Re: [PATCH 2/2] scsi: ufs-qcom: Add one sysfs node to monitor performance

[Greg KH]

On Mon, Jan 04, 2021 at 07:15:51PM -0800, Can Guo wrote:
> Add one sysfs node to monitor driver layer performance data. One can
> manipulate it to get performance related statistics during runtime.
> 
> Signed-off-by: Can Guo <cang@xxxxxxxxxxxxxx>

You did not create a Documentation/ABI/ update for this, explaining how
this file works, so there's no way to properly review this :(


> 
> diff --git a/drivers/scsi/ufs/ufs-qcom.c b/drivers/scsi/ufs/ufs-qcom.c
> index 2206b1e..5303ce9 100644
> --- a/drivers/scsi/ufs/ufs-qcom.c
> +++ b/drivers/scsi/ufs/ufs-qcom.c
> @@ -42,6 +42,7 @@ static struct ufs_qcom_host *ufs_qcom_hosts[MAX_UFS_QCOM_HOSTS];
>  static void ufs_qcom_get_default_testbus_cfg(struct ufs_qcom_host *host);
>  static int ufs_qcom_set_dme_vs_core_clk_ctrl_clear_div(struct ufs_hba *hba,
>  						       u32 clk_cycles);
> +static int ufs_qcom_init_sysfs(struct ufs_hba *hba);
>  
>  static struct ufs_qcom_host *rcdev_to_ufs_host(struct reset_controller_dev *rcd)
>  {
> @@ -1088,6 +1089,8 @@ static int ufs_qcom_init(struct ufs_hba *hba)
>  		err = 0;
>  	}
>  
> +	ufs_qcom_init_sysfs(hba);
> +
>  	goto out;
>  
>  out_variant_clear:
> @@ -1453,6 +1456,85 @@ static void ufs_qcom_config_scaling_param(struct ufs_hba *hba,
>  }
>  #endif
>  
> +static inline int ufs_qcom_opcode_rw_dir(u8 opcode)
> +{
> +	if (opcode == READ_6 || opcode == READ_10 || opcode == READ_16)
> +		return READ;
> +	else if (opcode == WRITE_6 || opcode == WRITE_10 || opcode == WRITE_16)
> +		return WRITE;
> +	else
> +		return -EINVAL;
> +}
> +
> +static inline bool ufs_qcom_should_start_monitor(struct ufs_qcom_host *host,
> +						 struct ufshcd_lrb *lrbp)
> +{
> +	return (host->monitor.enabled && lrbp && lrbp->cmd &&
> +		ktime_before(host->monitor.enabled_ts, lrbp->issue_time_stamp));
> +}
> +
> +static void ufs_qcom_monitor_start_busy(struct ufs_hba *hba, int tag)
> +{
> +	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
> +	struct ufshcd_lrb *lrbp;
> +	int dir;
> +
> +	lrbp = &hba->lrb[tag];
> +	if (ufs_qcom_should_start_monitor(host, lrbp)) {
> +		dir = ufs_qcom_opcode_rw_dir(*lrbp->cmd->cmnd);
> +		if (dir >= 0 && host->monitor.nr_queued[dir]++ == 0)
> +			host->monitor.busy_start_ts[dir] =
> +						lrbp->issue_time_stamp;
> +	}
> +}
> +
> +static void ufs_qcom_update_monitor(struct ufs_hba *hba, int tag)
> +{
> +	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
> +	struct ufshcd_lrb *lrbp;
> +	int dir;
> +
> +	lrbp = &hba->lrb[tag];
> +	if (ufs_qcom_should_start_monitor(host, lrbp)) {
> +		dir = ufs_qcom_opcode_rw_dir(*lrbp->cmd->cmnd);
> +		if (dir >= 0 && host->monitor.nr_queued[dir] > 0) {
> +			struct request *req;
> +			struct ufs_qcom_perf_monitor *mon;
> +			ktime_t now, inc, lat;
> +
> +			mon = &host->monitor;
> +			req = lrbp->cmd->request;
> +			mon->nr_sec_rw[dir] += blk_rq_sectors(req);
> +			now = ktime_get();
> +			inc = ktime_sub(now, mon->busy_start_ts[dir]);
> +			mon->total_busy[dir] =
> +				ktime_add(mon->total_busy[dir], inc);
> +			/* push forward the busy start of monitor */
> +			mon->busy_start_ts[dir] = now;
> +			mon->nr_queued[dir]--;
> +
> +			/* update latencies */
> +			mon->nr_req[dir]++;
> +			lat = ktime_sub(now, lrbp->issue_time_stamp);
> +			mon->lat_sum[dir] += lat;
> +			if (mon->lat_max[dir] < lat || !mon->lat_max[dir])
> +				mon->lat_max[dir] = lat;
> +			if (mon->lat_min[dir] > lat || !mon->lat_min[dir])
> +				mon->lat_min[dir] = lat;
> +		}
> +	}
> +}
> +
> +static void ufs_qcom_setup_xfer_req(struct ufs_hba *hba, int tag, bool is_scsi_cmd)
> +{
> +	ufs_qcom_monitor_start_busy(hba, tag);
> +}
> +
> +static void ufs_qcom_compl_xfer_req(struct ufs_hba *hba, int tag, bool is_scsi_cmd)
> +{
> +	ufs_qcom_update_monitor(hba, tag);
> +}
> +
>  /*
>   * struct ufs_hba_qcom_vops - UFS QCOM specific variant operations
>   *
> @@ -1476,8 +1558,112 @@ static const struct ufs_hba_variant_ops ufs_hba_qcom_vops = {
>  	.device_reset		= ufs_qcom_device_reset,
>  	.config_scaling_param = ufs_qcom_config_scaling_param,
>  	.program_key		= ufs_qcom_ice_program_key,
> +	.setup_xfer_req         = ufs_qcom_setup_xfer_req,
> +	.compl_xfer_req         = ufs_qcom_compl_xfer_req,
>  };
>  
> +static ssize_t monitor_show(struct device *dev, struct device_attribute *attr,
> +			    char *buf)
> +{
> +	struct ufs_hba *hba = dev_get_drvdata(dev);
> +	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
> +	struct ufs_qcom_perf_monitor *mon = &host->monitor;
> +	unsigned long nr_sec_rd, nr_sec_wr, busy_us_rd, busy_us_wr;
> +	unsigned long lat_max_rd, lat_min_rd, lat_sum_rd, lat_avg_rd, nr_req_rd;
> +	unsigned long lat_max_wr, lat_min_wr, lat_sum_wr, lat_avg_wr, nr_req_wr;
> +	bool is_enabled;
> +
> +	/*
> +	 * Don't lock the host lock since user needs to cat the entry very
> +	 * frequently during performance test, otherwise it may impact the
> +	 * performance.
> +	 */
> +	is_enabled = mon->enabled;
> +	if (!is_enabled)
> +		goto print_usage;
> +
> +	nr_sec_rd = mon->nr_sec_rw[READ];
> +	nr_sec_wr = mon->nr_sec_rw[WRITE];
> +	busy_us_rd = ktime_to_us(mon->total_busy[READ]);
> +	busy_us_wr = ktime_to_us(mon->total_busy[WRITE]);
> +
> +	nr_req_rd = mon->nr_req[READ];
> +	lat_max_rd = ktime_to_us(mon->lat_max[READ]);
> +	lat_min_rd = ktime_to_us(mon->lat_min[READ]);
> +	lat_sum_rd = ktime_to_us(mon->lat_sum[READ]);
> +	lat_avg_rd = lat_sum_rd / nr_req_rd;
> +
> +	nr_req_wr = mon->nr_req[WRITE];
> +	lat_max_wr = ktime_to_us(mon->lat_max[WRITE]);
> +	lat_min_wr = ktime_to_us(mon->lat_min[WRITE]);
> +	lat_sum_wr = ktime_to_us(mon->lat_sum[WRITE]);
> +	lat_avg_wr = lat_sum_wr / nr_req_wr;
> +
> +	return scnprintf(buf, PAGE_SIZE, "Read %lu %s %lu us, %lu %s max %lu | min %lu | avg %lu | sum %lu\nWrite %lu %s %lu us, %lu %s max %lu | min %lu | avg %lu | sum %lu\n",
> +		 nr_sec_rd, "sectors (in 512 bytes) in ", busy_us_rd,
> +		 nr_req_rd, "read reqs completed, latencies in us: ",
> +		 lat_max_rd, lat_min_rd, lat_avg_rd, lat_sum_rd,
> +		 nr_sec_wr, "sectors (in 512 bytes) in ", busy_us_wr,
> +		 nr_req_wr, "write reqs completed, latencies in us: ",
> +		 lat_max_wr, lat_min_wr, lat_avg_wr, lat_sum_wr);
> +
> +print_usage:
> +	return scnprintf(buf, PAGE_SIZE, "%s\n%s",
> +			 "To start monitoring, echo 1 > monitor, cat monitor.",
> +			 "To stop monitoring, echo 0 > monitor.");

We do not have "help" files in sysfs output, sorry.

> +static struct attribute *ufs_qcom_sysfs_attrs[] = {
> +	&dev_attr_monitor.attr,
> +	NULL
> +};
> +
> +static const struct attribute_group ufs_qcom_sysfs_group = {
> +	.name = "qcom",

Why do you need a subdirectory?

> +	.attrs = ufs_qcom_sysfs_attrs,
> +};
> +
> +static int ufs_qcom_init_sysfs(struct ufs_hba *hba)
> +{
> +	int ret;
> +
> +	ret = sysfs_create_group(&hba->dev->kobj, &ufs_qcom_sysfs_group);

When you find yourself in a driver calling a sysfs_* function, something
is wrong.  Use the proper apis for having the file automatically added
when your driver binds to the device, the driver core will do this for
you.

Also, even if you did want to do this "manually", you forgot to remove
the files when the device is removed :(

thanks,

greg k-h