Attachment 115547 Details for Bug 157316 – devstat.9.diff

[patch] devstat.9.diff

devstat.9.diff (text/x-patch; charset=US-ASCII), 7.33 KB, created by pluknet on 2011-05-25 14:04:15 UTC

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Creator: pluknet

Created: 2011-05-25 14:04:15 UTC

Size: 7.33 KB

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obsolete

>Index: devstat.9
>===================================================================
>--- devstat.9	(revision 222032)
>+++ devstat.9	(working copy)
>@@ -27,23 +27,23 @@
> .\"
> .\" $FreeBSD$
> .\"
>-.Dd May 22, 1998
>+.Dd May 22, 2011
> .Dt DEVSTAT 9
> .Os
> .Sh NAME
> .Nm devstat ,
>-.Nm devstat_add_entry ,
> .Nm devstat_end_transaction ,
> .Nm devstat_end_transaction_bio ,
>+.Nm devstat_new_entry ,
> .Nm devstat_remove_entry ,
>-.Nm devstat_start_transaction
>+.Nm devstat_start_transaction ,
>+.Nm devstat_start_transaction_bio
> .Nd kernel interface for keeping device statistics
> .Sh SYNOPSIS
> .In sys/devicestat.h
>-.Ft void
>-.Fo devstat_add_entry
>-.Fa "struct devstat *ds"
>-.Fa "const char *dev_name"
>+.Ft "struct devstat *"
>+.Fo devstat_new_entry
>+.Fa "const void *dev_name"
> .Fa "int unit_number"
> .Fa "u_int32_t block_size"
> .Fa "devstat_support_flags flags"
>@@ -53,13 +53,17 @@
> .Ft void
> .Fn devstat_remove_entry "struct devstat *ds"
> .Ft void
>-.Fn devstat_start_transaction "struct devstat *ds"
>+.Fn devstat_start_transaction "struct devstat *ds" "struct bintime *now"
> .Ft void
>+.Fn devstat_start_transaction_bio "struct devstat *ds" "struct bio *bp"
>+.Ft void
> .Fo devstat_end_transaction
> .Fa "struct devstat *ds"
> .Fa "u_int32_t bytes"
> .Fa "devstat_tag_type tag_type"
> .Fa "devstat_trans_flags flags"
>+.Fa "struct bintime *now"
>+.Fa "struct bintime *then"
> .Fc
> .Ft void
> .Fo devstat_end_transaction_bio
>@@ -77,19 +81,14 @@
> code.
> Instead, that is left for user programs to handle.
> .Pp
>-.Fn devstat_add_entry
>+.Fn devstat_new_entry
> registers a device with the
> .Nm
>-subsystem.
>-The caller is expected to have already allocated \fBand zeroed\fR
>-the devstat structure before calling this function.
>-.Fn devstat_add_entry
>-takes several arguments:
>+subsystem and returns a pointer to the allocated and initialized
>+.Va devstat
>+structure.
>+It takes several arguments:
> .Bl -tag -width device_type
>-.It ds
>-The
>-.Va devstat
>-structure, allocated and zeroed by the client.
> .It dev_name
> The device name, e.g.\& da, cd, sa.
> .It unit_number
>@@ -127,7 +126,7 @@
> .Nm
> subsystem.
> It takes the devstat structure for the device in question as
>-an argument.
>+an argument and frees used memory back to the system.
> The
> .Nm
> generation number is incremented and the number of devices is decremented.
>@@ -136,18 +135,23 @@
> registers the start of a transaction with the
> .Nm
> subsystem.
>-The busy count is incremented with each transaction start.
>+The start count is incremented with each transaction start.
> When a device goes from idle to busy, the system uptime is recorded in the
>-.Va start_time
>+.Va busy_from
> field of the
> .Va devstat
> structure.
>+The caller can override the time value by specifying a non-NULL
>+timestamp argument
>+.Va now
>+to the function.
> .Pp
> .Fn devstat_end_transaction
> registers the end of a transaction with the
> .Nm
> subsystem.
>-It takes four arguments:
>+The end count is incremented with each transaction end.
>+It takes several arguments:
> .Bl -tag -width tag_type
> .It ds
> The
>@@ -161,12 +165,21 @@
> .It flags
> Transaction flags indicating whether the transaction was a read, write, or
> whether no data was transferred.
>+.It now
>+The current timestamp.
>+.It then
>+The timestamp of when this transaction started.
> .El
> .Pp
>+.Fn devstat_start_transaction_bio
>+and
> .Fn devstat_end_transaction_bio
>-is a wrapper for
>+are wrappers for
>+.Fn devstat_start_transaction
>+and
> .Fn devstat_end_transaction
>-which pulls all the information from a
>+respectively
>+which pull all the information from a
> .Va "struct bio"
> which is ready for biodone().
> .Pp
>@@ -201,68 +214,45 @@
> .It unit_number
> The unit number identifies the particular instance of the peripheral driver
> in question.
>-.It bytes_written
>-This is the number of bytes that have been written to the device.
>+.It bytes[flags]
>+This is the number of bytes that have been written, read or freed/erased on
>+the device according to a transaction type specified in flags index.
>+See below for transaction types.
> This number is currently an unsigned 64 bit integer.
> This will hopefully
> eliminate the counter wrap that would come very quickly on some systems if
> 32 bit integers were used.
>-.It bytes_read
>-This is the number of bytes that have been read from the device.
>-.It bytes_freed
>-This is the number of bytes that have been freed/erased on the device.
>-.It num_reads
>-This is the number of reads from the device.
>-.It num_writes
>-This is the number of writes to the device.
>-.It num_frees
>-This is the number of free/erase operations on the device.
>-.It num_other
>-This is the number of transactions to the device which are neither reads or
>-writes.
>-For instance,
>-.Tn SCSI
>-drivers often send a test unit ready command to
>-.Tn SCSI
>-devices.
>-The test unit ready command does not read or write any data.
>-It merely causes the device to return its status.
>-.It busy_count
>-This is the current number of outstanding transactions for the device.
>-This should never go below zero, and on an idle device it should be zero.
>-If either one of these conditions is not true, it indicates a problem in
>-the way
>+.It operations[flags]
>+This is the number of read, write or free/erase operations on the device
>+according to a transaction type specified in flags index.
>+.It duration[[flags]
>+The duration of read, write or free/erase operations on the device
>+according to a transaction type specified in flags index.
>+.It start_count , end_count
>+This are numbers of started and completed transactions for the device,
>+which are updated in the
> .Fn devstat_start_transaction
> and
> .Fn devstat_end_transaction
>-are being called in client code.
>-There should be one and only one
>-transaction start event and one transaction end event for each transaction.
>+paths respectively.
>+On an idle device their values should be equal.
> .It block_size
> This is the block size of the device, if the device has a block size.
> .It tag_types
> This is an array of counters to record the number of various tag types that
> are sent to a device.
> See below for a list of tag types.
>-.It dev_creation_time
>+.It creation_time
> This is the time, as reported by
>-.Fn getmicrotime
>+.Fn binuptime
> that the device was registered.
> .It busy_time
>-This is the amount of time that the device busy count has been greater than
>-zero.
>-This is only updated when the busy count returns to zero.
>-.It start_time
>-This is the time, as reported by
>-.Fn getmicrouptime
>-that the device busy count went from zero to one.
>-.It last_comp_time
>-This is the time as reported by
>-.Fn getmicrouptime
>-that a transaction last completed.
>-It is used along with
>-.Va start_time
>-to calculate the device busy time.
>+This is the amount of time that the device was busy.
>+This is only updated during the ending of a transaction.
>+.It busy_from
>+This is the system time, as reported by
>+.Xr binuptime
>+when starting a transaction of a device that goes from idle to busy.
> .It flags
> These flags indicate which statistics measurements are supported by a
> particular device.
>@@ -378,8 +368,19 @@
> 	DEVSTAT_WRITE	= 0x02,
> 	DEVSTAT_FREE	= 0x03
> } devstat_trans_flags;
>+#define	DEVSTAT_N_TRANS_FLAGS	4
> .Ed
> .Pp
>+DEVSTAT_NO_DATA is a type of transactions to the device which are neither
>+reads or writes.
>+For instance,
>+.Tn SCSI
>+drivers often send a test unit ready command to
>+.Tn SCSI
>+devices.
>+The test unit ready command does not read or write any data.
>+It merely causes the device to return its status.
>+.Pp
> There are four possible values for the
> .Va tag_type
> argument to

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