RE: [PATCH 09/15] megaraid_sas: Dual Queue depth support

[Sumit Saxena <sumit.saxena@avagotech.com>]

> -----Original Message-----
> From: Tomas Henzl [mailto:thenzl@redhat.com]
> Sent: Tuesday, January 19, 2016 7:04 PM
> To: Sumit Saxena; jbottomley@parallels.com; hch@infradead.org;
> martin.petersen@oracle.com
> Cc: linux-scsi@vger.kernel.org; kashyap.desai@avagotech.com
> Subject: Re: [PATCH 09/15] megaraid_sas: Dual Queue depth support
>
> On 18.12.2015 14:27, Sumit Saxena wrote:
> > This patch will add support for Dual Queue depth reported by firmware.
> >
> > Below are key points-
> >
> > 1. For iMR controllers, firmware will report two queue depths- 1.
Controller
> wide Queue depth 2. LDIO Queue depth(240).
> > Ofcourse, Controller wide Queue depth will be greater among two. Using
> > this new method, iMR can provide larger Queue depth(QD) for JBOD and
> > limited QD for Virtual Disk(VD). This feature gives benefit for iMR
product
> which will be used for deployment with large number of JBOD and limited
> number of VD on setup.
> > 2. megaraid_sas driver will throttle Read write LDIOs based when RW
LDIOs
> reaches "LDIO Queue Depth".
> > 3. This feature of dual queue depth can enabled/disabled via module
> parameter. Default behavior is: Dual Queue depth is enabled.
> > 4. Added sysfs parameter "ldio_outstanding" for user to read LDIO
outstanding
> at run time.
> >
> >
> > Signed-off-by: Sumit Saxena <sumit.saxena@avagotech.com>
> > Signed-off-by: Kashyap Desai <kashyap.desai@avagotech.com>
> > ---
> >  drivers/scsi/megaraid/megaraid_sas.h        |    9 +++
> >  drivers/scsi/megaraid/megaraid_sas_base.c   |   20 ++++++-
> >  drivers/scsi/megaraid/megaraid_sas_fusion.c |   89
> ++++++++++++++++++++++++---
> >  3 files changed, 108 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/scsi/megaraid/megaraid_sas.h
> > b/drivers/scsi/megaraid/megaraid_sas.h
> > index c539516..4595ef4 100644
> > --- a/drivers/scsi/megaraid/megaraid_sas.h
> > +++ b/drivers/scsi/megaraid/megaraid_sas.h
> > @@ -1353,6 +1353,12 @@ enum DCMD_TIMEOUT_ACTION {
> >  	KILL_ADAPTER = 1,
> >  	IGNORE_TIMEOUT = 2,
> >  };
> > +
> > +enum FW_BOOT_CONTEXT {
> > +	PROBE_CONTEXT = 0,
> > +	OCR_CONTEXT = 1,
> > +};
> > +
> >  /* Frame Type */
> >  #define IO_FRAME				0
> >  #define PTHRU_FRAME				1
> > @@ -2038,6 +2044,8 @@ struct megasas_instance {
> >  	u16 max_fw_cmds;
> >  	u16 max_mfi_cmds;
> >  	u16 max_scsi_cmds;
> > +	u16 ldio_threshold;
> > +	u16 cur_can_queue;
> >  	u32 max_sectors_per_req;
> >  	struct megasas_aen_event *ev;
> >
> > @@ -2068,6 +2076,7 @@ struct megasas_instance {
> >  	u32 fw_support_ieee;
> >
> >  	atomic_t fw_outstanding;
> > +	atomic_t ldio_outstanding;
> >  	atomic_t fw_reset_no_pci_access;
> >
> >  	struct megasas_instance_template *instancet; diff --git
> > a/drivers/scsi/megaraid/megaraid_sas_base.c
> > b/drivers/scsi/megaraid/megaraid_sas_base.c
> > index 3454c5e..edc26fb 100644
> > --- a/drivers/scsi/megaraid/megaraid_sas_base.c
> > +++ b/drivers/scsi/megaraid/megaraid_sas_base.c
> > @@ -96,6 +96,10 @@ int rdpq_enable = 1;  module_param(rdpq_enable,
> > int, S_IRUGO);  MODULE_PARM_DESC(rdpq_enable, " Allocate reply queue
> > in chunks for large queue depth enable/disbale Default: disable(0)");
> >
> > +unsigned int dual_qdepth_disable;
> > +module_param(dual_qdepth_disable, int, S_IRUGO);
> > +MODULE_PARM_DESC(dual_qdepth_disable, "Disable dual queue depth
> > +feature. Default: 0");
> > +
> >  MODULE_LICENSE("GPL");
> >  MODULE_VERSION(MEGASAS_VERSION);
> >  MODULE_AUTHOR("megaraidlinux.pdl@avagotech.com");
> > @@ -1977,7 +1981,7 @@ megasas_check_and_restore_queue_depth(struct
> megasas_instance *instance)
> >  		spin_lock_irqsave(instance->host->host_lock, flags);
> >  		instance->flag &= ~MEGASAS_FW_BUSY;
> >
> > -		instance->host->can_queue = instance->max_scsi_cmds;
> > +		instance->host->can_queue = instance->cur_can_queue;
> >  		spin_unlock_irqrestore(instance->host->host_lock, flags);
> >  	}
> >  }
> > @@ -2942,6 +2946,16 @@ megasas_page_size_show(struct device *cdev,
> >  	return snprintf(buf, PAGE_SIZE, "%ld\n", (unsigned long)PAGE_SIZE
-
> > 1);  }
> >
> > +static ssize_t
> > +megasas_ldio_outstanding_show(struct device *cdev, struct
device_attribute
> *attr,
> > +	char *buf)
> > +{
> > +	struct Scsi_Host *shost = class_to_shost(cdev);
> > +	struct megasas_instance *instance = (struct megasas_instance
> > +*)shost->hostdata;
> > +
> > +	return snprintf(buf, PAGE_SIZE, "%d\n",
> > +atomic_read(&instance->ldio_outstanding));
> > +}
> > +
> >  static DEVICE_ATTR(fw_crash_buffer, S_IRUGO | S_IWUSR,
> >  	megasas_fw_crash_buffer_show, megasas_fw_crash_buffer_store);
> > static DEVICE_ATTR(fw_crash_buffer_size, S_IRUGO, @@ -2950,12 +2964,15
> > @@ static DEVICE_ATTR(fw_crash_state, S_IRUGO | S_IWUSR,
> >  	megasas_fw_crash_state_show, megasas_fw_crash_state_store);
> static
> > DEVICE_ATTR(page_size, S_IRUGO,
> >  	megasas_page_size_show, NULL);
> > +static DEVICE_ATTR(ldio_outstanding, S_IRUGO,
> > +	megasas_ldio_outstanding_show, NULL);
> >
> >  struct device_attribute *megaraid_host_attrs[] = {
> >  	&dev_attr_fw_crash_buffer_size,
> >  	&dev_attr_fw_crash_buffer,
> >  	&dev_attr_fw_crash_state,
> >  	&dev_attr_page_size,
> > +	&dev_attr_ldio_outstanding,
> >  	NULL,
> >  };
> >
> > @@ -4750,6 +4767,7 @@ megasas_init_adapter_mfi(struct megasas_instance
> *instance)
> >  		sema_init(&instance->ioctl_sem,
> (MEGASAS_MFI_IOCTL_CMDS));
> >  	}
> >
> > +	instance->cur_can_queue = instance->max_scsi_cmds;
> >  	/*
> >  	 * Create a pool of commands
> >  	 */
> > diff --git a/drivers/scsi/megaraid/megaraid_sas_fusion.c
> > b/drivers/scsi/megaraid/megaraid_sas_fusion.c
> > index 9ad779d..7cc7806 100644
> > --- a/drivers/scsi/megaraid/megaraid_sas_fusion.c
> > +++ b/drivers/scsi/megaraid/megaraid_sas_fusion.c
> > @@ -92,6 +92,7 @@ void megasas_start_timer(struct megasas_instance
> *instance,
> >  			 void *fn, unsigned long interval);  extern struct
> > megasas_mgmt_info megasas_mgmt_info;  extern int resetwaittime;
> > +extern unsigned int dual_qdepth_disable;
> >  static void megasas_free_rdpq_fusion(struct megasas_instance
> > *instance);  static void megasas_free_reply_fusion(struct
> > megasas_instance *instance);
> >
> > @@ -208,6 +209,67 @@ megasas_fire_cmd_fusion(struct megasas_instance
> > *instance,  }
> >
> >  /**
> > + * megasas_fusion_update_can_queue -	Do all Adapter Queue depth
> related calculations here
> > + * @instance:
> 	Adapter soft state
> > + * fw_boot_context:
Whether this
> function called during probe or after OCR
> > + *
> > + * This function is only for fusion controllers.
> > + * Update host can queue, if firmware downgrade max supported
firmware
> commands.
> > + * Firmware upgrade case will be skiped because underlying firmware
> > +has
> > + * more resource than exposed to the OS.
> > + *
> > + */
> > +static void
> > +megasas_fusion_update_can_queue(struct megasas_instance *instance,
> > +int fw_boot_context) {
> > +	u16 cur_max_fw_cmds = 0;
> > +	u16 ldio_threshold = 0;
> > +	struct megasas_register_set __iomem *reg_set;
> > +
> > +	reg_set = instance->reg_set;
> > +
> > +	cur_max_fw_cmds = readl(&instance->reg_set-
> >outbound_scratch_pad_3)
> > +& 0x00FFFF;
> > +
> > +	if (dual_qdepth_disable || !cur_max_fw_cmds)
> > +		cur_max_fw_cmds = instance->instancet-
> >read_fw_status_reg(reg_set) & 0x00FFFF;
> > +	else
> > +		ldio_threshold =
> > +			(instance->instancet->read_fw_status_reg(reg_set)
&
> 0x00FFFF) -
> > +MEGASAS_FUSION_IOCTL_CMDS;
> > +
> > +	dev_info(&instance->pdev->dev,
> > +			"Current firmware maximum commands: %d\t LDIO
> thershold: %d\n",
>
> a typo in "thershold"
>
> > +			cur_max_fw_cmds, ldio_threshold);
> > +
> > +	if (fw_boot_context == OCR_CONTEXT) {
> > +		cur_max_fw_cmds = cur_max_fw_cmds - 1;
> > +		if (cur_max_fw_cmds <= instance->max_fw_cmds) {
>
> probably '<' instead of '<=" could be here ?
>
> > +			instance->cur_can_queue =
> > +				cur_max_fw_cmds -
> (MEGASAS_FUSION_INTERNAL_CMDS +
> > +
> 	MEGASAS_FUSION_IOCTL_CMDS);
> > +			instance->host->can_queue = instance-
> >cur_can_queue;
> > +			instance->ldio_threshold = ldio_threshold;
> > +		}
> > +	} else {
> > +		instance->max_fw_cmds = cur_max_fw_cmds;
> > +		instance->ldio_threshold = ldio_threshold;
> > +
> > +		if (!instance->is_rdpq)
> > +			instance->max_fw_cmds = min_t(u16, instance-
> >max_fw_cmds, 1024);
> > +
> > +		/*
> > +		* Reduce the max supported cmds by 1. This is to ensure
that
> the
> > +		* reply_q_sz (1 more than the max cmd that driver may
send)
> > +		* does not exceed max cmds that the FW can support
> > +		*/
> > +		instance->max_fw_cmds = instance->max_fw_cmds-1;
> > +
> > +		instance->max_scsi_cmds = instance->max_fw_cmds -
> > +				(MEGASAS_FUSION_INTERNAL_CMDS +
> > +				MEGASAS_FUSION_IOCTL_CMDS);
> > +		instance->cur_can_queue = instance->max_scsi_cmds;
> > +	}
> > +}
> > +/**
> >   * megasas_free_cmds_fusion -	Free all the cmds in the free cmd
pool
> >   * @instance:		Adapter soft state
> >   */
> > @@ -736,6 +798,8 @@ megasas_ioc_init_fusion(struct megasas_instance
> *instance)
> >  		drv_ops->mfi_capabilities.support_ext_io_size = 1;
> >
> >  	drv_ops->mfi_capabilities.support_fp_rlbypass = 1;
> > +	if (!dual_qdepth_disable)
> > +		drv_ops->mfi_capabilities.support_ext_queue_depth = 1;
> >
> >  	/* Convert capability to LE32 */
> >  	cpu_to_le32s((u32
> > *)&init_frame->driver_operations.mfi_capabilities);
> > @@ -1151,15 +1215,7 @@ megasas_init_adapter_fusion(struct
> > megasas_instance *instance)
> >
> >  	reg_set = instance->reg_set;
> >
> > -	/*
> > -	 * Get various operational parameters from status register
> > -	 */
> > -	instance->max_fw_cmds =
> > -		instance->instancet->read_fw_status_reg(reg_set) &
0x00FFFF;
> > -	dev_info(&instance->pdev->dev,
> > -		"firmware support max fw cmd\t: (%d)\n", instance-
> >max_fw_cmds);
> > -	if (!instance->is_rdpq)
> > -		instance->max_fw_cmds = min_t(u16, instance-
> >max_fw_cmds, 1024);
> > +	megasas_fusion_update_can_queue(instance, PROBE_CONTEXT);
> >
> >  	/*
> >  	 * Reduce the max supported cmds by 1. This is to ensure that the
@@
> > -2117,6 +2173,15 @@ megasas_build_and_issue_cmd_fusion(struct
> > megasas_instance *instance,
> >
> >  	fusion = instance->ctrl_context;
> >
> > +	if (megasas_cmd_type(scmd) == READ_WRITE_LDIO) {
> > +		if (instance->ldio_threshold &&
> > +			(atomic_read(&instance->ldio_outstanding) >=
> > +			instance->ldio_threshold))
>
> This test above won't you protect when several processes read the same
value
> in parallel, so it may happen that you get over the limit set for
ldio_threshold.
> (You might use instead a construction with atomic_dec_and_test for
example)

Agree..I will fix this and send updated patch.
>
> tomash