Commit 0a2c0f56 authored by Tejun Heo's avatar Tejun Heo Committed by Jeff Garzik
Browse files

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: default avatarTejun Heo <htejun@gmail.com>
Signed-off-by: default avatarJeff Garzik <jgarzik@redhat.com>
parent 341c2c95

drivers/ata/libata-eh.c

+20 −18
Original line number Diff line number Diff line
@@ -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 @@ dev_fail: 
		}

	}



	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)

drivers/ata/libata-pmp.c

+0 −10
Original line number Diff line number Diff line
@@ -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;

	}

include/linux/libata.h

+2 −0
Original line number Diff line number Diff line
@@ -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

CRA Git | Maintained and supported by SUSTech CRA and CCSE