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author | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-10-16 13:09:16 -0400 |
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committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-10-16 13:09:16 -0400 |
commit | 92d15c2ccbb3e31a3fc71ad28fdb55e1319383c0 (patch) | |
tree | 8d83c0dc3c6b935d8367e331872f242b742f0a8a /Documentation/block/deadline-iosched.txt | |
parent | f20bf6125605acbbc7eb8c9420d7221c91aa83eb (diff) | |
parent | 644bd2f048972d75eb1979b1fdca257d528ce687 (diff) |
Merge branch 'for-linus' of git://git.kernel.dk/data/git/linux-2.6-block
* 'for-linus' of git://git.kernel.dk/data/git/linux-2.6-block: (63 commits)
Fix memory leak in dm-crypt
SPARC64: sg chaining support
SPARC: sg chaining support
PPC: sg chaining support
PS3: sg chaining support
IA64: sg chaining support
x86-64: enable sg chaining
x86-64: update pci-gart iommu to sg helpers
x86-64: update nommu to sg helpers
x86-64: update calgary iommu to sg helpers
swiotlb: sg chaining support
i386: enable sg chaining
i386 dma_map_sg: convert to using sg helpers
mmc: need to zero sglist on init
Panic in blk_rq_map_sg() from CCISS driver
remove sglist_len
remove blk_queue_max_phys_segments in libata
revert sg segment size ifdefs
Fixup u14-34f ENABLE_SG_CHAINING
qla1280: enable use_sg_chaining option
...
Diffstat (limited to 'Documentation/block/deadline-iosched.txt')
-rw-r--r-- | Documentation/block/deadline-iosched.txt | 25 |
1 files changed, 8 insertions, 17 deletions
diff --git a/Documentation/block/deadline-iosched.txt b/Documentation/block/deadline-iosched.txt index be08ffd1e9b8..c23cab13c3d1 100644 --- a/Documentation/block/deadline-iosched.txt +++ b/Documentation/block/deadline-iosched.txt | |||
@@ -5,16 +5,10 @@ This little file attempts to document how the deadline io scheduler works. | |||
5 | In particular, it will clarify the meaning of the exposed tunables that may be | 5 | In particular, it will clarify the meaning of the exposed tunables that may be |
6 | of interest to power users. | 6 | of interest to power users. |
7 | 7 | ||
8 | Each io queue has a set of io scheduler tunables associated with it. These | 8 | Selecting IO schedulers |
9 | tunables control how the io scheduler works. You can find these entries | 9 | ----------------------- |
10 | in: | 10 | Refer to Documentation/block/switching-sched.txt for information on |
11 | 11 | selecting an io scheduler on a per-device basis. | |
12 | /sys/block/<device>/queue/iosched | ||
13 | |||
14 | assuming that you have sysfs mounted on /sys. If you don't have sysfs mounted, | ||
15 | you can do so by typing: | ||
16 | |||
17 | # mount none /sys -t sysfs | ||
18 | 12 | ||
19 | 13 | ||
20 | ******************************************************************************** | 14 | ******************************************************************************** |
@@ -41,14 +35,11 @@ fifo_batch | |||
41 | 35 | ||
42 | When a read request expires its deadline, we must move some requests from | 36 | When a read request expires its deadline, we must move some requests from |
43 | the sorted io scheduler list to the block device dispatch queue. fifo_batch | 37 | the sorted io scheduler list to the block device dispatch queue. fifo_batch |
44 | controls how many requests we move, based on the cost of each request. A | 38 | controls how many requests we move. |
45 | request is either qualified as a seek or a stream. The io scheduler knows | ||
46 | the last request that was serviced by the drive (or will be serviced right | ||
47 | before this one). See seek_cost and stream_unit. | ||
48 | 39 | ||
49 | 40 | ||
50 | write_starved (number of dispatches) | 41 | writes_starved (number of dispatches) |
51 | ------------- | 42 | -------------- |
52 | 43 | ||
53 | When we have to move requests from the io scheduler queue to the block | 44 | When we have to move requests from the io scheduler queue to the block |
54 | device dispatch queue, we always give a preference to reads. However, we | 45 | device dispatch queue, we always give a preference to reads. However, we |
@@ -73,6 +64,6 @@ that comes at basically 0 cost we leave that on. We simply disable the | |||
73 | rbtree front sector lookup when the io scheduler merge function is called. | 64 | rbtree front sector lookup when the io scheduler merge function is called. |
74 | 65 | ||
75 | 66 | ||
76 | Nov 11 2002, Jens Axboe <axboe@suse.de> | 67 | Nov 11 2002, Jens Axboe <jens.axboe@oracle.com> |
77 | 68 | ||
78 | 69 | ||