coccinelle: alloc_cast: drop removed allocatorsgrafted

- pci_alloc_consistent() and pci_zalloc_consistent() were removed by
  commit 7968778914e5
  ("PCI: Remove the deprecated "pci-dma-compat.h" API")

- kmem_alloc() was removed by commit f078d4ea8276
  ("xfs: convert kmem_alloc() to kmalloc()")

- kmem_zalloc() was removed by commit 10634530f7ba
  ("xfs: convert kmem_zalloc() to kzalloc()")

- kmem_zone_alloc() and kmem_zone_zalloc() were removed by commit
  bae633a4a283 ("xfs: remove xfs_zone_{alloc,zalloc} helpers")

So drop them from the rules.

No functional change.

Signed-off-by: Sang-Heon Jeon <ekffu200098@gmail.com>
Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>

1 files changed, 72 insertions, 0 deletions

diff --git a/Documentation/block/deadline-iosched.rst b/Documentation/block/deadline-iosched.rst
new file mode 100644
index 000000000..9f5c5a4c3
--- /dev/null
+++ b/Documentation/block/deadline-iosched.rst
@@ -0,0 +1,72 @@
+==============================
+Deadline IO scheduler tunables
+==============================
+
+This little file attempts to document how the deadline io scheduler works.
+In particular, it will clarify the meaning of the exposed tunables that may be
+of interest to power users.
+
+Selecting IO schedulers
+-----------------------
+Refer to Documentation/block/switching-sched.rst for information on
+selecting an io scheduler on a per-device basis.
+
+------------------------------------------------------------------------------
+
+read_expire	(in ms)
+-----------------------
+
+The goal of the deadline io scheduler is to attempt to guarantee a start
+service time for a request. As we focus mainly on read latencies, this is
+tunable. When a read request first enters the io scheduler, it is assigned
+a deadline that is the current time + the read_expire value in units of
+milliseconds.
+
+
+write_expire	(in ms)
+-----------------------
+
+Similar to read_expire mentioned above, but for writes.
+
+
+fifo_batch	(number of requests)
+------------------------------------
+
+Requests are grouped into ``batches`` of a particular data direction (read or
+write) which are serviced in increasing sector order.  To limit extra seeking,
+deadline expiries are only checked between batches.  fifo_batch controls the
+maximum number of requests per batch.
+
+This parameter tunes the balance between per-request latency and aggregate
+throughput.  When low latency is the primary concern, smaller is better (where
+a value of 1 yields first-come first-served behaviour).  Increasing fifo_batch
+generally improves throughput, at the cost of latency variation.
+
+
+writes_starved	(number of dispatches)
+--------------------------------------
+
+When we have to move requests from the io scheduler queue to the block
+device dispatch queue, we always give a preference to reads. However, we
+don't want to starve writes indefinitely either. So writes_starved controls
+how many times we give preference to reads over writes. When that has been
+done writes_starved number of times, we dispatch some writes based on the
+same criteria as reads.
+
+
+front_merges	(bool)
+----------------------
+
+Sometimes it happens that a request enters the io scheduler that is contiguous
+with a request that is already on the queue. Either it fits in the back of that
+request, or it fits at the front. That is called either a back merge candidate
+or a front merge candidate. Due to the way files are typically laid out,
+back merges are much more common than front merges. For some work loads, you
+may even know that it is a waste of time to spend any time attempting to
+front merge requests. Setting front_merges to 0 disables this functionality.
+Front merges may still occur due to the cached last_merge hint, but since
+that comes at basically 0 cost we leave that on. We simply disable the
+rbtree front sector lookup when the io scheduler merge function is called.
+
+
+Nov 11 2002, Jens Axboe <jens.axboe@oracle.com>