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Subject[PATCH v3 0/9] padata: use unbound workqueues for parallel jobs
Date
v2 -> v3:
- Rebase onto cryptodev.

v1 -> v2:
- Updated patch 8 to avoid queueing the reorder work if the next object
by sequence number isn't ready yet (Herbert)
- Added Steffen's ack to all but patch 8 since that one changed.

RFC -> v1:
- Included Tejun's acks.
- Added testing section to cover letter.

Padata binds the parallel part of a job to a single CPU and round-robins
over all CPUs in the system for each successive job. Though the serial
parts rely on per-CPU queues for correct ordering, they're not necessary
for parallel work, and it improves performance to run the job locally on
NUMA machines and let the scheduler pick the CPU within a node on a busy
system.

This series makes parallel padata jobs run on unbound workqueues.

Patch Description
----- -----------

1 Make a padata instance allocate its workqueue internally.

2 Unconfine some recently-confined workqueue interfaces.

3-6 Address recursive CPU hotplug locking issue.

padata_alloc* requires its callers to hold this lock, but allocating
an unbound workqueue and calling apply_workqueue_attrs also take it.
Fix by removing the requirement for callers of padata_alloc*.

7-8 Add a second workqueue for each padata instance that's dedicated to
parallel jobs.

9 Small cleanup.

Performance
-----------

Measurements are from a 2-socket, 20-core, 40-CPU Xeon server.

For repeatability, modprobe was bound to a CPU and the serial cpumasks
for both pencrypt and pdecrypt were also restricted to a CPU different
from modprobe's.

# modprobe tcrypt alg="pcrypt(rfc4106(gcm(aes)))" type=3
# modprobe tcrypt mode=211 sec=1
# modprobe tcrypt mode=215 sec=1

Busy system (tcrypt run while 10 stress-ng tasks were burning 100% CPU)

base test
---------------- ---------------
speedup key_sz blk_sz ops/sec stdev ops/sec stdev

(pcrypt(rfc4106-gcm-aesni)) encryption (tcrypt mode=211)

117.2x 160 16 960 30 112555 24775
135.1x 160 64 845 246 114145 25124
113.2x 160 256 993 17 112395 24714
111.3x 160 512 1000 0 111252 23755
110.0x 160 1024 983 16 108153 22374
104.2x 160 2048 985 22 102563 20530
98.5x 160 4096 998 3 98346 18777
86.2x 160 8192 1000 0 86173 14480

(pcrypt(rfc4106-gcm-aesni)) decryption (tcrypt mode=211)

127.2x 160 16 997 5 126834 24244
128.4x 160 64 1000 0 128438 23261
127.6x 160 256 992 7 126627 23493
124.0x 160 512 1000 0 123958 22746
122.8x 160 1024 989 20 121372 22632
112.8x 160 2048 998 3 112602 18287
106.9x 160 4096 994 10 106255 16111
91.7x 160 8192 1000 0 91742 11670

multibuffer (pcrypt(rfc4106-gcm-aesni)) encryption (tcrypt mode=215)

242.2x 160 16 2363 141 572189 16846
242.1x 160 64 2397 151 580424 11923
231.1x 160 256 2472 21 571387 16364
237.6x 160 512 2429 24 577264 8692
238.3x 160 1024 2384 97 568155 6621
216.3x 160 2048 2453 74 530627 3480
209.2x 160 4096 2381 206 498192 19177
176.5x 160 8192 2323 157 410013 9903

multibuffer (pcrypt(rfc4106-gcm-aesni)) decryption (tcrypt mode=215)

220.3x 160 16 2341 228 515733 91317
216.6x 160 64 2467 33 534381 101262
217.7x 160 256 2451 45 533443 85418
213.8x 160 512 2485 26 531293 83767
211.0x 160 1024 2472 28 521677 80339
200.8x 160 2048 2459 67 493808 63587
188.8x 160 4096 2491 9 470325 58055
159.9x 160 8192 2459 51 393147 25756

Idle system (tcrypt run by itself)

base test
---------------- ---------------
speedup key_sz blk_sz ops/sec stdev ops/sec stdev

(pcrypt(rfc4106-gcm-aesni)) encryption (tcrypt mode=211)

2.5x 160 16 63412 43075 161615 1034
4.1x 160 64 39554 24006 161653 981
6.0x 160 256 26504 1436 160110 1158
6.2x 160 512 25500 40 157018 951
5.9x 160 1024 25777 1094 151852 915
5.8x 160 2048 24653 218 143756 508
5.6x 160 4096 24333 20 136752 548
5.0x 160 8192 23310 15 117660 481

(pcrypt(rfc4106-gcm-aesni)) decryption (tcrypt mode=211)

2.4x 160 16 53471 48279 128047 31328
3.4x 160 64 37712 20855 128187 31074
4.5x 160 256 27911 4378 126430 31084
4.9x 160 512 25346 175 123870 29099
3.1x 160 1024 38452 23118 120817 26846
4.7x 160 2048 24612 187 115036 23942
4.5x 160 4096 24217 114 109583 21559
4.2x 160 8192 23144 108 96850 16686

multibuffer (pcrypt(rfc4106-gcm-aesni)) encryption (tcrypt mode=215)

1.0x 160 16 412157 3855 426973 1591
1.0x 160 64 412600 4410 431920 4224
1.1x 160 256 410352 3254 453691 17831
1.2x 160 512 406293 4948 473491 39818
1.2x 160 1024 395123 7804 478539 27660
1.2x 160 2048 385144 7601 453720 17579
1.2x 160 4096 371989 3631 449923 15331
1.2x 160 8192 346723 1617 399824 18559

multibuffer (pcrypt(rfc4106-gcm-aesni)) decryption (tcrypt mode=215)

1.1x 160 16 407317 1487 452619 14404
1.1x 160 64 411821 4261 464059 23541
1.2x 160 256 408941 4945 477483 36576
1.2x 160 512 406451 611 472661 11038
1.2x 160 1024 394813 2667 456357 11452
1.2x 160 2048 390291 4175 448928 8957
1.2x 160 4096 371904 1068 449344 14225
1.2x 160 8192 344227 1973 404397 19540

Testing
-------

In addition to the bare metal performance runs above, this series was
tested in a kvm guest with the tcrypt module (mode=215). All
combinations of CPUs among parallel_cpumask, serial_cpumask, and CPU
hotplug online/offline were run with 3 possible CPUs, and over 2000
random combinations of these were run with 8 possible CPUs. Workqueue
events were used throughout to verify that all parallel and serial
workers executed on only the CPUs allowed by the cpumask sysfs files.

Finally, tcrypt mode=215 was run at each patch in the series when built
with and without CONFIG_PADATA/CONFIG_CRYPTO_PCRYPT.

v2: https://lore.kernel.org/linux-crypto/20190829173038.21040-1-daniel.m.jordan@oracle.com/
v1: https://lore.kernel.org/linux-crypto/20190813005224.30779-1-daniel.m.jordan@oracle.com/
RFC: https://lore.kernel.org/lkml/20190725212505.15055-1-daniel.m.jordan@oracle.com/

Daniel Jordan (9):
padata: allocate workqueue internally
workqueue: unconfine alloc/apply/free_workqueue_attrs()
workqueue: require CPU hotplug read exclusion for
apply_workqueue_attrs
padata: make padata_do_parallel find alternate callback CPU
pcrypt: remove padata cpumask notifier
padata, pcrypt: take CPU hotplug lock internally in
padata_alloc_possible
padata: use separate workqueues for parallel and serial work
padata: unbind parallel jobs from specific CPUs
padata: remove cpu_index from the parallel_queue

Documentation/padata.txt | 12 +--
crypto/pcrypt.c | 167 ++++---------------------------
include/linux/padata.h | 16 +--
include/linux/workqueue.h | 4 +
kernel/padata.c | 201 ++++++++++++++++++++++----------------
kernel/workqueue.c | 25 +++--
6 files changed, 170 insertions(+), 255 deletions(-)

--
2.23.0

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