mtip32xx: minor performance enhancements
This patch adds the following: 1) Compiler hinting in the fast path. 2) A prefetch of port->flags to eliminate moderate cpu stalling later in mtip_hw_submit_io(). 3) Eliminate a redundant rq_data_dir(). 4) Reorder members of driver_data to eliminate false cacheline sharing between irq_workers_active and unal_qdepth. With some workload and topology configurations, I'm seeing ~1.5% throughput improvement in small block random read benchmarks as well as improved latency std. dev. Signed-off-by: Sam Bradshaw <sbradshaw@micron.com> Add include of <linux/prefetch.h> Signed-off-by: Jens Axboe <axboe@fb.com>
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@ -39,6 +39,7 @@
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#include <../drivers/ata/ahci.h>
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#include <linux/export.h>
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#include <linux/debugfs.h>
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#include <linux/prefetch.h>
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#include "mtip32xx.h"
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#define HW_CMD_SLOT_SZ (MTIP_MAX_COMMAND_SLOTS * 32)
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@ -2380,6 +2381,8 @@ static void mtip_hw_submit_io(struct driver_data *dd, struct request *rq,
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/* Map the scatter list for DMA access */
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nents = dma_map_sg(&dd->pdev->dev, command->sg, nents, dma_dir);
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prefetch(&port->flags);
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command->scatter_ents = nents;
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/*
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@ -2392,7 +2395,7 @@ static void mtip_hw_submit_io(struct driver_data *dd, struct request *rq,
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fis = command->command;
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fis->type = 0x27;
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fis->opts = 1 << 7;
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if (rq_data_dir(rq) == READ)
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if (dma_dir == DMA_FROM_DEVICE)
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fis->command = ATA_CMD_FPDMA_READ;
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else
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fis->command = ATA_CMD_FPDMA_WRITE;
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@ -2412,7 +2415,7 @@ static void mtip_hw_submit_io(struct driver_data *dd, struct request *rq,
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fis->res3 = 0;
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fill_command_sg(dd, command, nents);
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if (command->unaligned)
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if (unlikely(command->unaligned))
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fis->device |= 1 << 7;
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/* Populate the command header */
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@ -2433,7 +2436,7 @@ static void mtip_hw_submit_io(struct driver_data *dd, struct request *rq,
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* To prevent this command from being issued
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* if an internal command is in progress or error handling is active.
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*/
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if (port->flags & MTIP_PF_PAUSE_IO) {
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if (unlikely(port->flags & MTIP_PF_PAUSE_IO)) {
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set_bit(rq->tag, port->cmds_to_issue);
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set_bit(MTIP_PF_ISSUE_CMDS_BIT, &port->flags);
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return;
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@ -3754,7 +3757,7 @@ static bool mtip_check_unal_depth(struct blk_mq_hw_ctx *hctx,
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struct driver_data *dd = hctx->queue->queuedata;
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struct mtip_cmd *cmd = blk_mq_rq_to_pdu(rq);
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if (!dd->unal_qdepth || rq_data_dir(rq) == READ)
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if (rq_data_dir(rq) == READ || !dd->unal_qdepth)
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return false;
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/*
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@ -3776,11 +3779,11 @@ static int mtip_queue_rq(struct blk_mq_hw_ctx *hctx, struct request *rq)
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{
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int ret;
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if (mtip_check_unal_depth(hctx, rq))
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if (unlikely(mtip_check_unal_depth(hctx, rq)))
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return BLK_MQ_RQ_QUEUE_BUSY;
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ret = mtip_submit_request(hctx, rq);
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if (!ret)
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if (likely(!ret))
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return BLK_MQ_RQ_QUEUE_OK;
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rq->errors = ret;
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@ -493,19 +493,19 @@ struct driver_data {
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struct workqueue_struct *isr_workq;
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struct mtip_work work[MTIP_MAX_SLOT_GROUPS];
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atomic_t irq_workers_active;
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struct mtip_work work[MTIP_MAX_SLOT_GROUPS];
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int isr_binding;
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struct block_device *bdev;
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int unal_qdepth; /* qdepth of unaligned IO queue */
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struct list_head online_list; /* linkage for online list */
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struct list_head remove_list; /* linkage for removing list */
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int unal_qdepth; /* qdepth of unaligned IO queue */
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};
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#endif
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