diff options
| author |   jaszha03 <jason.zhang2@arm.com> | 2019-07-01 17:08:57 -0500 |
|---|---|---|
| committer |   Florin Coras <florin.coras@gmail.com> | 2019-08-01 18:01:33 +0000 |
| commit | 30aaf97a90230d68c0f2736b0a026e07b06e7e32 (patch) | |
| tree | fcfa22ff97deab6c60be759f183b2fcab92c6210 /src/vnet | |
| parent | 691a3b7f11c41851d747e35c6bc5db9319d92c20 (diff) | |
vppinfra: refactor clib_rwlock_t to use single condition variable
Previous implementation of clib_rwlock_t used two spinlocks: one
writer lock, and one to guard the counter for the number of readers.
This implementation uses a single condition variable rw_cnt which
has the following properties:
if a writer has the rwlock, rw_cnt = -1
if the rwlock is free, rw_cnt = 0
otherwise, rw_cnt > 0 and rw_cnt = number of readers
rw_cnt will never be less than -1
Benchmarking:
The results below are the cycle counts from test_rwlock.c, configured so
that for 10000 iterations, 6 reader and 6 writer threads on separate cores
are spawned such that each writer thread increments a global counter
10000 times in each iteration. For Taishan, 4 reader and 4 writer
threads are spawned in each test.
x86 Xeon old rwlock: 12.473e8, 11.655e8, 13.201e8, 11.347e8, 13.182e8
x86 Xeon new rwlock: 5.881e8, 5.796e8, 6.536e8, 5.540e8, 5.890e8
Aarch64 ThX2* old rwlock: 9.263e7, 8.933e7, 9.074e7, 8.979e7, 9.378e7
Aarch64 ThX2* new rwlock: 7.221e7, 8.107e7, 7.515e7, 7.672e7, 7.386e7
A72 old rwlock: 3.268e6, 3.200e6, 3.086e6, 3.176e6, 3.170e6
A72 new rwlock: 1.261e6, 1.288e6, 1.251e6, 1.229e6, 1.234e6
*ThunderX2 used additional gcc options "-march=armv8.1-a+crc+crypto+lse"
Type: refactor
Change-Id: I7c347d3037b36205ab532cbcb52a374c846eb275
Signed-off-by: Jason Zhang <jason.zhang2@arm.com>
Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Reviewed-by: Lijian Zhang <Lijian.Zhang@arm.com>
Diffstat (limited to 'src/vnet')
| -rw-r--r-- | src/vnet/session/segment_manager.c | 1 |
1 files changed, 0 insertions, 1 deletions
diff --git a/src/vnet/session/segment_manager.c b/src/vnet/session/segment_manager.c index c0785695d4f..9c33e35e8f0 100644 --- a/src/vnet/session/segment_manager.c +++ b/src/vnet/session/segment_manager.c @@ -280,7 +280,6 @@ segment_manager_get_segment_w_lock (segment_manager_t * sm, u32 segment_index) void segment_manager_segment_reader_unlock (segment_manager_t * sm) { - ASSERT (sm->segments_rwlock->n_readers > 0); clib_rwlock_reader_unlock (&sm->segments_rwlock); } |