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* [dpdk-dev] [PATCH v2 0/5] vhost: I-cache pressure optimizations
@ 2019-05-17 15:06 Maxime Coquelin
  2019-05-17 15:06 ` [dpdk-dev] [PATCH v2 1/5] vhost: un-inline dirty pages logging functions Maxime Coquelin
                   ` (4 more replies)
  0 siblings, 5 replies; 12+ messages in thread
From: Maxime Coquelin @ 2019-05-17 15:06 UTC (permalink / raw)
  To: dev, tiwei.bie, jfreimann, zhihong.wang, bruce.richardson,
	konstantin.ananyev, david.marchand
  Cc: Maxime Coquelin

Some OVS-DPDK PVP benchmarks show a performance drop
when switching from DPDK v17.11 to v18.11.

With the addition of packed ring layout support,
rte_vhost_enqueue_burst and rte_vhost_dequeue_burst
became very large, and only a part of the instructions
are executed (either packed or split ring used).

This series aims at improving the I-cache pressure,
first by un-inlining split and packed rings, but
also by moving parts considered as cold in dedicated
functions (dirty page logging, fragmented descriptors
buffer management added for CVE-2018-1059).

With the series applied, size of the enqueue and
dequeue split paths is reduced significantly:

+---------+--------------------+---------------------+
| Version | Enqueue split path |  Dequeue split path |
+---------+--------------------+---------------------+
| v19.05  | 16461B             | 25521B              |
| +series | 7286B              | 11285B              |
+---------+--------------------+---------------------+

Using perf tool to monitor iTLB-load-misses event
while doing PVP benchmark with testpmd as vswitch,
we can see the number of iTLB misses being reduced:

- v19.05:
# perf stat --repeat 10  -C 2,3  -e iTLB-load-miss -- sleep 10

 Performance counter stats for 'CPU(s) 2,3' (10 runs):

             2,438      iTLB-load-miss                                                ( +- 13.43% )

       10.00058928 +- 0.00000336 seconds time elapsed  ( +-  0.00% )

- +series:
# perf stat --repeat 10  -C 2,3  -e iTLB-load-miss -- sleep 10

 Performance counter stats for 'CPU(s) 2,3' (10 runs):

                55      iTLB-load-miss                                                ( +- 10.08% )

       10.00059466 +- 0.00000283 seconds time elapsed  ( +-  0.00% )

The series also force the inlining of some rte_memcpy
helpers, as by adding packed ring support, some of them
were not more inlined but embedded as functions in
the virtio_net object file, which was not expected.

Finally, the series simplifies the descriptors buffers
prefetching, by doing it in the recently introduced
descriptor buffer mapping function.

v2:
===
 - Fix checkpatch issue
 - Reset author for patch 5 (David)
 - Force non-inlining in patch 2 (David)
 - Fix typo in path 3 commit message (David)

Maxime Coquelin (5):
  vhost: un-inline dirty pages logging functions
  vhost: do not inline packed and split functions
  vhost: do not inline unlikely fragmented buffers code
  vhost: simplify descriptor's buffer prefetching
  eal/x86: force inlining of all memcpy and mov helpers

 .../common/include/arch/x86/rte_memcpy.h      |  18 +-
 lib/librte_vhost/vhost.c                      | 165 ++++++++++++++++++
 lib/librte_vhost/vhost.h                      | 164 ++---------------
 lib/librte_vhost/virtio_net.c                 | 143 +++++++--------
 4 files changed, 251 insertions(+), 239 deletions(-)

-- 
2.21.0


^ permalink raw reply	[flat|nested] 12+ messages in thread

end of thread, other threads:[~2019-05-29  8:06 UTC | newest]

Thread overview: 12+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-05-17 15:06 [dpdk-dev] [PATCH v2 0/5] vhost: I-cache pressure optimizations Maxime Coquelin
2019-05-17 15:06 ` [dpdk-dev] [PATCH v2 1/5] vhost: un-inline dirty pages logging functions Maxime Coquelin
2019-05-20  5:18   ` Tiwei Bie
2019-05-17 15:06 ` [dpdk-dev] [PATCH v2 2/5] vhost: do not inline packed and split functions Maxime Coquelin
2019-05-20  5:30   ` Tiwei Bie
2019-05-17 15:06 ` [dpdk-dev] [PATCH v2 3/5] vhost: do not inline unlikely fragmented buffers code Maxime Coquelin
2019-05-20  5:51   ` Tiwei Bie
2019-05-24 13:50     ` Maxime Coquelin
2019-05-17 15:06 ` [dpdk-dev] [PATCH v2 4/5] vhost: simplify descriptor's buffer prefetching Maxime Coquelin
2019-05-29  8:05   ` Tiwei Bie
2019-05-17 15:06 ` [dpdk-dev] [PATCH v2 5/5] eal/x86: force inlining of all memcpy and mov helpers Maxime Coquelin
2019-05-20  8:30   ` David Marchand

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