Alexey Serbin has uploaded a new patch set (#2).
Change subject: [rpc] faster generation of KRPC call ID
......................................................................
[rpc] faster generation of KRPC call ID
Updated the way how the KRPC call identifiers are generated.
To compare, I used the following code (headers are omitted):
old.cc:
-------------------------
int32_t cur_id = 0;
int32_t next_id() {
if (PREDICT_FALSE(cur_id == std::numeric_limits<int32_t>::max())) {
cur_id = 0;
} else {
++cur_id;
}
return cur_id;
}
int main() {
srandom(time(nullptr));
const int u_bound = 800000000 + (random() % 100);
int n = 0;
for (int i = 0; i < u_bound; ++i) {
n = next_id();
}
cout << n << endl;
return 0;
}
-------------------------
new.cc:
-------------------------
int32_t cur_id = 0;
int32_t next_id() {
++cur_id;
return (cur_id & 0x7fffffff);
}
int main() {
srandom(time(nullptr));
const int u_bound = 800000000 + (random() % 100);
int n = 0;
for (int i = 0; i < u_bound; ++i) {
n = next_id();
}
std::cout << n << std::endl;
return 0;
}
-------------------------
My ad-hoc measurements show that the new version is faster even if
compiling both with -O3 optimization flag:
old:
real 0m0.831s
user 0m0.822s
sys 0m0.005s
new:
real 0m0.005s
user 0m0.001s
sys 0m0.002s
>From the 'perf stat' perspective it looks good as well:
-------------------------
Performance counter stats for './old' (10 runs):
790.584545 task-clock # 1.001 CPUs utilized
1 context-switches # 0.002 K/sec
1 cpu-migrations # 0.001 K/sec
273 page-faults # 0.345 K/sec
2,583,562,591 cycles # 3.268 GHz
2,805,308,074 instructions # 1.09 insns per cycle
200,917,139 branches # 254.137 M/sec
13,513 branch-misses # 0.01% of all branches
0.790023494 seconds time elapsed
-------------------------
-------------------------
Performance counter stats for './new' (10 runs):
0.888215 task-clock # 0.831 CPUs utilized
0 context-switches # 0.000 K/sec
0 cpu-migrations # 0.000 K/sec
273 page-faults # 0.307 M/sec
2,561,042 cycles # 2.883 GHz
2,804,468 instructions # 1.10 insns per cycle
480,394 branches # 540.853 M/sec
11,575 branch-misses # 2.41% of all branches
0.001068744 seconds time elapsed
-------------------------
Change-Id: I03726343d222bcd241c2c2a5a1670a672f8e5cb6
---
M src/kudu/rpc/connection.cc
M src/kudu/rpc/connection.h
2 files changed, 9 insertions(+), 12 deletions(-)
git pull ssh://gerrit.cloudera.org:29418/kudu refs/changes/13/7813/2
--
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Gerrit-MessageType: newpatchset
Gerrit-Change-Id: I03726343d222bcd241c2c2a5a1670a672f8e5cb6
Gerrit-PatchSet: 2
Gerrit-Project: kudu
Gerrit-Branch: master
Gerrit-Owner: Alexey Serbin <aser...@cloudera.com>
Gerrit-Reviewer: Adar Dembo <a...@cloudera.com>
Gerrit-Reviewer: Kudu Jenkins
Gerrit-Reviewer: Todd Lipcon <t...@apache.org>
