On 08/05/2012 10:08 PM, Maya Erez wrote:
> When the mmcqd thread is idle, a delayed work is created to check the
> need for BKOPs. The time to start the delayed work is calculated based
> on the host controller suspend timeout, in case it was set. If not, a
> default time is used.
> If BKOPs is required in level 1, which is non-blocking, there will be
> polling of the card status to wait for the BKOPs completion and prevent
> suspend that will interrupt the BKOPs.
> If the card raised an exception, the need for urgent BKOPs (level 2/3)
> will be checked immediately and if needed, the BKOPs will be performed
> without waiting for the next idle time.
>
> Signed-off-by: Maya Erez <me...@codeaurora.org>
> Signed-off-by: Jaehoon Chung <jh80.ch...@samsung.com>
> ---
> This patch depends on the following patch:
> [PATCH v11] mmc: support BKOPS feature for eMMC
>
> This patch is based on the periodic BKOPs implementation in version 8 of
> "support BKOPS feature for eMMC" patch.
> The patch was modified to answer the following issues:
> - In order to prevent a race condition between going into suspend and
> starting BKOPs,
> the suspend timeout of the host controller is taking into accound in
> determination of the start time
> of the delayed work
> - Since mmc_start_bkops is called from two contexts now, mmc_claim_host was
> moved to the beginning of the function
> - Also, the check of doing_bkops should be protected when determing if an HPI
> is needed due to the same reason.
> - Starting and canceling the delayed work in each idle caused degradation of
> iozone performance. Therefore,
> the delayed work is not started on each idle. Currently the number of
> issued requests from the last delayed work
> is the trigger. We still investigate the best trigger for starting the
> delayed work.
> - To prevent degaradtion of iozone performance we also moved the call to
> mmc_claim_host outside of mmc_stop_bkops
> and its release is done after issue_fn. This prevents an addition of a full
> claim and release, that is also done
> in issue_fn for the first request after idle time.
> ---
> drivers/mmc/card/block.c | 3 +
> drivers/mmc/card/queue.c | 20 +++++
> drivers/mmc/core/core.c | 188
> +++++++++++++++++++++++++++++++++++++++++++---
> drivers/mmc/core/host.c | 24 ++++++
> include/linux/mmc/card.h | 3 +
> include/linux/mmc/core.h | 3 +
> include/linux/mmc/host.h | 25 ++++++
> 7 files changed, 256 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
> index f1c84de..4519271 100644
> --- a/drivers/mmc/card/block.c
> +++ b/drivers/mmc/card/block.c
> @@ -1268,6 +1268,9 @@ static int mmc_blk_issue_rw_rq(struct mmc_queue *mq,
> struct request *rqc)
> if (!rqc && !mq->mqrq_prev->req)
> return 0;
>
> + if (rqc)
> + card->idle_bkops_rw_reqs_nr++;
> +
> do {
> if (rqc) {
> /*
> diff --git a/drivers/mmc/card/queue.c b/drivers/mmc/card/queue.c
> index e360a97..c9e1cee 100644
> --- a/drivers/mmc/card/queue.c
> +++ b/drivers/mmc/card/queue.c
> @@ -51,6 +51,7 @@ static int mmc_queue_thread(void *d)
> {
> struct mmc_queue *mq = d;
> struct request_queue *q = mq->queue;
> + bool release_host = false;
>
> current->flags |= PF_MEMALLOC;
>
> @@ -66,13 +67,32 @@ static int mmc_queue_thread(void *d)
> spin_unlock_irq(q->queue_lock);
>
> if (req || mq->mqrq_prev->req) {
> + /*
> + * If this is the first request, BKOPs might be in
> + * progress and needs to be stopped before issuing the
> + * request
> + * */
> + if (!mq->mqrq_prev->req &&
> + mq->card->ext_csd.bkops_en &&
> + mq->card->idle_bkops_rw_reqs_nr == 0) {
> + release_host = true;
> + mmc_claim_host(mq->card->host);
> + mmc_stop_bkops(mq->card);
> + }
> +
> set_current_state(TASK_RUNNING);
> mq->issue_fn(mq, req);
> + if (release_host) {
> + release_host = false;
> + mmc_release_host(mq->card->host);
> + }
> } else {
> if (kthread_should_stop()) {
> set_current_state(TASK_RUNNING);
> break;
> }
> +
> + mmc_start_delayed_bkops(mq->card);
> up(&mq->thread_sem);
> schedule();
> down(&mq->thread_sem);
> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
> index ed2cc93..14830d4 100644
> --- a/drivers/mmc/core/core.c
> +++ b/drivers/mmc/core/core.c
> @@ -46,6 +46,15 @@
> * operations the card has to perform
> */
> #define MMC_BKOPS_MAX_TIMEOUT (4 * 60 * 1000) /* max time to wait in
> ms */
> +/* Polling timeout and interval for waiting on non-blocking BKOPs completion
> */
> +#define BKOPS_COMPLETION_POLLING_TIMEOUT 10000 /* in ms */
> +#define BKOPS_COMPLETION_POLLING_INTERVAL 1000 /* in ms */
> +/*
> + * Since canceling the delayed work might have significant effect on the
> + * performance of small requests we won't queue the delayed work every time
> + * mmcqd thread is idle
> + */
> +#define BKOPS_MIN_REQS_TO_QUEUE_DELAYED_WORK 1000
How did you get the minimum request number "1000"?
Is this tunable value?
>
> static struct workqueue_struct *workqueue;
> static const unsigned freqs[] = { 400000, 300000, 200000, 100000 };
> @@ -252,6 +261,37 @@ mmc_start_request(struct mmc_host *host, struct
> mmc_request *mrq)
> }
>
> /**
> + * mmc_start_delayed_bkops() - Start a delayed work to check for the
> need
> + * of non urgent BKOPs
> + *
> + * @card: MMC card to start BKOPS
> + */
> +void mmc_start_delayed_bkops(struct mmc_card *card)
> +{
> + if (!card->ext_csd.bkops_en || mmc_card_doing_bkops(card))
> + return;
if mmc_card_doing_bkops or didn't support bkops, idle_bkops_rw_reqs_nr need to
reset?
> +
> + if (card->idle_bkops_rw_reqs_nr < BKOPS_MIN_REQS_TO_QUEUE_DELAYED_WORK)
> + return;
> +
> + pr_debug("%s: %s: queueing delayed_bkops_work", __func__,
> + mmc_hostname(card->host));
missed "\n"..almost missed the new line("\n") at pr_debug.
> +
> + card->idle_bkops_rw_reqs_nr = 0;
> +
> + /*
> + * cancel_delayed_bkops_work will prevent a race condition between
> + * fetching a request by the queue_thread and the delayed work
> + */
> + card->host->bkops_info.cancel_delayed_work = false;
> + queue_delayed_work(card->host->bkops_info. wq,
> + &card->host->bkops_info.idle_time_dw,
> + msecs_to_jiffies(
> + card->host->bkops_info.time_to_start_bkops_ms));
> +}
> +EXPORT_SYMBOL(mmc_start_delayed_bkops);
> +
> +/**
> * mmc_start_bkops - start BKOPS for supported cards
> * @card: MMC card to start BKOPS
> * @form_exception: A flags to indicate if this function was
> @@ -268,23 +308,47 @@ void mmc_start_bkops(struct mmc_card *card, bool
> from_exception)
> bool use_busy_signal;
>
> BUG_ON(!card);
> -
> - if (!card->ext_csd.bkops_en || mmc_card_doing_bkops(card))
> + if (!card->ext_csd.bkops_en)
> return;
>
> + mmc_claim_host(card->host);
> +
> + if ((card->host->bkops_info.cancel_delayed_work) && !from_exception) {
> + pr_debug("%s: %s: cancel_delayed_work was set, exit",
> + __func__, mmc_hostname(card->host));
> + card->host->bkops_info.cancel_delayed_work = false;
> + goto out;
> + }
> +
> + if (mmc_card_doing_bkops(card)) {
> + pr_debug("%s: %s: already doing bkops, exit", __func__,
> + mmc_hostname(card->host));
> + goto out;
> + }
> +
> err = mmc_read_bkops_status(card);
> if (err) {
> - pr_err("%s: Didn't read bkops status : %d\n",
> + pr_err("%s: Error %d while reading bkops status\n",
> mmc_hostname(card->host), err);
> - return;
> + goto out;
> }
> -
> if (!card->ext_csd.raw_bkops_status)
> - return;
> + goto out;
>
> - if (card->ext_csd.raw_bkops_status < EXT_CSD_BKOPS_LEVEL_2
> - && (from_exception))
> - return;
> + pr_info("%s: %s: card->ext_csd.raw_bkops_status = %d", __func__,
> + mmc_hostname(card->host), card->ext_csd.raw_bkops_status);
> +
> + /*
> + * If the function was called due to exception but there is no need
> + * for urgent BKOPs, BKOPs will be performed by the delayed BKOPs
> + * work, before going to suspend
> + */
> + if ((card->ext_csd.raw_bkops_status < EXT_CSD_BKOPS_LEVEL_2)
> + && (from_exception)) {
> + pr_debug("%s: %s: Level 1 from exception, exit", __func__,
> + mmc_hostname(card->host));
> + goto out;
> + }
>
> mmc_claim_host(card->host);
> if (card->ext_csd.raw_bkops_status >= EXT_CSD_BKOPS_LEVEL_2) {
> @@ -308,13 +372,101 @@ void mmc_start_bkops(struct mmc_card *card, bool
> from_exception)
> * bkops executed synchronously, otherwise
> * the operation is in progress
> */
> - if (!use_busy_signal)
> + if (!use_busy_signal) {
> mmc_card_set_doing_bkops(card);
> + pr_debug("%s: %s: starting the polling thread", __func__,
> + mmc_hostname(card->host));
> + card->host->bkops_info.exit_wait_on_completion = false;
> + queue_work(system_nrt_wq,
> + &card->host->bkops_info.completion_polling);
> + }
> out:
> mmc_release_host(card->host);
> +
> }
> EXPORT_SYMBOL(mmc_start_bkops);
>
> +/**
> + * mmc_bkops_completion_polling() - Poll on the card status to
> + * wait for the non-blocking BKOPs completion
> + * @work: The completion polling work
> + *
> + * The on-going reading of the card status will prevent the card
> + * from getting into suspend while it is in the middle of
> + * performing BKOPs.
> + * Since the non blocking BKOPs can be interrupted by a fetched
> + * request we also check exit_wait_on_completion.
> + */
> +void mmc_bkops_completion_polling(struct work_struct *work)
> +{
> + struct mmc_host *host = container_of(work, struct mmc_host,
> + bkops_info.completion_polling);
> + unsigned long timeout_jiffies = jiffies +
> + msecs_to_jiffies(BKOPS_COMPLETION_POLLING_TIMEOUT);
> + u32 status;
> + int err;
> +
> + /*
> + * Wait for the BKOPs to complete. Keep reading the status to prevent
> + * the host from getting into suspend
> + */
> + do {
> + mmc_claim_host(host);
> +
> + if (host->bkops_info.exit_wait_on_completion ||
> + (!mmc_card_doing_bkops(host->card))) {
> + goto out;
> + }
> +
> + err = mmc_send_status(host->card, &status);
> + if (err) {
> + pr_err("%s: error %d requesting status\n",
> + mmc_hostname(host), err);
> + goto out;
> + }
> +
> + /*
> + * Some cards mishandle the status bits, so make sure to check
> + * both the busy indication and the card state.
> + */
> + if ((status & R1_READY_FOR_DATA) &&
> + (R1_CURRENT_STATE(status) != R1_STATE_PRG)) {
> + pr_debug("%s: completed BKOPs, exit polling", __func__);
missing "..\n". other pr_debug also missed.
> + mmc_card_clr_doing_bkops(host->card);
> + goto out;
> + }
> +
> + mmc_release_host(host);
> +
> + /*
> + * Sleep before checking the card status again to allow the
> + * card to complete the BKOPs operation
> + */
> + msleep(BKOPS_COMPLETION_POLLING_INTERVAL);
> + } while (time_before(jiffies, timeout_jiffies));
> +
> + pr_debug("%s: exit polling due to timeout", __func__);
> +
> + return;
> +out:
> + mmc_release_host(host);
> +}
> +
> +/**
> + * mmc_start_idle_time_bkops() - check if a non urgent BKOPs is
> + * needed
> + * @work: The idle time BKOPs work
> + */
> +void mmc_start_idle_time_bkops(struct work_struct *work)
> +{
> + struct mmc_host *host = container_of(work, struct mmc_host,
> + bkops_info.idle_time_dw.work);
> +
> + mmc_start_bkops(host->card, false);
> +
> +}
> +EXPORT_SYMBOL(mmc_start_idle_time_bkops);
> +
> static void mmc_wait_done(struct mmc_request *mrq)
> {
> complete(&mrq->completion);
> @@ -574,12 +726,28 @@ EXPORT_SYMBOL(mmc_wait_for_cmd);
> * to allow rapid servicing of foreground operations,e.g. read/
> * writes. Wait until the card comes out of the programming state
> * to avoid errors in servicing read/write requests.
> + *
> + * This function should be called when the host is claimed
> */
> int mmc_stop_bkops(struct mmc_card *card)
> {
> int err = 0;
>
> BUG_ON(!card);
> +
> + if (delayed_work_pending(&card->host->bkops_info.idle_time_dw))
> + cancel_delayed_work_sync(&card->host->bkops_info.idle_time_dw);
> +
> + /*
> + * Notify the delayed work to be cancelled, in case it was already
> + * removed from the queue, but was not started yet
> + */
> + card->host->bkops_info.cancel_delayed_work = true;
> +
> + if (!mmc_card_doing_bkops(card))
> + return err;
> +
> + card->host->bkops_info.exit_wait_on_completion = true;
> err = mmc_interrupt_hpi(card);
>
> /*
> diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
> index 597f189..d328191 100644
> --- a/drivers/mmc/core/host.c
> +++ b/drivers/mmc/core/host.c
> @@ -27,6 +27,11 @@
> #include "core.h"
> #include "host.h"
>
> +/*
> + * A default time for checking the need for non urgent BKOPs once MMC thread
> + * is idle.
> + */
> +#define MMC_IDLE_BKOPS_TIME_MS 2000
> #define cls_dev_to_mmc_host(d) container_of(d, struct mmc_host,
> class_dev)
>
> static void mmc_host_classdev_release(struct device *dev)
> @@ -336,6 +341,11 @@ struct mmc_host *mmc_alloc_host(int extra, struct device
> *dev)
> spin_lock_init(&host->lock);
> init_waitqueue_head(&host->wq);
> INIT_DELAYED_WORK(&host->detect, mmc_rescan);
> + host->bkops_info. wq = create_singlethread_workqueue("bkops_wq");
> + INIT_DELAYED_WORK(&host->bkops_info.idle_time_dw,
> + mmc_start_idle_time_bkops);
> + INIT_WORK(&host->bkops_info.completion_polling,
> + mmc_bkops_completion_polling);
> #ifdef CONFIG_PM
> host->pm_notify.notifier_call = mmc_pm_notify;
> #endif
> @@ -386,6 +396,20 @@ int mmc_add_host(struct mmc_host *host)
> #endif
> mmc_host_clk_sysfs_init(host);
>
> + /*
> + * Calculate the time to start the BKOPs checking.
> + * The idle time of the host controller should be taken into account
> + * in order to prevent a race condition before starting BKOPs and
> + * going into suspend.
> + * If the host controller didn't set its idle time, a default value is
> + * used.
> + */
> + host->bkops_info.time_to_start_bkops_ms = MMC_IDLE_BKOPS_TIME_MS;
> + if (host->bkops_info.host_suspend_tout_ms)
> + host->bkops_info.time_to_start_bkops_ms = min(
> + host->bkops_info.time_to_start_bkops_ms,
> + host->bkops_info.host_suspend_tout_ms/2);
> +
> mmc_start_host(host);
> register_pm_notifier(&host->pm_notify);
>
> diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
> index 342fe84..835d6c8 100644
> --- a/include/linux/mmc/card.h
> +++ b/include/linux/mmc/card.h
> @@ -280,6 +280,9 @@ struct mmc_card {
> struct dentry *debugfs_root;
> struct mmc_part part[MMC_NUM_PHY_PARTITION]; /* physical partitions */
> unsigned int nr_parts;
> +
> + /* num of read/write reqs since last BKOPs delayed work was queued */
> + unsigned int idle_bkops_rw_reqs_nr;
> };
>
> /*
> diff --git a/include/linux/mmc/core.h b/include/linux/mmc/core.h
> index 9b9cdaf..665d345 100644
> --- a/include/linux/mmc/core.h
> +++ b/include/linux/mmc/core.h
> @@ -145,6 +145,9 @@ extern int mmc_app_cmd(struct mmc_host *, struct mmc_card
> *);
> extern int mmc_wait_for_app_cmd(struct mmc_host *, struct mmc_card *,
> struct mmc_command *, int);
> extern void mmc_start_bkops(struct mmc_card *card, bool from_exception);
> +extern void mmc_start_delayed_bkops(struct mmc_card *card);
> +extern void mmc_start_idle_time_bkops(struct work_struct *work);
> +extern void mmc_bkops_completion_polling(struct work_struct *work);
> extern int __mmc_switch(struct mmc_card *, u8, u8, u8, unsigned int, bool);
> extern int mmc_switch(struct mmc_card *, u8, u8, u8, unsigned int);
>
> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
> index f578a71..8aaaf1d 100644
> --- a/include/linux/mmc/host.h
> +++ b/include/linux/mmc/host.h
> @@ -176,6 +176,29 @@ struct mmc_supply {
> struct regulator *vqmmc; /* Optional Vccq supply */
> };
>
> +/**
> + * struct mmc_bkops_info - BKOPs data
> + * @wq: workqueue
> + * @idle_time_dw: Idle time bkops delayed work
> + * @host_suspend_tout_ms: The host controller idle time,
> + * before getting into suspend
> + * @time_to_start_bkops_ms: The time to start the BKOPs
> + * delayed work once MMC thread is idle
> + * @completion_polling: Poll on BKOPs completion
> + * @cancel_delayed_work: A flag to indicate if the delayed work
> + * should be cancelled
> + * @exit_wait_on_completion: Exit flag for non blocking BKOPs
> + */
> +struct mmc_bkops_info {
> + struct workqueue_struct *wq;
> + struct delayed_work idle_time_dw;
> + unsigned int host_suspend_tout_ms;
> + unsigned int time_to_start_bkops_ms;
> + struct work_struct completion_polling;
> + bool cancel_delayed_work;
> + bool exit_wait_on_completion;
> +};
> +
> struct mmc_host {
> struct device *parent;
> struct device class_dev;
> @@ -340,6 +363,8 @@ struct mmc_host {
>
> unsigned int actual_clock; /* Actual HC clock rate */
>
> + struct mmc_bkops_info bkops_info;
> +
> unsigned long private[0] ____cacheline_aligned;
> };
>
>
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