linux-toradex.git/block/deadline-iosched.c, branch v3.4.57

block, cfq: move icq cache management to block core

2011-12-13T23:33:42+00:00

Let elevators set ->icq_size and ->icq_align in elevator_type and
elv_register() and elv_unregister() respectively create and destroy
kmem_cache for icq.

* elv_register() now can return failure.  All callers updated.

* icq caches are automatically named "ELVNAME_io_cq".

* cfq_slab_setup/kill() are collapsed into cfq_init/exit().

* While at it, minor indentation change for iosched_cfq.elevator_name
  for consistency.

This will help moving icq management to block core.  This doesn't
introduce any functional change.

Signed-off-by: Tejun Heo 
Signed-off-by: Jens Axboe

iosched: prevent aliased requests from starving other I/O

2011-06-02T19:19:05+00:00

Hi, Jens,

If you recall, I posted an RFC patch for this back in July of last year:
http://lkml.org/lkml/2010/7/13/279

The basic problem is that a process can issue a never-ending stream of
async direct I/Os to the same sector on a device, thus starving out
other I/O in the system (due to the way the alias handling works in both
cfq and deadline).  The solution I proposed back then was to start
dispatching from the fifo after a certain number of aliases had been
dispatched.  Vivek asked why we had to treat aliases differently at all,
and I never had a good answer.  So, I put together a simple patch which
allows aliases to be added to the rb tree (it adds them to the right,
though that doesn't matter as the order isn't guaranteed anyway).  I
think this is the preferred solution, as it doesn't break up time slices
in CFQ or batches in deadline.  I've tested it, and it does solve the
starvation issue.  Let me know what you think.

Cheers,
Jeff

Signed-off-by: Jeff Moyer 
Signed-off-by: Jens Axboe

block: remove per-queue plugging

2011-03-10T07:52:07+00:00

Code has been converted over to the new explicit on-stack plugging,
and delay users have been converted to use the new API for that.
So lets kill off the old plugging along with aops->sync_page().

Signed-off-by: Jens Axboe

block: convert to pos and nr_sectors accessors

2009-05-11T07:50:54+00:00

With recent cleanups, there is no place where low level driver
directly manipulates request fields.  This means that the 'hard'
request fields always equal the !hard fields.  Convert all
rq->sectors, nr_sectors and current_nr_sectors references to
accessors.

While at it, drop superflous blk_rq_pos() < 0 test in swim.c.

[ Impact: use pos and nr_sectors accessors ]

Signed-off-by: Tejun Heo 
Acked-by: Geert Uytterhoeven 
Tested-by: Grant Likely 
Acked-by: Grant Likely 
Tested-by: Adrian McMenamin 
Acked-by: Adrian McMenamin 
Acked-by: Mike Miller 
Cc: James Bottomley 
Cc: Bartlomiej Zolnierkiewicz 
Cc: Borislav Petkov 
Cc: Sergei Shtylyov 
Cc: Eric Moore 
Cc: Alan Stern 
Cc: FUJITA Tomonori 
Cc: Pete Zaitcev 
Cc: Stephen Rothwell 
Cc: Paul Clements 
Cc: Tim Waugh 
Cc: Jeff Garzik 
Cc: Jeremy Fitzhardinge 
Cc: Alex Dubov 
Cc: David Woodhouse 
Cc: Martin Schwidefsky 
Cc: Dario Ballabio 
Cc: David S. Miller 
Cc: Rusty Russell 
Cc: unsik Kim 
Cc: Laurent Vivier 
Signed-off-by: Jens Axboe

block: get rid of elevator_t typedef

2008-12-29T07:29:50+00:00

Just use struct elevator_queue everywhere instead.

Signed-off-by: Jens Axboe

deadline-iosched: non-functional fixes

2008-10-09T06:56:03+00:00

* convert goto to simpler while loop;
 * use rq_end_sector() instead of computing manually;
 * fix false comments;
 * remove spurious whitespace;
 * convert rq_rb_root macro to an inline function.

Signed-off-by: Aaron Carroll 
Signed-off-by: Jens Axboe

deadline-iosched: allow non-sequential batching

2008-10-09T06:56:02+00:00

Deadline currently only batches sector-contiguous requests, so except
for a few circumstances (e.g. requests in a single direction), it is
essentially first come first served.  This is bad for throughput, so
change it to CSCAN, which means requests in a batch do not need to be
sequential and are issued in increasing sector order.

Signed-off-by: Aaron Carroll 
Signed-off-by: Jens Axboe

block: let elv_register() return void

2007-12-18T07:29:28+00:00

elv_register() always returns 0, and there isn't anything it does where
it should return an error (the only error condition is so grave that
it's handled with a BUG_ON).

Signed-off-by: Adrian Bunk 
Signed-off-by: Jens Axboe

Deadline iosched: Fix batching fairness

2007-11-02T07:47:25+00:00

After switching data directions, deadline always starts the next batch
from the lowest-sector request.  This gives excessive deadline expiries
and large latency and throughput disparity between high- and low-sector
requests; an order of magnitude in some tests.

This patch changes the batching behaviour so new batches start from the
request whose expiry is earliest.

Signed-off-by: Aaron Carroll 
Signed-off-by: Jens Axboe

Deadline iosched: Reset batch for ordered requests

2007-11-02T07:47:25+00:00

The deadline I/O scheduler does not reset the batch count when starting
a new batch at a higher-sectored request.  This means the second and
subsequent batch in the same data direction will never exceed a single
request in size whenever higher-sectored requests are pending.

This patch gives new batches in the same data direction as old ones
their full quota of requests by resetting the batch count.

Signed-off-by: Aaron Carroll 
Signed-off-by: Jens Axboe