Hi, Konstantin. I added comments more below.
On Wednesday, December 12, 2012, Seungwon Jeon wrote: > On Monday, December 10, 2012, Konstantin Dorfman wrote: > > When current request is running on the bus and if next request fetched > > by mmcqd is NULL, mmc context (mmcqd thread) gets blocked until the > > current request completes. This means if new request comes in while > > the mmcqd thread is blocked, this new request can not be prepared in > > parallel to current ongoing request. This may result in latency to > > start new request. > > > > This change allows to wake up the MMC thread (which > > is waiting for the current running request to complete). Now once the > > MMC thread is woken up, new request can be fetched and prepared in > > parallel to current running request which means this new request can > > be started immediately after the current running request completes. > > > > With this change read throughput is improved by 16%. > > > > Signed-off-by: Konstantin Dorfman <[email protected]> > > --- > > > > > > v4: > > keeps new synchronization mechanism within mmc/core > > layer, so mmc/core external API's are not changed. > > - context_info moved into mmc_host struct > > - context_info initialized in mmc_rescan_try_freq() > > > > v3: > > - new MMC_QUEUE_NEW_REQUEST flag to mark new request case > > - lock added to update is_new_req flag > > - condition for sending new req notification changed > > - Moved start waiting for new req notification after fetching NULL > > v2: > > - Removed synchronization flags > > - removed lock from done() > > - flags names changed > > v1: > > - Initial submit > > > > drivers/mmc/card/block.c | 25 +++++------ > > drivers/mmc/card/queue.c | 27 ++++++++++- > > drivers/mmc/card/queue.h | 2 + > > drivers/mmc/core/core.c | 112 > > ++++++++++++++++++++++++++++++++++++++++++++- > > include/linux/mmc/card.h | 12 +++++ > > include/linux/mmc/core.h | 3 +- > > include/linux/mmc/host.h | 16 +++++++ > > 7 files changed, 177 insertions(+), 20 deletions(-) > > > > diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c > > index 21056b9..6fe0412 100644 > > --- a/drivers/mmc/card/block.c > > +++ b/drivers/mmc/card/block.c > > @@ -113,17 +113,6 @@ struct mmc_blk_data { > > > > static DEFINE_MUTEX(open_lock); > > > > -enum mmc_blk_status { > > - MMC_BLK_SUCCESS = 0, > > - MMC_BLK_PARTIAL, > > - MMC_BLK_CMD_ERR, > > - MMC_BLK_RETRY, > > - MMC_BLK_ABORT, > > - MMC_BLK_DATA_ERR, > > - MMC_BLK_ECC_ERR, > > - MMC_BLK_NOMEDIUM, > > -}; > > - > > module_param(perdev_minors, int, 0444); > > MODULE_PARM_DESC(perdev_minors, "Minors numbers to allocate per device"); > > > > @@ -1180,6 +1169,7 @@ static void mmc_blk_rw_rq_prep(struct mmc_queue_req > > *mqrq, > > memset(brq, 0, sizeof(struct mmc_blk_request)); > > brq->mrq.cmd = &brq->cmd; > > brq->mrq.data = &brq->data; > > + brq->mrq.host = card->host; > Above setting have been added at __mmc_start_data_req function in previous > sending. > Currently there is no setting for sdio. Considering sdio case, the former > would be better. > > > > > brq->cmd.arg = blk_rq_pos(req); > > if (!mmc_card_blockaddr(card)) > > @@ -1363,9 +1353,12 @@ static int mmc_blk_issue_rw_rq(struct mmc_queue *mq, > > struct request *rqc) > > areq = &mq->mqrq_cur->mmc_active; > > } else > > areq = NULL; > > - areq = mmc_start_req(card->host, areq, (int *) &status); > > - if (!areq) > > + areq = mmc_start_req(card->host, areq, (int *)&status); > > + if (!areq) { > > + if (status == MMC_BLK_NEW_REQUEST) > > + mq->flags |= MMC_QUEUE_NEW_REQUEST; > > return 0; > > + } > > > > mq_rq = container_of(areq, struct mmc_queue_req, mmc_active); > > brq = &mq_rq->brq; > > @@ -1374,6 +1367,8 @@ static int mmc_blk_issue_rw_rq(struct mmc_queue *mq, > > struct request *rqc) > > mmc_queue_bounce_post(mq_rq); > > > > switch (status) { > > + case MMC_BLK_NEW_REQUEST: > > + BUG(); /* should never get here */ Is there any case to reach here? I didn't find it. > > case MMC_BLK_SUCCESS: > > case MMC_BLK_PARTIAL: > > /* > > @@ -1486,6 +1481,7 @@ static int mmc_blk_issue_rq(struct mmc_queue *mq, > > struct request *req) > > goto out; > > } > > > > + mq->flags &= ~MMC_QUEUE_NEW_REQUEST; > > if (req && req->cmd_flags & REQ_DISCARD) { > > /* complete ongoing async transfer before issuing discard */ > > if (card->host->areq) > > @@ -1505,9 +1501,10 @@ static int mmc_blk_issue_rq(struct mmc_queue *mq, > > struct request *req) > > } > > > > out: > > - if (!req) > > + if (!req && !(mq->flags & MMC_QUEUE_NEW_REQUEST)) > > /* release host only when there are no more requests */ > > mmc_release_host(card->host); > > + > > return ret; > > } > > > > diff --git a/drivers/mmc/card/queue.c b/drivers/mmc/card/queue.c > > index fadf52e..0c37b49 100644 > > --- a/drivers/mmc/card/queue.c > > +++ b/drivers/mmc/card/queue.c > > @@ -22,7 +22,6 @@ > > > > #define MMC_QUEUE_BOUNCESZ 65536 > > > > -#define MMC_QUEUE_SUSPENDED (1 << 0) > > > > /* > > * Prepare a MMC request. This just filters out odd stuff. > > @@ -63,11 +62,20 @@ static int mmc_queue_thread(void *d) > > set_current_state(TASK_INTERRUPTIBLE); > > req = blk_fetch_request(q); > > mq->mqrq_cur->req = req; > > + if (!req && mq->mqrq_prev->req && > > + !(mq->mqrq_prev->req->cmd_flags & REQ_FLUSH) && > > + !(mq->mqrq_prev->req->cmd_flags & REQ_DISCARD)) > > + mq->card->host->context_info.is_waiting_last_req = true; > > + Unlike normal R/W request, request for discard/flush will be finished synchronously. That means blk_end_request is called with 1's cycle of 'issue_fn' and request will be freed in block layer. Currently 'mqrq_prev->req' is keeping these request and is used above condition. Maybe, same area may be reallocated for normal R/W request after discard/flush is finished. But we still expect discard or flush is saved in 'mq->mqrq_prev->req'. I wonder that 'mq->mqrq_prev->req' indicates the valid area in all case. Thanks, Seungwon Jeon > > spin_unlock_irq(q->queue_lock); > > > > if (req || mq->mqrq_prev->req) { > > set_current_state(TASK_RUNNING); > > mq->issue_fn(mq, req); > > + if (mq->flags & MMC_QUEUE_NEW_REQUEST) { > > + mq->flags &= ~MMC_QUEUE_NEW_REQUEST; > > + continue; /* fetch again */ > > + } > > > > /* > > * Current request becomes previous request > > @@ -103,6 +111,8 @@ static void mmc_request_fn(struct request_queue *q) > > { > > struct mmc_queue *mq = q->queuedata; > > struct request *req; > > + unsigned long flags; > > + struct mmc_context_info *cntx; > > > > if (!mq) { > > while ((req = blk_fetch_request(q)) != NULL) { > > @@ -112,7 +122,20 @@ static void mmc_request_fn(struct request_queue *q) > > return; > > } > > > > - if (!mq->mqrq_cur->req && !mq->mqrq_prev->req) > > + cntx = &mq->card->host->context_info; > > + if (!mq->mqrq_cur->req && mq->mqrq_prev->req) { > > + /* > > + * New MMC request arrived when MMC thread may be > > + * blocked on the previous request to be complete > > + * with no current request fetched > > + */ > > + spin_lock_irqsave(&cntx->lock, flags); > > + if (cntx->is_waiting_last_req) { > > + cntx->is_new_req = true; > > + wake_up_interruptible(&cntx->wait); > > + } > > + spin_unlock_irqrestore(&cntx->lock, flags); > > + } else if (!mq->mqrq_cur->req && !mq->mqrq_prev->req) > > wake_up_process(mq->thread); > > } > > > > diff --git a/drivers/mmc/card/queue.h b/drivers/mmc/card/queue.h > > index d2a1eb4..970d9e7 100644 > > --- a/drivers/mmc/card/queue.h > > +++ b/drivers/mmc/card/queue.h > > @@ -26,6 +26,8 @@ struct mmc_queue { > > struct mmc_card *card; > > struct task_struct *thread; > > struct semaphore thread_sem; > > +#define MMC_QUEUE_SUSPENDED (1 << 0) > > +#define MMC_QUEUE_NEW_REQUEST (1 << 1) > > unsigned int flags; > > int (*issue_fn)(struct mmc_queue *, struct request > > *); > > void *data; > > diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c > > index aaed768..344cd3a 100644 > > --- a/drivers/mmc/core/core.c > > +++ b/drivers/mmc/core/core.c > > @@ -319,11 +319,43 @@ out: > > } > > EXPORT_SYMBOL(mmc_start_bkops); > > > > +/* > > + * mmc_wait_data_done() - done callback for data request > > + * @mrq: done data request > > + * > > + * Wakes up mmc context, passed as callback to host controller driver > > + */ > > +static void mmc_wait_data_done(struct mmc_request *mrq) > > +{ > > + mrq->host->context_info.is_done_rcv = true; > > + wake_up_interruptible(&mrq->host->context_info.wait); > > +} > > + > > static void mmc_wait_done(struct mmc_request *mrq) > > { > > complete(&mrq->completion); > > } > > > > +/* > > + *__mmc_start_data_req() - starts data request > > + * @host: MMC host to start the request > > + * @mrq: data request to start > > + * > > + * Fills done callback that will be used when request are done by card. > > + * Starts data mmc request execution > > + */ > > +static int __mmc_start_data_req(struct mmc_host *host, struct mmc_request > > *mrq) > > +{ > > + mrq->done = mmc_wait_data_done; > > + if (mmc_card_removed(host->card)) { > > + mrq->cmd->error = -ENOMEDIUM; > > + return -ENOMEDIUM; > > + } > > + mmc_start_request(host, mrq); > > + > > + return 0; > > +} > > + > > static int __mmc_start_req(struct mmc_host *host, struct mmc_request *mrq) > > { > > init_completion(&mrq->completion); > > @@ -337,6 +369,60 @@ static int __mmc_start_req(struct mmc_host *host, > > struct mmc_request *mrq) > > return 0; > > } > > > > +/* > > + * mmc_wait_for_data_req_done() - wait for request completed or new > > + * request notification arrives > > + * @host: MMC host to prepare the command. > > + * @mrq: MMC request to wait for > > + * > > + * Blocks MMC context till host controller will ack end of data request > > + * execution or new request arrives from block layer. Handles > > + * command retries. > > + * > > + * Returns enum mmc_blk_status after checking errors. > > + */ > > +static int mmc_wait_for_data_req_done(struct mmc_host *host, > > + struct mmc_request *mrq) > > +{ > > + struct mmc_command *cmd; > > + struct mmc_context_info *context_info = &host->context_info; > > + int err; > > + unsigned long flags; > > + > > + while (1) { > > + wait_event_interruptible(context_info->wait, > > + (context_info->is_done_rcv || > > + context_info->is_new_req)); > > + spin_lock_irqsave(&context_info->lock, flags); > > + context_info->is_waiting_last_req = false; > > + spin_unlock_irqrestore(&context_info->lock, flags); > > + if (context_info->is_done_rcv) { > > + context_info->is_done_rcv = false; > > + context_info->is_new_req = false; > > + cmd = mrq->cmd; > > + if (!cmd->error || !cmd->retries || > > + mmc_card_removed(host->card)) { > > + err = host->areq->err_check(host->card, > > + host->areq); > > + break; /* return err */ > > + } else { > > + pr_info("%s: req failed (CMD%u): %d, > > retrying...\n", > > + mmc_hostname(host), > > + cmd->opcode, cmd->error); > > + cmd->retries--; > > + cmd->error = 0; > > + host->ops->request(host, mrq); > > + continue; /* wait for done/new event again */ > > + } > > + } else if (context_info->is_new_req) { > > + context_info->is_new_req = false; > > + err = MMC_BLK_NEW_REQUEST; > > + break; /* return err */ > > + } > > + } /* while */ > > + return err; > > +} > > + > > static void mmc_wait_for_req_done(struct mmc_host *host, > > struct mmc_request *mrq) > > { > > @@ -426,8 +512,21 @@ struct mmc_async_req *mmc_start_req(struct mmc_host > > *host, > > mmc_pre_req(host, areq->mrq, !host->areq); > > > > if (host->areq) { > > - mmc_wait_for_req_done(host, host->areq->mrq); > > - err = host->areq->err_check(host->card, host->areq); > > + err = mmc_wait_for_data_req_done(host, host->areq->mrq); > > + if (err == MMC_BLK_NEW_REQUEST) { > > + if (areq) { > > + pr_err("%s: new request while areq = %p", > > + mmc_hostname(host), areq); > > + BUG_ON(1); > > + } > > + if (error) > > + *error = err; > > + /* > > + * The previous request was not completed, > > + * nothing to return > > + */ > > + return NULL; > > + } > > /* > > * Check BKOPS urgency for each R1 response > > */ > > @@ -439,7 +538,7 @@ struct mmc_async_req *mmc_start_req(struct mmc_host > > *host, > > } > > > > if (!err && areq) > > - start_err = __mmc_start_req(host, areq->mrq); > > + start_err = __mmc_start_data_req(host, areq->mrq); > > > > if (host->areq) > > mmc_post_req(host, host->areq->mrq, 0); > > @@ -455,6 +554,7 @@ struct mmc_async_req *mmc_start_req(struct mmc_host > > *host, > > > > if (error) > > *error = err; > > + > > return data; > > } > > EXPORT_SYMBOL(mmc_start_req); > > @@ -2086,6 +2186,12 @@ static int mmc_rescan_try_freq(struct mmc_host > > *host, unsigned freq) > > > > mmc_send_if_cond(host, host->ocr_avail); > > > > + spin_lock_init(&host->context_info.lock); > > + host->context_info.is_new_req = false; > > + host->context_info.is_done_rcv = false; > > + host->context_info.is_waiting_last_req = false; > > + init_waitqueue_head(&host->context_info.wait); > > + > This path may be retired when mmc_rescan_try_freq is failed. > How about putting these in mmc_add_card(mmc/core/bus.c) > <Quote> > ret = device_add(&card->dev); > if (ret) > return ret; > -> Here seems good point. > > mmc_card_set_present(card); > </Quote> > Thanks, > Seungwon Jeon > > > /* Order's important: probe SDIO, then SD, then MMC */ > > if (!mmc_attach_sdio(host)) > > return 0; > > diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h > > index 5c69315..be2500a 100644 > > --- a/include/linux/mmc/card.h > > +++ b/include/linux/mmc/card.h > > @@ -187,6 +187,18 @@ struct sdio_func_tuple; > > > > #define SDIO_MAX_FUNCS 7 > > > > +enum mmc_blk_status { > > + MMC_BLK_SUCCESS = 0, > > + MMC_BLK_PARTIAL, > > + MMC_BLK_CMD_ERR, > > + MMC_BLK_RETRY, > > + MMC_BLK_ABORT, > > + MMC_BLK_DATA_ERR, > > + MMC_BLK_ECC_ERR, > > + MMC_BLK_NOMEDIUM, > > + MMC_BLK_NEW_REQUEST, > > +}; > > + > > /* The number of MMC physical partitions. These consist of: > > * boot partitions (2), general purpose partitions (4) in MMC v4.4. > > */ > > diff --git a/include/linux/mmc/core.h b/include/linux/mmc/core.h > > index 5bf7c22..724cc95 100644 > > --- a/include/linux/mmc/core.h > > +++ b/include/linux/mmc/core.h > > @@ -120,6 +120,7 @@ struct mmc_data { > > s32 host_cookie; /* host private data */ > > }; > > > > +struct mmc_host; > > struct mmc_request { > > struct mmc_command *sbc; /* SET_BLOCK_COUNT for > > multiblock */ > > struct mmc_command *cmd; > > @@ -128,9 +129,9 @@ struct mmc_request { > > > > struct completion completion; > > void (*done)(struct mmc_request *);/* completion > > function */ > > + struct mmc_host *host; > > }; > > > > -struct mmc_host; > > struct mmc_card; > > struct mmc_async_req; > > > > diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h > > index 61a10c1..c26c180 100644 > > --- a/include/linux/mmc/host.h > > +++ b/include/linux/mmc/host.h > > @@ -177,6 +177,21 @@ struct mmc_supply { > > struct regulator *vqmmc; /* Optional Vccq supply */ > > }; > > > > +/** > > + * mmc_context_info - synchronization details for mmc context > > + * @is_done_rcv wake up reason was done request > > + * @is_new_req wake up reason was new request > > + * @is_waiting_last_req mmc context waiting for single running request > > + * @wait wait queue > > + */ > > +struct mmc_context_info { > > + bool is_done_rcv; > > + bool is_new_req; > > + bool is_waiting_last_req; > > + wait_queue_head_t wait; > > + spinlock_t lock; > > +}; > > + > > struct mmc_host { > > struct device *parent; > > struct device class_dev; > > @@ -331,6 +346,7 @@ struct mmc_host { > > struct dentry *debugfs_root; > > > > struct mmc_async_req *areq; /* active async req */ > > + struct mmc_context_info context_info; /* async synchronization info */ > > > > #ifdef CONFIG_FAIL_MMC_REQUEST > > struct fault_attr fail_mmc_request; > > -- > > 1.7.6 > > -- > > Konstantin Dorfman, > > QUALCOMM ISRAEL, on behalf of Qualcomm Innovation Center, > > Inc. is a member of Code Aurora Forum, > > hosted by The Linux Foundation > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-mmc" in > > the body of a message to [email protected] > > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
