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mtip32xx: avoid to read HOST_CAP from HW in .queue_rq() 

It is observed reading the register from HW takes a bit long,
for example in my box, the following difference of 'perf report
--no-children fio ...' can be seen when running I/O:

1) V4.12 without patch
+    9.28%       fio  [mtip32xx]           [k] mtip_irq_handler
+    8.48%       fio  [mtip32xx]           [k] mtip_init_cmd_header

2) V4.12 with the following patch
+    9.14%       fio  [mtip32xx]           [k] mtip_irq_handler
......
+    1.14%       fio  [mtip32xx]           [k] mtip_init_cmd_header

IOPS can be increased by ~5% with this patch too.

Fixes: a4e84aae8139(mtip32xx: use runtime tag to initialize command header)
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Ming Lei 2017-07-05 12:14:27 +08:00 committed by Jens Axboe
parent ea4d12dabf
commit 8a05aa4ce3
2 changed files with 3 additions and 2 deletions
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4
drivers/block/mtip32xx/mtip32xx.c
View File

@ -174,7 +174,6 @@ static void mtip_init_cmd_header(struct request *rq)
{
struct driver_data *dd = rq->q->queuedata;
struct mtip_cmd *cmd = blk_mq_rq_to_pdu(rq);
u32 host_cap_64 = readl(dd->mmio + HOST_CAP) & HOST_CAP_64;
/* Point the command headers at the command tables. */
cmd->command_header = dd->port->command_list +
@ -182,7 +181,7 @@ static void mtip_init_cmd_header(struct request *rq)
cmd->command_header_dma = dd->port->command_list_dma +
(sizeof(struct mtip_cmd_hdr) * rq->tag);
if (host_cap_64)
if (test_bit(MTIP_PF_HOST_CAP_64, &dd->port->flags))
cmd->command_header->ctbau = __force_bit2int cpu_to_le32((cmd->command_dma >> 16) >> 16);
cmd->command_header->ctba = __force_bit2int cpu_to_le32(cmd->command_dma & 0xFFFFFFFF);
@ -386,6 +385,7 @@ static void mtip_init_port(struct mtip_port *port)
port->mmio + PORT_LST_ADDR_HI);
writel((port->rxfis_dma >> 16) >> 16,
port->mmio + PORT_FIS_ADDR_HI);
set_bit(MTIP_PF_HOST_CAP_64, &port->flags);
}
writel(port->command_list_dma & 0xFFFFFFFF,

1
drivers/block/mtip32xx/mtip32xx.h
View File

@ -140,6 +140,7 @@ enum {
(1 << MTIP_PF_SE_ACTIVE_BIT) |
(1 << MTIP_PF_DM_ACTIVE_BIT) |
(1 << MTIP_PF_TO_ACTIVE_BIT)),
MTIP_PF_HOST_CAP_64 = 10, /* cache HOST_CAP_64 */
MTIP_PF_SVC_THD_ACTIVE_BIT = 4,
MTIP_PF_ISSUE_CMDS_BIT = 5,