Commit Graph

6 Commits

Author SHA1 Message Date
Dan Williams
162b96e63e ioat2,3: cacheline align software descriptor allocations
All the necessary fields for handling an ioat2,3 ring entry can fit into
one cacheline.  Move ->len prior to ->txd in struct ioat_ring_ent, and
move allocation of these entries to a hw-cache-aligned kmem cache to
reduce the number of cachelines dirtied for descriptor management.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2009-09-08 17:53:04 -07:00
Dan Williams
a309218ace ioat2,3: dynamically resize descriptor ring
Increment the allocation order of the descriptor ring every time we run
out of descriptors up to a maximum of allocation order specified by the
module parameter 'ioat_max_alloc_order'.  After each idle period
decrement the allocation order to a minimum order of
'ioat_ring_alloc_order' (i.e. the default ring size, tunable as a module
parameter).

Signed-off-by: Maciej Sosnowski <maciej.sosnowski@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2009-09-08 17:38:54 -07:00
Dan Williams
09c8a5b85e ioat: switch watchdog and reset handler from workqueue to timer
In order to support dynamic resizing of the descriptor ring or polling
for a descriptor in the presence of a hung channel the reset handler
needs to make progress while in a non-preemptible context.  The current
workqueue implementation precludes polling channel reset completion
under spin_lock().

This conversion also allows us to return to opportunistic cleanup in the
ioat2 case as the timer implementation guarantees at least one cleanup
after every descriptor is submitted.  This means the worst case
completion latency becomes the timer frequency (for exceptional
circumstances), but with the benefit of avoiding busy waiting when the
lock is contended.

Signed-off-by: Maciej Sosnowski <maciej.sosnowski@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2009-09-08 17:30:24 -07:00
Dan Williams
345d852391 ioat: ___devinit annotate the initialization paths
Mark all single use initialization routines with __devinit.

Signed-off-by: Maciej Sosnowski <maciej.sosnowski@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2009-09-08 17:30:24 -07:00
Dan Williams
6df9183a15 ioat: add some dev_dbg() calls
Provide some output for debugging the driver.

Signed-off-by: Maciej Sosnowski <maciej.sosnowski@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2009-09-08 17:30:23 -07:00
Dan Williams
5cbafa65b9 ioat2,3: convert to a true ring buffer
Replace the current linked list munged into a ring with a native ring
buffer implementation.  The benefit of this approach is reduced overhead
as many parameters can be derived from ring position with simple pointer
comparisons and descriptor allocation/freeing becomes just a
manipulation of head/tail pointers.

It requires a contiguous allocation for the software descriptor
information.

Since this arrangement is significantly different from the ioat1 chain,
move ioat2,3 support into its own file and header.  Common routines are
exported from driver/dma/ioat/dma.[ch].

Signed-off-by: Maciej Sosnowski <maciej.sosnowski@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2009-09-08 17:29:55 -07:00