> + next_jiffies = rounded_jiffies;
> + }
> +
> + return mod_timer(timer, next_jiffies);
> +}
> +EXPORT_SYMBOL_GPL(mod_timer_msec);
This code first rounds to 1 second - and if that doesnt fall within the
slack window it rounds to the (rather aribtrary) rounding of 16 jiffies.
I'd suggest to use up the slack to its maximum, by rounding up modulo
the largest power-of-2 value that still fits into the slack.
So if slack is 30, the rounding is 16. If slack is 5, the rounding is 4,
etc.
Ingo
On Mon, 23 Nov 2009 09:26:48 +0100
Ingo Molnar <[email protected]> wrote:
>
> This code first rounds to 1 second - and if that doesnt fall within
> the slack window it rounds to the (rather aribtrary) rounding of 16
> jiffies.
>
> I'd suggest to use up the slack to its maximum, by rounding up modulo
> the largest power-of-2 value that still fits into the slack.
>
> So if slack is 30, the rounding is 16. If slack is 5, the rounding is
> 4, etc.
well.. the point of the rounding is that there is a maximum likelyhood
that OTHER timers align.
I suppose what you suggest would do that too; need to think of a clever
way to not make that expensive
(after coffee I'll look at if xor + find first bit will work ;-)
>
> Ingo
--
Arjan van de Ven Intel Open Source Technology Centre
For development, discussion and tips for power savings,
visit http://www.lesswatts.org
On Mon, 23 Nov 2009, Arjan van de Ven wrote:
> On Mon, 23 Nov 2009 09:26:48 +0100
> Ingo Molnar <[email protected]> wrote:
> >
> > This code first rounds to 1 second - and if that doesnt fall within
> > the slack window it rounds to the (rather aribtrary) rounding of 16
> > jiffies.
> >
> > I'd suggest to use up the slack to its maximum, by rounding up modulo
> > the largest power-of-2 value that still fits into the slack.
> >
> > So if slack is 30, the rounding is 16. If slack is 5, the rounding is
> > 4, etc.
>
> well.. the point of the rounding is that there is a maximum likelyhood
> that OTHER timers align.
>
> I suppose what you suggest would do that too; need to think of a clever
> way to not make that expensive
> (after coffee I'll look at if xor + find first bit will work ;-)
I think we need to rethink the timer wheel subsystem in general
instead of adding more and more fancy interfaces.
Looking at the examples you provided for mod_timer_msec() I noticed
that most of the slack values you chose are between 10% and 20% of the
timeout.
That means the larger the timeout the less interesting is the accuracy
which makes a lot of sense.
I really wonder whether there is any timer_list user which has the
need for large and precise timeouts. If not we could simplify the
whole timer wheel business radically and get rid of the worst thing in
it: recascading.
That's what I have in mind:
timeout accuracy
array0 < 0.256 s 1 ms
array1 < 2.560 s 40 ms
array2 < 25.600 s 400 ms
array3 < 256.000 s 4000 ms
array4 >= 256.000 s 40000 ms
Similar to the current timer wheel, but instead of recascading on
every wraparound of the array0 index we could expire the timers in
array1-4 in their accuracy interval which aligns them automatically
without any slack and rounding business on timer insertion.
The exact array definitions need of course more thought, but you get
the idea.
Such an implementation would also simplify the search for the next
expiring timer as we could keep track of empty/non-empty buckets with
an additional per array bitfield.
If there are a few timers which really need large and precise timeouts
its easy enough to switch them over to hrtimers.
Thoughts ?
Thanks,
tglx
> If there are a few timers which really need large and precise timeouts
> its easy enough to switch them over to hrtimers.
>
> Thoughts ?
Seems good to me - also fits with the long term need to push the core
timer handling into the hypervisor when running lots of VMs as it will
make it easy to keep all the VM timers lined up with each other