Adds support for interrupt coalescing feature to reduce interrupt events.
Provides a mechanism of adjusting coalescing count and timeout tick by sysfs
at runtime, so that tradeoff of latency and CPU load can be made depending
on different applications.
Signed-off-by: Qiang Liu <qiang.liu@xxxxxxxxxxxxx>
---
change for V3
change the title and comments according the feedback
support dynamic config interrupt coalescing register by /sysfs
test random small file with iometer
adjust kernel source baseline for apply upstream
Description:
1. fsl-sata interrupt will be raised 130 thousand times when write 8G file
(dd if=/dev/zero of=/dev/sda2 bs=128K count=65536);
2. most of interrupts raised because of only 1-4 commands completed;
3. only 30 thousand times will be raised after set max interrupt threshold,
more interrupts are coalesced as the description of ICC;
Test methods and results:
1. test sequential large file performance,
[root@p2020ds root]# echo 31 524287 > \
/sys/devices/soc.0/ffe18000.sata/intr_coalescing
[root@p2020ds root]# dd if=/dev/zero of=/dev/sda2 bs=128K count=65536 &
[root@p2020ds root]# top
CPU % | dd | flush-8:0 | softirq
---------------------------------------
before | 20-22 | 17-19 | 7
---------------------------------------
after | 18-21 | 15-16 | 5
---------------------------------------
2. test random small file with iometer,
iometer paramters:
4 I/Os burst length, 1MB transfer request size, 100% write, 2MB file size
as default configuration of interrupt coalescing register, 1 interrupts and
no timeout config, total write performance is 119MB per second,
after config with the maximum value, write performance is 110MB per second.
After compare the test results, a configuable interrupt coalescing should be
better when cope with flexible context.
drivers/ata/sata_fsl.c | 111 ++++++++++++++++++++++++++++++++++++++++++++++--
1 files changed, 107 insertions(+), 4 deletions(-)
diff --git a/drivers/ata/sata_fsl.c b/drivers/ata/sata_fsl.c
index 0120b0d..d6577b9 100644
--- a/drivers/ata/sata_fsl.c
+++ b/drivers/ata/sata_fsl.c
@@ -6,7 +6,7 @@
* Author: Ashish Kalra <ashish.kalra@xxxxxxxxxxxxx>
* Li Yang <leoli@xxxxxxxxxxxxx>
*
- * Copyright (c) 2006-2007, 2011 Freescale Semiconductor, Inc.
+ * Copyright (c) 2006-2007, 2011-2012 Freescale Semiconductor, Inc.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
@@ -26,6 +26,15 @@
#include <asm/io.h>
#include <linux/of_platform.h>
+static unsigned int intr_coalescing_count;
+module_param(intr_coalescing_count, int, S_IRUGO);
+MODULE_PARM_DESC(intr_coalescing_count,
+ "INT coalescing count threshold (1..31)");
+
+static unsigned int intr_coalescing_ticks;
+module_param(intr_coalescing_ticks, int, S_IRUGO);
+MODULE_PARM_DESC(intr_coalescing_ticks,
+ "INT coalescing timer threshold in AHB ticks");
/* Controller information */
enum {
SATA_FSL_QUEUE_DEPTH = 16,
@@ -83,6 +92,16 @@ enum {
};
/*
+ * Interrupt Coalescing Control Register bitdefs */
+enum {
+ ICC_MIN_INT_COUNT_THRESHOLD = 1,
+ ICC_MAX_INT_COUNT_THRESHOLD = ((1 << 5) - 1),
+ ICC_MIN_INT_TICKS_THRESHOLD = 0,
+ ICC_MAX_INT_TICKS_THRESHOLD = ((1 << 19) - 1),
+ ICC_SAFE_INT_TICKS = 1,
+};
+
+/*
* Host Controller command register set - per port
*/
enum {
@@ -263,8 +282,65 @@ struct sata_fsl_host_priv {
void __iomem *csr_base;
int irq;
int data_snoop;
+ struct device_attribute intr_coalescing;
};
+static void fsl_sata_set_irq_coalescing(struct ata_host *host,
+ unsigned int count, unsigned int ticks)
+{
+ struct sata_fsl_host_priv *host_priv = host->private_data;
+ void __iomem *hcr_base = host_priv->hcr_base;
+
+ if (count > ICC_MAX_INT_COUNT_THRESHOLD)
+ count = ICC_MAX_INT_COUNT_THRESHOLD;
+ else if (count < ICC_MIN_INT_COUNT_THRESHOLD)
+ count = ICC_MIN_INT_COUNT_THRESHOLD;
+
+ if (ticks > ICC_MAX_INT_TICKS_THRESHOLD)
+ ticks = ICC_MAX_INT_TICKS_THRESHOLD;
+ else if ((ICC_MIN_INT_TICKS_THRESHOLD == ticks) &&
+ (count > ICC_MIN_INT_COUNT_THRESHOLD))
+ ticks = ICC_SAFE_INT_TICKS;
+
+ spin_lock(&host->lock);
+ iowrite32((count << 24 | ticks), hcr_base + ICC);
+
+ intr_coalescing_count = count;
+ intr_coalescing_ticks = ticks;
+ spin_unlock(&host->lock);
+
+ DPRINTK("intrrupt coalescing, count = 0x%x, ticks = %x\n",
+ intr_coalescing_count, intr_coalescing_ticks);
+ DPRINTK("ICC register status: (hcr base: 0x%x) = 0x%x\n",
+ hcr_base, ioread32(hcr_base + ICC));
+}
+
+static ssize_t fsl_sata_intr_coalescing_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ return sprintf(buf, "%d %d\n",
+ intr_coalescing_count, intr_coalescing_ticks);
+}
+
+static ssize_t fsl_sata_intr_coalescing_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ unsigned int coalescing_count, coalescing_ticks;
+
+ if (sscanf(buf, "%d%d",
+ &coalescing_count,
+ &coalescing_ticks) != 2) {
+ printk(KERN_ERR "fsl-sata: wrong parameter format.\n");
+ return -EINVAL;
+ }
+
+ fsl_sata_set_irq_coalescing(dev_get_drvdata(dev),
+ coalescing_count, coalescing_ticks);
+
+ return strlen(buf);
+}
+
static inline unsigned int sata_fsl_tag(unsigned int tag,
void __iomem *hcr_base)
{
@@ -346,10 +422,10 @@ static unsigned int sata_fsl_fill_sg(struct ata_queued_cmd *qc, void *cmd_desc,
(unsigned long long)sg_addr, sg_len);
/* warn if each s/g element is not dword aligned */
- if (sg_addr & 0x03)
+ if (unlikely(sg_addr & 0x03))
ata_port_err(qc->ap, "s/g addr unaligned : 0x%llx\n",
(unsigned long long)sg_addr);
- if (sg_len & 0x03)
+ if (unlikely(sg_len & 0x03))
ata_port_err(qc->ap, "s/g len unaligned : 0x%x\n",
sg_len);
@@ -1245,6 +1321,13 @@ static int sata_fsl_init_controller(struct ata_host *host)
iowrite32(0x00000FFFF, hcr_base + CE);
iowrite32(0x00000FFFF, hcr_base + DE);
+ /*
+ * reset the number of command complete bits which will cause the
+ * interrupt to be signaled
+ */
+ fsl_sata_set_irq_coalescing(host, intr_coalescing_count,
+ intr_coalescing_ticks);
+
/*
* host controller will be brought on-line, during xx_port_start()
* callback, that should also initiate the OOB, COMINIT sequence
@@ -1309,7 +1392,7 @@ static int sata_fsl_probe(struct platform_device *ofdev)
void __iomem *csr_base = NULL;
struct sata_fsl_host_priv *host_priv = NULL;
int irq;
- struct ata_host *host;
+ struct ata_host *host = NULL;
u32 temp;
struct ata_port_info pi = sata_fsl_port_info[0];
@@ -1356,6 +1439,10 @@ static int sata_fsl_probe(struct platform_device *ofdev)
/* allocate host structure */
host = ata_host_alloc_pinfo(&ofdev->dev, ppi, SATA_FSL_MAX_PORTS);
+ if (!host) {
+ retval = -ENOMEM;
+ goto error_exit_with_cleanup;
+ }
/* host->iomap is not used currently */
host->private_data = host_priv;
@@ -1373,10 +1460,24 @@ static int sata_fsl_probe(struct platform_device *ofdev)
dev_set_drvdata(&ofdev->dev, host);
+ host_priv->intr_coalescing.show = fsl_sata_intr_coalescing_show;
+ host_priv->intr_coalescing.store = fsl_sata_intr_coalescing_store;
+ sysfs_attr_init(&host_priv->intr_coalescing.attr);
+ host_priv->intr_coalescing.attr.name = "intr_coalescing";
+ host_priv->intr_coalescing.attr.mode = S_IRUGO | S_IWUSR;
+ retval = device_create_file(host->dev, &host_priv->intr_coalescing);
+ if (retval)
+ goto error_exit_with_cleanup;
+
return 0;
error_exit_with_cleanup:
+ if (host) {
+ dev_set_drvdata(&ofdev->dev, NULL);
+ ata_host_detach(host);
+ }
+
if (hcr_base)
iounmap(hcr_base);
if (host_priv)
@@ -1390,6 +1491,8 @@ static int sata_fsl_remove(struct platform_device *ofdev)
struct ata_host *host = dev_get_drvdata(&ofdev->dev);
struct sata_fsl_host_priv *host_priv = host->private_data;
+ device_remove_file(&ofdev->dev, &host_priv->intr_coalescing);
+
ata_host_detach(host);
dev_set_drvdata(&ofdev->dev, NULL);
--
1.6.4
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