1disksort(9F) Kernel Functions for Drivers disksort(9F)
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6 disksort - single direction elevator seek sort for buffers
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9 #include <sys/conf.h>
10 #include <sys/ddi.h>
11 #include <sys/sunddi.h>
12 void
13 disksort(struct diskhd *dp, struct buf *bp);
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18 Solaris DDI specific (Solaris DDI).
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21 dp A pointer to a diskhd structure. A diskhd structure is essen‐
22 tially identical to head of a buffer structure (see buf(9S)). The
23 only defined items of interest for this structure are the av_forw
24 and av_back structure elements which are used to maintain the
25 front and tail pointers of the forward linked I/O request queue.
26 bp A pointer to a buffer structure. Typically this is the I/O
29 request that the driver receives in its strategy routine (see
30 strategy(9E)). The driver is responsible for initializing the
31 b_resid structure element to a meaningful sort key value prior to
32 calling disksort().
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36 The function disksort() sorts a pointer to a buffer into a single for‐
37 ward linked list headed by the av_forw element of the argument *dp.
38 It uses a one-way elevator algorithm that sorts buffers into the queue
41 in ascending order based upon a key value held in the argument buffer
42 structure element b_resid.
43 This value can either be the driver calculated cylinder number for the
46 I/O request described by the buffer argument, or simply the absolute
47 logical block for the I/O request, depending on how fine grained the
48 sort is desired to be or how applicable either quantity is to the
49 device in question.
50 The head of the linked list is found by use of the av_forw structure
53 element of the argument *dp. The tail of the linked list is found by
54 use of the av_back structure element of the argument *dp. The av_forw
55 element of the *bp argument is used by disksort() to maintain the for‐
56 ward linkage. The value at the head of the list presumably indicates
57 the currently active disk area.
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60 This function can be called from user, interrupt, or kernel context.
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63 strategy(9E), buf(9S)
64 Writing Device Drivers
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69 The disksort() function does no locking. Therefore, any locking is com‐
70 pletely the responsibility of the caller.
71SunOS 5.11 16 Jan 2006 disksort(9F)