Hi Jeff,
Do you have any suggestion about this patch :)
> -----Original Message-----
> From: Liu Qiang-B32616
> Sent: Friday, January 20, 2012 10:19 AM
> To: jgarzik@xxxxxxxxx; linux-ide@xxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx; linuxppc-dev@xxxxxxxxxxxxxxxx; Liu
> Qiang-B32616
> Subject: [PATCH V2] fsl-sata: I/O load balancing
>
> From: Qiang Liu <qiang.liu@xxxxxxxxxxxxx>
>
> Reduce interrupt signals through reset Interrupt Coalescing Control Reg.
> Provide dynamic method to adjust interrupt signals and timer ticks by
> sysfs.
> It is a tradeoff for different applications.
>
> Signed-off-by: Qiang Liu <qiang.liu@xxxxxxxxxxxxx>
> ---
>
> change for V2
> support dynamic config interrupt coalescing register by /sysfs
> test random small file with iometer
> 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
> 3547000..41ca495 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 { @@ -263,9
> +282,66 @@ struct sata_fsl_host_priv {
> int irq;
> int data_snoop;
> u32 quirks;
> + struct device_attribute intr_coalescing;
> #define SATA_FSL_QUIRK_P3P5_ERRATA (1 << 0)
> };
>
> +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 void sata_fsl_dev_config(struct ata_device *dev) {
> dev->max_sectors = 16;
> @@ -352,11 +428,11 @@ 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_printk(qc->ap, KERN_ERR,
> "s/g addr unaligned : 0x%llx\n",
> (unsigned long long)sg_addr);
> - if (sg_len & 0x03)
> + if (unlikely(sg_len & 0x03))
> ata_port_printk(qc->ap, KERN_ERR,
> "s/g len unaligned : 0x%x\n", sg_len);
>
> @@ -1305,6 +1381,13 @@ static int sata_fsl_init_controller(struct
> ata_host *host)
> 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
> */
> @@ -1368,7 +1451,7 @@ 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]; @@ -1430,6
> +1513,10 @@ 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;
> @@ -1447,10 +1534,24 @@ 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)
> @@ -1464,6 +1565,8 @@ 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);
> --
> 1.7.5.1
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