linux-toradex.git/include/linux/raid, branch v4.6-rc6

raid6/algos.c : bug fix : Add the missing definitions to the pq.h file

2016-01-21T22:47:08+00:00

Adding these pr_info and pr_err definitions so as to allow code to be
compiled successfully for testing in userspace, since the printk has
been replaced by pr_info and pr_err in algos.c

Absence of these definitions result in the compilation errors
such as ' undefined reference to `pr_info' ' ' undefined reference to
`pr_err' '

Cc: NeilBrown 
Cc: Anton Blanchard 
Cc: Fenghua Yu 
Signed-off-by: Gayatri Kammela 
Signed-off-by: Shaohua Li

md/raid6 algorithms: delta syndrome functions

2015-04-21T22:00:41+00:00

v3: s-o-b comment, explanation of performance and descision for
the start/stop implementation

Implementing rmw functionality for RAID6 requires optimized syndrome
calculation. Up to now we can only generate a complete syndrome. The
target P/Q pages are always overwritten. With this patch we provide
a framework for inplace P/Q modification. In the first place simply
fill those functions with NULL values.

xor_syndrome() has two additional parameters: start & stop. These
will indicate the first and last page that are changing during a
rmw run. That makes it possible to avoid several unneccessary loops
and speed up calculation. The caller needs to implement the following
logic to make the functions work.

1) xor_syndrome(disks, start, stop, ...): "Remove" all data of source
blocks inside P/Q between (and including) start and end.

2) modify any block with start <= block <= stop

3) xor_syndrome(disks, start, stop, ...): "Reinsert" all data of
source blocks into P/Q between (and including) start and end.

Pages between start and stop that won't be changed should be filled
with a pointer to the kernel zero page. The reasons for not taking NULL
pages are:

1) Algorithms cross the whole source data line by line. Thus avoid
additional branches.

2) Having a NULL page avoids calculating the XOR P parity but still
need calulation steps for the Q parity. Depending on the algorithm
unrolling that might be only a difference of 2 instructions per loop.

The benchmark numbers of the gen_syndrome() functions are displayed in
the kernel log. Do the same for the xor_syndrome() functions. This
will help to analyze performance problems and give an rough estimate
how well the algorithm works. The choice of the fastest algorithm will
still depend on the gen_syndrome() performance.

With the start/stop page implementation the speed can vary a lot in real
life. E.g. a change of page 0 & page 15 on a stripe will be harder to
compute than the case where page 0 & page 1 are XOR candidates. To be not
to enthusiatic about the expected speeds we will run a worse case test
that simulates a change on the upper half of the stripe. So we do:

1) calculation of P/Q for the upper pages

2) continuation of Q for the lower (empty) pages

Signed-off-by: Markus Stockhausen 
Signed-off-by: NeilBrown

Merge tag 'md/3.12' of git://neil.brown.name/md

2013-09-10T20:03:41+00:00

Pull md update from Neil Brown:
 "Headline item is multithreading for RAID5 so that more IO/sec can be
  supported on fast (SSD) devices.  Also TILE-Gx SIMD suppor for RAID6
  calculations and an assortment of bug fixes"

* tag 'md/3.12' of git://neil.brown.name/md:
  raid5: only wakeup necessary threads
  md/raid5: flush out all pending requests before proceeding with reshape.
  md/raid5: use seqcount to protect access to shape in make_request.
  raid5: sysfs entry to control worker thread number
  raid5: offload stripe handle to workqueue
  raid5: fix stripe release order
  raid5: make release_stripe lockless
  md: avoid deadlock when dirty buffers during md_stop.
  md: Don't test all of mddev->flags at once.
  md: Fix apparent cut-and-paste error in super_90_validate
  raid6/test: replace echo -e with printf
  RAID: add tilegx SIMD implementation of raid6
  md: fix safe_mode buglet.
  md: don't call md_allow_write in get_bitmap_file.

RAID: add tilegx SIMD implementation of raid6

2013-08-27T06:05:50+00:00

This change adds TILE-Gx SIMD instructions to the software raid
(md), modeling the Altivec implementation. This is only for Syndrome
generation; there is more that could be done to improve recovery,
as in the recent Intel SSE3 recovery implementation.

The code unrolls 8 times; this turns out to be the best on tilegx
hardware among the set 1, 2, 4, 8 or 16.  The code reads one
cache-line of data from each disk, stores P and Q then goes to the
next cache-line.

The test code in sys/linux/lib/raid6/test reports 2008 MB/s data
read rate for syndrome generation using 18 disks (16 data and 2
parity). It was 1512 MB/s before this SIMD optimizations. This is
running on 1 core with all the data in cache.

This is based on the paper The Mathematics of RAID-6.
(http://kernel.org/pub/linux/kernel/people/hpa/raid6.pdf).

Signed-off-by: Ken Steele 
Signed-off-by: Chris Metcalf 
Signed-off-by: NeilBrown

lib/raid6: add ARM-NEON accelerated syndrome calculation

2013-07-08T21:09:18+00:00

Rebased/reworked a patch contributed by Rob Herring that uses
NEON intrinsics to perform the RAID-6 syndrome calculations.
It uses the existing unroll.awk code to generate several
unrolled versions of which the best performing one is selected
at boot time.

Signed-off-by: Ard Biesheuvel 
Acked-by: Nicolas Pitre 
Cc: hpa@linux.intel.com

UAPI: Remove empty Kbuild files

2013-01-03T01:36:10+00:00

Empty files can get deleted by the patch program, so remove empty Kbuild
files and their links from the parent Kbuilds.

Signed-off-by: David Howells 
Signed-off-by: Linus Torvalds

lib/raid6: Add AVX2 optimized gen_syndrome functions

2012-12-13T08:51:03+00:00

Add AVX2 optimized gen_syndrom functions, which is simply based on
sse2.c written by hpa.

Signed-off-by: Yuanhan Liu 
Reviewed-by: H. Peter Anvin 
Signed-off-by: Jim Kukunas 
Signed-off-by: NeilBrown

lib/raid6: Add AVX2 optimized recovery functions

2012-12-13T05:42:01+00:00

Optimize RAID6 recovery functions to take advantage of
the 256-bit YMM integer instructions introduced in AVX2.

The patch was tested and benchmarked before submission.
However hardware is not yet released so benchmark numbers
cannot be reported.

Acked-by: "H. Peter Anvin" 
Signed-off-by: Jim Kukunas 
Signed-off-by: NeilBrown

UAPI: (Scripted) Disintegrate include/linux/raid

2012-10-09T08:49:02+00:00

Signed-off-by: David Howells 
Acked-by: Arnd Bergmann 
Acked-by: Thomas Gleixner 
Acked-by: Michael Kerrisk 
Acked-by: Paul E. McKenney 
Acked-by: Dave Jones

lib/raid6: Add SSSE3 optimized recovery functions

2012-05-22T03:54:18+00:00

Add SSSE3 optimized recovery functions, as well as a system
for selecting the most appropriate recovery functions to use.

Originally-by: H. Peter Anvin 
Signed-off-by: Jim Kukunas 
Signed-off-by: NeilBrown