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libata: improve EH retry delay handling 

EH retries were delayed by 5 seconds to ensure that resets don't occur
back-to-back.  However, this 5 second delay is superflous or excessive
in many cases.  For example, after IDENTIFY times out, there's no
reason to wait five more seconds before retrying.

This patch adds ehc->last_reset timestamp and record the timestamp for
the last reset trial or success and uses it to space resets by
ATA_EH_RESET_COOL_DOWN which is 5 secs and removes unconditional 5 sec
sleeps.

As this change makes inter-try waits often shorter and they're
redundant in nature, this patch also removes the "retrying..."
messages.

While at it, convert explicit rounding up division to DIV_ROUND_UP().

This change speeds up EH in many cases w/o sacrificing robustness.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
This commit is contained in:
Tejun Heo 2008-05-20 02:17:52 +09:00 committed by Jeff Garzik
parent 341c2c958e
commit 0a2c0f5615
3 changed files with 22 additions and 28 deletions
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38
drivers/ata/libata-eh.c
View File

@ -67,6 +67,9 @@ enum {
ATA_ECAT_DUBIOUS_UNK_DEV = 7,
ATA_ECAT_NR = 8,
/* always put at least this amount of time between resets */
ATA_EH_RESET_COOL_DOWN = 5000,
/* Waiting in ->prereset can never be reliable. It's
* sometimes nice to wait there but it can't be depended upon;
* otherwise, we wouldn't be resetting. Just give it enough
@ -485,6 +488,9 @@ void ata_scsi_error(struct Scsi_Host *host)
if (ata_ncq_enabled(dev))
ehc->saved_ncq_enabled |= 1 << devno;
}
/* set last reset timestamp to some time in the past */
ehc->last_reset = jiffies - 60 * HZ;
}
ap->pflags |= ATA_PFLAG_EH_IN_PROGRESS;
@ -2088,11 +2094,17 @@ int ata_eh_reset(struct ata_link *link, int classify,
/*
* Prepare to reset
*/
now = jiffies;
deadline = ata_deadline(ehc->last_reset, ATA_EH_RESET_COOL_DOWN);
if (time_before(now, deadline))
schedule_timeout_uninterruptible(deadline - now);
spin_lock_irqsave(ap->lock, flags);
ap->pflags |= ATA_PFLAG_RESETTING;
spin_unlock_irqrestore(ap->lock, flags);
ata_eh_about_to_do(link, NULL, ATA_EH_RESET);
ehc->last_reset = jiffies;
ata_link_for_each_dev(dev, link) {
/* If we issue an SRST then an ATA drive (not ATAPI)
@ -2158,6 +2170,7 @@ int ata_eh_reset(struct ata_link *link, int classify,
/*
* Perform reset
*/
ehc->last_reset = jiffies;
if (ata_is_host_link(link))
ata_eh_freeze_port(ap);
@ -2278,6 +2291,7 @@ int ata_eh_reset(struct ata_link *link, int classify,
/* reset successful, schedule revalidation */
ata_eh_done(link, NULL, ATA_EH_RESET);
ehc->last_reset = jiffies;
ehc->i.action |= ATA_EH_REVALIDATE;
rc = 0;
@ -2304,9 +2318,9 @@ int ata_eh_reset(struct ata_link *link, int classify,
if (time_before(now, deadline)) {
unsigned long delta = deadline - now;
ata_link_printk(link, KERN_WARNING, "reset failed "
"(errno=%d), retrying in %u secs\n",
rc, (jiffies_to_msecs(delta) + 999) / 1000);
ata_link_printk(link, KERN_WARNING,
"reset failed (errno=%d), retrying in %u secs\n",
rc, DIV_ROUND_UP(jiffies_to_msecs(delta), 1000));
while (delta)
delta = schedule_timeout_uninterruptible(delta);
@ -2623,7 +2637,7 @@ int ata_eh_recover(struct ata_port *ap, ata_prereset_fn_t prereset,
{
struct ata_link *link;
struct ata_device *dev;
int nr_failed_devs, nr_disabled_devs;
int nr_failed_devs;
int rc;
unsigned long flags;
@ -2666,7 +2680,6 @@ int ata_eh_recover(struct ata_port *ap, ata_prereset_fn_t prereset,
retry:
rc = 0;
nr_failed_devs = 0;
nr_disabled_devs = 0;
/* if UNLOADING, finish immediately */
if (ap->pflags & ATA_PFLAG_UNLOADING)
@ -2733,8 +2746,7 @@ int ata_eh_recover(struct ata_port *ap, ata_prereset_fn_t prereset,
dev_fail:
nr_failed_devs++;
if (ata_eh_handle_dev_fail(dev, rc))
nr_disabled_devs++;
ata_eh_handle_dev_fail(dev, rc);
if (ap->pflags & ATA_PFLAG_FROZEN) {
/* PMP reset requires working host port.
@ -2746,18 +2758,8 @@ int ata_eh_recover(struct ata_port *ap, ata_prereset_fn_t prereset,
}
}
if (nr_failed_devs) {
if (nr_failed_devs != nr_disabled_devs) {
ata_port_printk(ap, KERN_WARNING, "failed to recover "
"some devices, retrying in 5 secs\n");
ssleep(5);
} else {
/* no device left to recover, repeat fast */
msleep(500);
}
if (nr_failed_devs)
goto retry;
}
out:
if (rc && r_failed_link)

10
drivers/ata/libata-pmp.c
View File

@ -727,19 +727,12 @@ static int sata_pmp_eh_recover_pmp(struct ata_port *ap,
}
if (tries) {
int sleep = ehc->i.flags & ATA_EHI_DID_RESET;
/* consecutive revalidation failures? speed down */
if (reval_failed)
sata_down_spd_limit(link);
else
reval_failed = 1;
ata_dev_printk(dev, KERN_WARNING,
"retrying reset%s\n",
sleep ? " in 5 secs" : "");
if (sleep)
ssleep(5);
ehc->i.action |= ATA_EH_RESET;
goto retry;
} else {
@ -991,10 +984,7 @@ static int sata_pmp_eh_recover(struct ata_port *ap)
goto retry;
if (--pmp_tries) {
ata_port_printk(ap, KERN_WARNING,
"failed to recover PMP, retrying in 5 secs\n");
pmp_ehc->i.action |= ATA_EH_RESET;
ssleep(5);
goto retry;
}

2
include/linux/libata.h
View File

@ -602,6 +602,8 @@ struct ata_eh_context {
unsigned int did_probe_mask;
unsigned int saved_ncq_enabled;
u8 saved_xfer_mode[ATA_MAX_DEVICES];
/* timestamp for the last reset attempt or success */
unsigned long last_reset;
};
struct ata_acpi_drive