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    SubjectRe: [PATCH] zfcp: add some internal zfcp adapter statistics

    On Wed, 2007-10-31 at 11:33 +0100, Swen Schillig wrote:
    > From: Swen Schillig <>
    > add some statistics provided by the zFCP adapter to the sysfs
    > The new zFCP adapter statistics provide a variety of information
    > about the virtual adapter (subchannel). In order to collect this information
    > the zFCP driver is extended on one side to query the adapter and
    > on the other side summarize certain values which can then be fetched on demand.
    > This information is made available via files(attributes) in the sysfs filesystem.
    > The information provided by the new zFCP adapter statistics can be fetched
    > by reading from the following files in the sysfs filesystem
    > /sys/class/scsi_host/host<n>/seconds_active
    > /sys/class/scsi_host/host<n>/requests
    > /sys/class/scsi_host/host<n>/megabytes
    > /sys/class/scsi_host/host<n>/utilization

    This lot all look like they belong in the FC transport class statistics
    (some even already exist there).

    > These are the statistics on a virtual adapter (subchannel) level.
    > In addition latency information is provided on a SCSI device level (LUN) which
    > can be found at the following location
    > /sys/class/scsi_device/<H:C:T:L>/device/cmd_latency
    > /sys/class/scsi_device/<H:C:T:L>/device/read_latency
    > /sys/class/scsi_device/<H:C:T:L>/device/write_latency

    These look to duplicate to some degree the figures
    in /sys/block/<dev>/stat. Isn't the block device the best place to
    gather these, if they're useful? Since user latencies should probably
    include elevator times.


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