https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59439
Jonathan Wakely <redi at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2018-09-26
Ever confirmed|0 |1
--- Comment #10 from Jonathan Wakely <redi at gcc dot gnu.org> ---
I have a patch that gets that down to:
snprintf
1 threads took 7 ms
2 threads took 7 ms
3 threads took 7 ms
4 threads took 7 ms
5 threads took 15 ms
6 threads took 16 ms
7 threads took 16 ms
8 threads took 16 ms
9 threads took 21 ms
10 threads took 22 ms
11 threads took 28 ms
12 threads took 23 ms
13 threads took 30 ms
14 threads took 30 ms
15 threads took 32 ms
16 threads took 32 ms
17 threads took 35 ms
18 threads took 38 ms
19 threads took 41 ms
20 threads took 40 ms
21 threads took 44 ms
22 threads took 48 ms
23 threads took 49 ms
24 threads took 50 ms
25 threads took 51 ms
26 threads took 54 ms
27 threads took 54 ms
28 threads took 56 ms
29 threads took 59 ms
30 threads took 60 ms
31 threads took 63 ms
iostream
1 threads took 29 ms
2 threads took 30 ms
3 threads took 31 ms
4 threads took 31 ms
5 threads took 59 ms
6 threads took 63 ms
7 threads took 64 ms
8 threads took 64 ms
9 threads took 82 ms
10 threads took 83 ms
11 threads took 99 ms
12 threads took 105 ms
13 threads took 112 ms
14 threads took 118 ms
15 threads took 123 ms
16 threads took 132 ms
17 threads took 140 ms
18 threads took 148 ms
19 threads took 162 ms
20 threads took 164 ms
21 threads took 174 ms
22 threads took 182 ms
23 threads took 194 ms
24 threads took 196 ms
25 threads took 210 ms
26 threads took 209 ms
27 threads took 220 ms
28 threads took 226 ms
29 threads took 234 ms
30 threads took 243 ms
31 threads took 252 ms
That's for 8 HT cores on Intel(R) Core(TM) i7-6700 CPU @ 3.40GHz
For 4 HT cores on Intel(R) Core(TM) i7-3520M CPU @ 2.90GHz the improvement is a
lot less impressive, going from current trunk's:
snprintf
1 threads took 17 ms
2 threads took 15 ms
...
31 threads took 186 ms
iostream
1 threads took 52 ms
2 threads took 105 ms
31 threads took 1430 ms
to:
snprintf
1 threads took 15 ms
2 threads took 12 ms
...
31 threads took 168 ms
iostream
1 threads took 47 ms
2 threads took 48 ms
...
31 threads took 675 ms
But that's still a significant improvement.
I'll finish testing and post to the mailing list.
