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linux_dsm_epyc7002/drivers/mmc/core/queue.c
Baolin Wang 511ce378e1 mmc: Add MMC host software queue support 
Now the MMC read/write stack will always wait for previous request is
completed by mmc_blk_rw_wait(), before sending a new request to hardware,
or queue a work to complete request, that will bring context switching
overhead and spend some extra time to poll the card for busy completion
for I/O writes via sending CMD13, especially for high I/O per second
rates, to affect the IO performance.

Thus this patch introduces MMC software queue interface based on the
hardware command queue engine's interfaces, which is similar with the
hardware command queue engine's idea, that can remove the context
switching. Moreover we set the default queue depth as 64 for software
queue, which allows more requests to be prepared, merged and inserted
into IO scheduler to improve performance, but we only allow 2 requests
in flight, that is enough to let the irq handler always trigger the
next request without a context switch, as well as avoiding a long latency.

Moreover the host controller should support HW busy detection for I/O
operations when enabling the host software queue. That means, the host
controller must not complete a data transfer request, until after the
card stops signals busy.

From the fio testing data in cover letter, we can see the software
queue can improve some performance with 4K block size, increasing
about 16% for random read, increasing about 90% for random write,
though no obvious improvement for sequential read and write.

Moreover we can expand the software queue interface to support MMC
packed request or packed command in future.

Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Signed-off-by: Baolin Wang <baolin.wang7@gmail.com>
Link: https://lore.kernel.org/r/4409c1586a9b3ed20d57ad2faf6c262fc3ccb6e2.1581478568.git.baolin.wang7@gmail.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
2020-03-24 14:35:39 +01:00

545 lines
13 KiB
C
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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2003 Russell King, All Rights Reserved.
* Copyright 2006-2007 Pierre Ossman
*/
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/blkdev.h>
#include <linux/freezer.h>
#include <linux/kthread.h>
#include <linux/scatterlist.h>
#include <linux/dma-mapping.h>
#include <linux/backing-dev.h>
#include <linux/mmc/card.h>
#include <linux/mmc/host.h>
#include "queue.h"
#include "block.h"
#include "core.h"
#include "card.h"
#include "host.h"
#define MMC_DMA_MAP_MERGE_SEGMENTS 512
static inline bool mmc_cqe_dcmd_busy(struct mmc_queue *mq)
{
/* Allow only 1 DCMD at a time */
return mq->in_flight[MMC_ISSUE_DCMD];
}
void mmc_cqe_check_busy(struct mmc_queue *mq)
{
if ((mq->cqe_busy & MMC_CQE_DCMD_BUSY) && !mmc_cqe_dcmd_busy(mq))
mq->cqe_busy &= ~MMC_CQE_DCMD_BUSY;
mq->cqe_busy &= ~MMC_CQE_QUEUE_FULL;
}
static inline bool mmc_cqe_can_dcmd(struct mmc_host *host)
{
return host->caps2 & MMC_CAP2_CQE_DCMD;
}
static enum mmc_issue_type mmc_cqe_issue_type(struct mmc_host *host,
struct request *req)
{
switch (req_op(req)) {
case REQ_OP_DRV_IN:
case REQ_OP_DRV_OUT:
case REQ_OP_DISCARD:
case REQ_OP_SECURE_ERASE:
return MMC_ISSUE_SYNC;
case REQ_OP_FLUSH:
return mmc_cqe_can_dcmd(host) ? MMC_ISSUE_DCMD : MMC_ISSUE_SYNC;
default:
return MMC_ISSUE_ASYNC;
}
}
enum mmc_issue_type mmc_issue_type(struct mmc_queue *mq, struct request *req)
{
struct mmc_host *host = mq->card->host;
if (mq->use_cqe && !host->hsq_enabled)
return mmc_cqe_issue_type(host, req);
if (req_op(req) == REQ_OP_READ || req_op(req) == REQ_OP_WRITE)
return MMC_ISSUE_ASYNC;
return MMC_ISSUE_SYNC;
}
static void __mmc_cqe_recovery_notifier(struct mmc_queue *mq)
{
if (!mq->recovery_needed) {
mq->recovery_needed = true;
schedule_work(&mq->recovery_work);
}
}
void mmc_cqe_recovery_notifier(struct mmc_request *mrq)
{
struct mmc_queue_req *mqrq = container_of(mrq, struct mmc_queue_req,
brq.mrq);
struct request *req = mmc_queue_req_to_req(mqrq);
struct request_queue *q = req->q;
struct mmc_queue *mq = q->queuedata;
unsigned long flags;
spin_lock_irqsave(&mq->lock, flags);
__mmc_cqe_recovery_notifier(mq);
spin_unlock_irqrestore(&mq->lock, flags);
}
static enum blk_eh_timer_return mmc_cqe_timed_out(struct request *req)
{
struct mmc_queue_req *mqrq = req_to_mmc_queue_req(req);
struct mmc_request *mrq = &mqrq->brq.mrq;
struct mmc_queue *mq = req->q->queuedata;
struct mmc_host *host = mq->card->host;
enum mmc_issue_type issue_type = mmc_issue_type(mq, req);
bool recovery_needed = false;
switch (issue_type) {
case MMC_ISSUE_ASYNC:
case MMC_ISSUE_DCMD:
if (host->cqe_ops->cqe_timeout(host, mrq, &recovery_needed)) {
if (recovery_needed)
__mmc_cqe_recovery_notifier(mq);
return BLK_EH_RESET_TIMER;
}
/* No timeout (XXX: huh? comment doesn't make much sense) */
blk_mq_complete_request(req);
return BLK_EH_DONE;
default:
/* Timeout is handled by mmc core */
return BLK_EH_RESET_TIMER;
}
}
static enum blk_eh_timer_return mmc_mq_timed_out(struct request *req,
bool reserved)
{
struct request_queue *q = req->q;
struct mmc_queue *mq = q->queuedata;
struct mmc_card *card = mq->card;
struct mmc_host *host = card->host;
unsigned long flags;
int ret;
spin_lock_irqsave(&mq->lock, flags);
if (mq->recovery_needed || !mq->use_cqe || host->hsq_enabled)
ret = BLK_EH_RESET_TIMER;
else
ret = mmc_cqe_timed_out(req);
spin_unlock_irqrestore(&mq->lock, flags);
return ret;
}
static void mmc_mq_recovery_handler(struct work_struct *work)
{
struct mmc_queue *mq = container_of(work, struct mmc_queue,
recovery_work);
struct request_queue *q = mq->queue;
struct mmc_host *host = mq->card->host;
mmc_get_card(mq->card, &mq->ctx);
mq->in_recovery = true;
if (mq->use_cqe && !host->hsq_enabled)
mmc_blk_cqe_recovery(mq);
else
mmc_blk_mq_recovery(mq);
mq->in_recovery = false;
spin_lock_irq(&mq->lock);
mq->recovery_needed = false;
spin_unlock_irq(&mq->lock);
if (host->hsq_enabled)
host->cqe_ops->cqe_recovery_finish(host);
mmc_put_card(mq->card, &mq->ctx);
blk_mq_run_hw_queues(q, true);
}
static struct scatterlist *mmc_alloc_sg(int sg_len, gfp_t gfp)
{
struct scatterlist *sg;
sg = kmalloc_array(sg_len, sizeof(*sg), gfp);
if (sg)
sg_init_table(sg, sg_len);
return sg;
}
static void mmc_queue_setup_discard(struct request_queue *q,
struct mmc_card *card)
{
unsigned max_discard;
max_discard = mmc_calc_max_discard(card);
if (!max_discard)
return;
blk_queue_flag_set(QUEUE_FLAG_DISCARD, q);
blk_queue_max_discard_sectors(q, max_discard);
q->limits.discard_granularity = card->pref_erase << 9;
/* granularity must not be greater than max. discard */
if (card->pref_erase > max_discard)
q->limits.discard_granularity = 0;
if (mmc_can_secure_erase_trim(card))
blk_queue_flag_set(QUEUE_FLAG_SECERASE, q);
}
static unsigned int mmc_get_max_segments(struct mmc_host *host)
{
return host->can_dma_map_merge ? MMC_DMA_MAP_MERGE_SEGMENTS :
host->max_segs;
}
/**
* mmc_init_request() - initialize the MMC-specific per-request data
* @q: the request queue
* @req: the request
* @gfp: memory allocation policy
*/
static int __mmc_init_request(struct mmc_queue *mq, struct request *req,
gfp_t gfp)
{
struct mmc_queue_req *mq_rq = req_to_mmc_queue_req(req);
struct mmc_card *card = mq->card;
struct mmc_host *host = card->host;
mq_rq->sg = mmc_alloc_sg(mmc_get_max_segments(host), gfp);
if (!mq_rq->sg)
return -ENOMEM;
return 0;
}
static void mmc_exit_request(struct request_queue *q, struct request *req)
{
struct mmc_queue_req *mq_rq = req_to_mmc_queue_req(req);
kfree(mq_rq->sg);
mq_rq->sg = NULL;
}
static int mmc_mq_init_request(struct blk_mq_tag_set *set, struct request *req,
unsigned int hctx_idx, unsigned int numa_node)
{
return __mmc_init_request(set->driver_data, req, GFP_KERNEL);
}
static void mmc_mq_exit_request(struct blk_mq_tag_set *set, struct request *req,
unsigned int hctx_idx)
{
struct mmc_queue *mq = set->driver_data;
mmc_exit_request(mq->queue, req);
}
static blk_status_t mmc_mq_queue_rq(struct blk_mq_hw_ctx *hctx,
const struct blk_mq_queue_data *bd)
{
struct request *req = bd->rq;
struct request_queue *q = req->q;
struct mmc_queue *mq = q->queuedata;
struct mmc_card *card = mq->card;
struct mmc_host *host = card->host;
enum mmc_issue_type issue_type;
enum mmc_issued issued;
bool get_card, cqe_retune_ok;
int ret;
if (mmc_card_removed(mq->card)) {
req->rq_flags |= RQF_QUIET;
return BLK_STS_IOERR;
}
issue_type = mmc_issue_type(mq, req);
spin_lock_irq(&mq->lock);
if (mq->recovery_needed || mq->busy) {
spin_unlock_irq(&mq->lock);
return BLK_STS_RESOURCE;
}
switch (issue_type) {
case MMC_ISSUE_DCMD:
if (mmc_cqe_dcmd_busy(mq)) {
mq->cqe_busy |= MMC_CQE_DCMD_BUSY;
spin_unlock_irq(&mq->lock);
return BLK_STS_RESOURCE;
}
break;
case MMC_ISSUE_ASYNC:
/*
* For MMC host software queue, we only allow 2 requests in
* flight to avoid a long latency.
*/
if (host->hsq_enabled && mq->in_flight[issue_type] > 2) {
spin_unlock_irq(&mq->lock);
return BLK_STS_RESOURCE;
}
break;
default:
/*
* Timeouts are handled by mmc core, and we don't have a host
* API to abort requests, so we can't handle the timeout anyway.
* However, when the timeout happens, blk_mq_complete_request()
* no longer works (to stop the request disappearing under us).
* To avoid racing with that, set a large timeout.
*/
req->timeout = 600 * HZ;
break;
}
/* Parallel dispatch of requests is not supported at the moment */
mq->busy = true;
mq->in_flight[issue_type] += 1;
get_card = (mmc_tot_in_flight(mq) == 1);
cqe_retune_ok = (mmc_cqe_qcnt(mq) == 1);
spin_unlock_irq(&mq->lock);
if (!(req->rq_flags & RQF_DONTPREP)) {
req_to_mmc_queue_req(req)->retries = 0;
req->rq_flags |= RQF_DONTPREP;
}
if (get_card)
mmc_get_card(card, &mq->ctx);
if (mq->use_cqe) {
host->retune_now = host->need_retune && cqe_retune_ok &&
!host->hold_retune;
}
blk_mq_start_request(req);
issued = mmc_blk_mq_issue_rq(mq, req);
switch (issued) {
case MMC_REQ_BUSY:
ret = BLK_STS_RESOURCE;
break;
case MMC_REQ_FAILED_TO_START:
ret = BLK_STS_IOERR;
break;
default:
ret = BLK_STS_OK;
break;
}
if (issued != MMC_REQ_STARTED) {
bool put_card = false;
spin_lock_irq(&mq->lock);
mq->in_flight[issue_type] -= 1;
if (mmc_tot_in_flight(mq) == 0)
put_card = true;
mq->busy = false;
spin_unlock_irq(&mq->lock);
if (put_card)
mmc_put_card(card, &mq->ctx);
} else {
WRITE_ONCE(mq->busy, false);
}
return ret;
}
static const struct blk_mq_ops mmc_mq_ops = {
.queue_rq = mmc_mq_queue_rq,
.init_request = mmc_mq_init_request,
.exit_request = mmc_mq_exit_request,
.complete = mmc_blk_mq_complete,
.timeout = mmc_mq_timed_out,
};
static void mmc_setup_queue(struct mmc_queue *mq, struct mmc_card *card)
{
struct mmc_host *host = card->host;
unsigned block_size = 512;
blk_queue_flag_set(QUEUE_FLAG_NONROT, mq->queue);
blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, mq->queue);
if (mmc_can_erase(card))
mmc_queue_setup_discard(mq->queue, card);
if (!mmc_dev(host)->dma_mask || !*mmc_dev(host)->dma_mask)
blk_queue_bounce_limit(mq->queue, BLK_BOUNCE_HIGH);
blk_queue_max_hw_sectors(mq->queue,
min(host->max_blk_count, host->max_req_size / 512));
if (host->can_dma_map_merge)
WARN(!blk_queue_can_use_dma_map_merging(mq->queue,
mmc_dev(host)),
"merging was advertised but not possible");
blk_queue_max_segments(mq->queue, mmc_get_max_segments(host));
if (mmc_card_mmc(card))
block_size = card->ext_csd.data_sector_size;
blk_queue_logical_block_size(mq->queue, block_size);
/*
* After blk_queue_can_use_dma_map_merging() was called with succeed,
* since it calls blk_queue_virt_boundary(), the mmc should not call
* both blk_queue_max_segment_size().
*/
if (!host->can_dma_map_merge)
blk_queue_max_segment_size(mq->queue,
round_down(host->max_seg_size, block_size));
dma_set_max_seg_size(mmc_dev(host), queue_max_segment_size(mq->queue));
INIT_WORK(&mq->recovery_work, mmc_mq_recovery_handler);
INIT_WORK(&mq->complete_work, mmc_blk_mq_complete_work);
mutex_init(&mq->complete_lock);
init_waitqueue_head(&mq->wait);
}
static inline bool mmc_merge_capable(struct mmc_host *host)
{
return host->caps2 & MMC_CAP2_MERGE_CAPABLE;
}
/* Set queue depth to get a reasonable value for q->nr_requests */
#define MMC_QUEUE_DEPTH 64
/**
* mmc_init_queue - initialise a queue structure.
* @mq: mmc queue
* @card: mmc card to attach this queue
*
* Initialise a MMC card request queue.
*/
int mmc_init_queue(struct mmc_queue *mq, struct mmc_card *card)
{
struct mmc_host *host = card->host;
int ret;
mq->card = card;
mq->use_cqe = host->cqe_enabled;
spin_lock_init(&mq->lock);
memset(&mq->tag_set, 0, sizeof(mq->tag_set));
mq->tag_set.ops = &mmc_mq_ops;
/*
* The queue depth for CQE must match the hardware because the request
* tag is used to index the hardware queue.
*/
if (mq->use_cqe && !host->hsq_enabled)
mq->tag_set.queue_depth =
min_t(int, card->ext_csd.cmdq_depth, host->cqe_qdepth);
else
mq->tag_set.queue_depth = MMC_QUEUE_DEPTH;
mq->tag_set.numa_node = NUMA_NO_NODE;
mq->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_BLOCKING;
mq->tag_set.nr_hw_queues = 1;
mq->tag_set.cmd_size = sizeof(struct mmc_queue_req);
mq->tag_set.driver_data = mq;
/*
* Since blk_mq_alloc_tag_set() calls .init_request() of mmc_mq_ops,
* the host->can_dma_map_merge should be set before to get max_segs
* from mmc_get_max_segments().
*/
if (mmc_merge_capable(host) &&
host->max_segs < MMC_DMA_MAP_MERGE_SEGMENTS &&
dma_get_merge_boundary(mmc_dev(host)))
host->can_dma_map_merge = 1;
else
host->can_dma_map_merge = 0;
ret = blk_mq_alloc_tag_set(&mq->tag_set);
if (ret)
return ret;
mq->queue = blk_mq_init_queue(&mq->tag_set);
if (IS_ERR(mq->queue)) {
ret = PTR_ERR(mq->queue);
goto free_tag_set;
}
if (mmc_host_is_spi(host) && host->use_spi_crc)
mq->queue->backing_dev_info->capabilities |=
BDI_CAP_STABLE_WRITES;
mq->queue->queuedata = mq;
blk_queue_rq_timeout(mq->queue, 60 * HZ);
mmc_setup_queue(mq, card);
return 0;
free_tag_set:
blk_mq_free_tag_set(&mq->tag_set);
return ret;
}
void mmc_queue_suspend(struct mmc_queue *mq)
{
blk_mq_quiesce_queue(mq->queue);
/*
* The host remains claimed while there are outstanding requests, so
* simply claiming and releasing here ensures there are none.
*/
mmc_claim_host(mq->card->host);
mmc_release_host(mq->card->host);
}
void mmc_queue_resume(struct mmc_queue *mq)
{
blk_mq_unquiesce_queue(mq->queue);
}
void mmc_cleanup_queue(struct mmc_queue *mq)
{
struct request_queue *q = mq->queue;
/*
* The legacy code handled the possibility of being suspended,
* so do that here too.
*/
if (blk_queue_quiesced(q))
blk_mq_unquiesce_queue(q);
blk_cleanup_queue(q);
blk_mq_free_tag_set(&mq->tag_set);
/*
* A request can be completed before the next request, potentially
* leaving a complete_work with nothing to do. Such a work item might
* still be queued at this point. Flush it.
*/
flush_work(&mq->complete_work);
mq->card = NULL;
}
/*
* Prepare the sg list(s) to be handed of to the host driver
*/
unsigned int mmc_queue_map_sg(struct mmc_queue *mq, struct mmc_queue_req *mqrq)
{
struct request *req = mmc_queue_req_to_req(mqrq);
return blk_rq_map_sg(mq->queue, req, mqrq->sg);
}
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