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@xxxxxxxxxx>
---
drivers/block/mtip32xx/mtip32xx.c | 4 ++--
drivers/block/mtip32xx/mtip32xx.h | 1 +
2 files changed, 3 insertions(+), 2 deletions(-)
diff --git a/drivers/block/mtip32xx/mtip32xx.c b/drivers/block/mtip32xx/mtip32xx.c
index d8618a71da74..01e7fdfae0af 100644
--- a/drivers/block/mtip32xx/mtip32xx.c
+++ b/drivers/block/mtip32xx/mtip32xx.c
@@ -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,
diff --git a/drivers/block/mtip32xx/mtip32xx.h b/drivers/block/mtip32xx/mtip32xx.h
index e8286af50e16..e20e55dab443 100644
--- a/drivers/block/mtip32xx/mtip32xx.h
+++ b/drivers/block/mtip32xx/mtip32xx.h
@@ -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,
--
2.9.4
