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Rework of fletcher_4 module

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- Benchmark memory block is increased to 128kiB to reflect real block sizes more
accurately. Measurements include all three stages needed for checksum generation,
i.e. `init()/compute()/fini()`. The inner loop is repeated multiple times to offset
overhead of time function.

- Fastest implementation selects native and byteswap methods independently in
benchmark. To support this new function pointers `init_byteswap()/fini_byteswap()`
are introduced.

- Implementation mutex lock is replaced by atomic variable.

- To save time, benchmark is not executed in userspace. Instead, highest supported
implementation is used for fastest. Default userspace selector is still 'cycle'.

- `fletcher_4_native/byteswap()` methods use incremental methods to finish
calculation if data size is not multiple of vector stride (currently 64B).

- Added `fletcher_4_native_varsize()` special purpose method for use when buffer size
is not known in advance. The method does not enforce 4B alignment on buffer size, and
will ignore last (size % 4) bytes of the data buffer.

- Benchmark `kstat` is changed to match the one of vdev_raidz. It now shows
throughput for all supported implementations (in B/s), native and byteswap,
as well as the code [fastest] is running.

Example of `fletcher_4_bench` running on `Intel(R) Xeon(R) CPU E5-2660 v3 @ 2.60GHz`:
implementation   native         byteswap
scalar           4768120823     3426105750
sse2             7947841777     4318964249
ssse3            7951922722     6112191941
avx2             13269714358    11043200912
fastest          avx2           avx2

Example of `fletcher_4_bench` running on `Intel(R) Xeon Phi(TM) CPU 7210 @ 1.30GHz`:
implementation   native         byteswap
scalar           1291115967     1031555336
sse2             2539571138     1280970926
ssse3            2537778746     1080016762
avx2             4950749767     1078493449
avx512f          9581379998     4010029046
fastest          avx512f        avx512f

Signed-off-by: Gvozden Neskovic <neskovic@gmail.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #4952
This commit is contained in:
Gvozden Neskovic
2016-07-12 17:50:54 +02:00
committed by Brian Behlendorf
parent 70b258fc96
commit fc897b24b2
7 changed files with 385 additions and 191 deletions
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module/zcommon/zfs_fletcher_intel.c
+6 -4
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@@ -92,7 +92,7 @@ fletcher_4_avx2_fini(zio_cksum_t *zcp)
}
static void
fletcher_4_avx2(const void *buf, uint64_t size, zio_cksum_t *unused)
fletcher_4_avx2_native(const void *buf, uint64_t size, zio_cksum_t *unused)
{
const uint64_t *ip = buf;
const uint64_t *ipend = (uint64_t *)((uint8_t *)ip + size);
@@ -137,9 +137,11 @@ static boolean_t fletcher_4_avx2_valid(void)
}
const fletcher_4_ops_t fletcher_4_avx2_ops = {
.init = fletcher_4_avx2_init,
.fini = fletcher_4_avx2_fini,
.compute = fletcher_4_avx2,
.init_native = fletcher_4_avx2_init,
.fini_native = fletcher_4_avx2_fini,
.compute_native = fletcher_4_avx2_native,
.init_byteswap = fletcher_4_avx2_init,
.fini_byteswap = fletcher_4_avx2_fini,
.compute_byteswap = fletcher_4_avx2_byteswap,
.valid = fletcher_4_avx2_valid,
.name = "avx2"