[stgt] [PATCH 1/2] Add infrastructure for statistics on SCSI device level

[FUJITA Tomonori]

Sorry for the delay,

On Wed, 20 Jun 2012 19:01:42 +0300
Alexander Nezhinsky <alexandern at mellanox.com> wrote:

> To introduce statistics on SCSI device level we need to accumulate them
> for each ITL (initiator-target-lun) nexus.
> 
> For example in case of iscsi, this is a granularity which is finer than
> a session (IT nexus), as it represents access to a specific lun within
> the session.
> 
> Statistics counters are added to the ITL object, "struct it_nexus_lu_info".
> They need to be shown later in various scopes (connection, device, target etc.)
> requiring two-way access, both from a device (lun to all its ITLs) and
> from an IT nexus (IT nexus to all its ITLs).
> 
> Thus a linked list's head called "it_nexus_lu_info_list" is added to both
> struct scsi_lu and struct it_nexus, while struct it_nexus_lu_info

Please use different names for each.

> becomes a memeber in these two lists, thru the entries called:
> itn_siblings and lu_siblings.
> 
> Signed-off-by: Alexander Nezhinsky <alexandern at mellanox.com>
> ---
>  usr/scsi.c   |   16 +++++++++++++-
>  usr/target.c |   67 +++++++++++++++++++++++++++++++++++++++------------------
>  usr/tgtd.h   |   27 ++++++++++++++++++++++-
>  3 files changed, 87 insertions(+), 23 deletions(-)
> 
> diff --git a/usr/scsi.c b/usr/scsi.c
> index 5ec3b4d..861d213 100644
> --- a/usr/scsi.c
> +++ b/usr/scsi.c
> @@ -201,6 +201,20 @@ int scsi_cmd_perform(int host_no, struct scsi_cmd *cmd)
>  	unsigned char op = cmd->scb[0];
>  	struct it_nexus_lu_info *itn_lu;
>  
> +	if (scsi_get_data_dir(cmd) == DATA_WRITE) {
> +		cmd->itn_lu_info->stat.wr_subm_sect += scsi_get_out_length(cmd) / 512;

I'm not still not sure about this. How about the case that the sector
size is not the multiple of 512? How about just using bytes?


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