Hi Konstantin, I'm looking into this patch. Idea looks good as a whole.
On Tuesday, November 13, 2012, Konstantin Dorfman <[email protected]> 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]> > --- > 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 > > diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c > index 172a768..34d8bd9 100644 > --- a/drivers/mmc/card/block.c > +++ b/drivers/mmc/card/block.c > @@ -112,17 +112,6 @@ 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"); > > @@ -1225,6 +1214,7 @@ static void mmc_blk_rw_rq_prep(struct mmc_queue_req > *mqrq, > > mqrq->mmc_active.mrq = &brq->mrq; > mqrq->mmc_active.err_check = mmc_blk_err_check; > + mqrq->mmc_active.mrq->context_info = &mq->context_info; > > mmc_queue_bounce_pre(mqrq); > } > @@ -1284,9 +1274,12 @@ 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; > @@ -1295,6 +1288,8 @@ 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 */ > case MMC_BLK_SUCCESS: > case MMC_BLK_PARTIAL: > /* > @@ -1367,7 +1362,8 @@ static int mmc_blk_issue_rw_rq(struct mmc_queue *mq, > struct request *rqc) > * prepare it again and resend. > */ > mmc_blk_rw_rq_prep(mq_rq, card, disable_multi, mq); > - mmc_start_req(card->host, &mq_rq->mmc_active, NULL); > + mmc_start_req(card->host, &mq_rq->mmc_active, > + (int *)&status); Here, we'll try to send previous request which is not completed successfully. And then at the top of do~while, mmc_start_req will be called for current request and get the status. Above change looks like unnecessary. Is there any reason? Thanks, Seungwon Jeon > } > } while (ret); > > @@ -1407,6 +1403,8 @@ 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) > @@ -1426,9 +1424,10 @@ 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..ef575ac 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->context_info.is_waiting_last_req = true; > + } > 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 +111,7 @@ static void mmc_request_fn(struct request_queue *q) > { > struct mmc_queue *mq = q->queuedata; > struct request *req; > + unsigned long flags; > > if (!mq) { > while ((req = blk_fetch_request(q)) != NULL) { > @@ -111,8 +120,19 @@ static void mmc_request_fn(struct request_queue *q) > } > return; > } > - > - if (!mq->mqrq_cur->req && !mq->mqrq_prev->req) > + 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(&mq->context_info.lock, flags); > + if (mq->context_info.is_waiting_last_req) { > + mq->context_info.is_new_req = true; > + wake_up_interruptible(&mq->context_info.wait); > + } > + spin_unlock_irqrestore(&mq->context_info.lock, flags); > + } else if (!mq->mqrq_cur->req && !mq->mqrq_prev->req) > wake_up_process(mq->thread); > } > > @@ -262,6 +282,11 @@ int mmc_init_queue(struct mmc_queue *mq, struct mmc_card > *card, > } > > sema_init(&mq->thread_sem, 1); > + spin_lock_init(&mq->context_info.lock); > + mq->context_info.is_new_req = false; > + mq->context_info.is_done_rcv = false; > + mq->context_info.is_waiting_last_req = false; > + init_waitqueue_head(&mq->context_info.wait); > > mq->thread = kthread_run(mmc_queue_thread, mq, "mmcqd/%d%s", > host->index, subname ? subname : ""); > diff --git a/drivers/mmc/card/queue.h b/drivers/mmc/card/queue.h > index d2a1eb4..f5885e9 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; > @@ -33,6 +35,7 @@ struct mmc_queue { > struct mmc_queue_req mqrq[2]; > struct mmc_queue_req *mqrq_cur; > struct mmc_queue_req *mqrq_prev; > + struct mmc_context_info context_info; > }; > > extern int mmc_init_queue(struct mmc_queue *, struct mmc_card *, spinlock_t > *, > diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c > index 06c42cf..3374195 100644 > --- a/drivers/mmc/core/core.c > +++ b/drivers/mmc/core/core.c > @@ -316,11 +316,43 @@ 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->context_info->is_done_rcv = true; > + wake_up_interruptible(&mrq->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); > @@ -334,6 +366,60 @@ 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 = mrq->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) > { > @@ -396,23 +482,17 @@ static void mmc_post_req(struct mmc_host *host, struct > mmc_request *mrq, > } > > /** > - * mmc_start_req - start a non-blocking request > - * @host: MMC host to start command > - * @areq: async request to start > - * @error: out parameter returns 0 for success, otherwise non zero > - * > - * Start a new MMC custom command request for a host. > - * If there is on ongoing async request wait for completion > - * of that request and start the new one and return. > - * Does not wait for the new request to complete. > + * mmc_start_req - start a non-blocking data request > + * @host: MMC host to start the command > + * @areq: async request to start > + * @error: out parameter; returns 0 for success, otherwise non zero > * > - * Returns the completed request, NULL in case of none completed. > - * Wait for the an ongoing request (previoulsy started) to complete and > - * return the completed request. If there is no ongoing request, NULL > - * is returned without waiting. NULL is not an error condition. > + * Wait for the ongoing request (previoulsy started) to complete and > + * return the completed request. If there is no ongoing request, NULL > + * is returned without waiting. NULL is not an error condition. > */ > struct mmc_async_req *mmc_start_req(struct mmc_host *host, > - struct mmc_async_req *areq, int *error) > + struct mmc_async_req *areq, int *error) > { > int err = 0; > int start_err = 0; > @@ -423,8 +503,20 @@ 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(); > + } > + *error = err; > + /* > + * The previous request was not completed, > + * nothing to return > + */ > + return NULL; > + } > /* > * Check BKOPS urgency for each R1 response > */ > @@ -436,7 +528,7 @@ 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); > @@ -452,6 +544,7 @@ struct mmc_async_req *mmc_start_req(struct mmc_host *host, > > if (error) > *error = err; > + > return data; > } > EXPORT_SYMBOL(mmc_start_req); > diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h > index 943550d..9681d8f 100644 > --- a/include/linux/mmc/card.h > +++ b/include/linux/mmc/card.h > @@ -186,6 +186,18 @@ 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 9b9cdaf..aa17096 100644 > --- a/include/linux/mmc/core.h > +++ b/include/linux/mmc/core.h > @@ -120,6 +120,21 @@ struct mmc_data { > s32 host_cookie; /* host private data */ > }; > > +/** > + * 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_request { > struct mmc_command *sbc; /* SET_BLOCK_COUNT for > multiblock */ > struct mmc_command *cmd; > @@ -128,6 +143,7 @@ struct mmc_request { > > struct completion completion; > void (*done)(struct mmc_request *);/* completion > function */ > + struct mmc_context_info *context_info; > }; > > struct mmc_host; > -- > 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
