It is always helpful to have a test tool in place if we implement
new data critical algorithms. So add some test routines to the raid6
checker that can prove if the new xor_syndrome() works as expected.
Run through all permutations of start/stop pages per algorithm and
simulate a xor_syndrome() assisted rmw run. After each rmw check if
the recovery algorithm still confirms that the stripe is fine.
Signed-off-by: Markus Stockhausen <stockhausen@collogia.de>
Signed-off-by: NeilBrown <neilb@suse.de>
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.
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 <ken@tilera.com>
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
Signed-off-by: NeilBrown <neilb@suse.de>
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 <ard.biesheuvel@linaro.org>
Acked-by: Nicolas Pitre <nico@linaro.org>
Cc: hpa@linux.intel.com
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" <hpa@zytor.com>
Signed-off-by: Jim Kukunas <james.t.kukunas@linux.intel.com>
Signed-off-by: NeilBrown <neilb@suse.de>
