On 12/4/2014 19:57, Xuelei Fan wrote:
These are calls with SHA (i.e. SHA1) or SHA2 in the stack
(depth=4), and time for SHA2 vs SHA1 is 45.38% vs 1.09%.
Where is the other 98.91% cost for SHA1? You only call message digest
in the test, instinctively, shall most of the resources are cost by the
message digest, directly or indirectly?
The program call SHA2 and SHA1, they together spend 46% of time.
The other 54% is spent on file reading, unzip, char/string manipulation etc.
--Max
Xuelei
On 12/4/2014 12:09 PM, Wang Weijun wrote:
Hi All
I am comparing the difference of SHA-1 and SHA-256. First I wrote a JMH
benchmark:
@Benchmark
public void sig1(Blackhole bh) throws Exception {
bh.consume(sig("SHA-1"));
}
@Benchmark
public void sig2(Blackhole bh) throws Exception {
bh.consume(sig("SHA-256"));
}
byte[] sig(String alg) throws Exception {
MessageDigest md = MessageDigest.getInstance(alg);
md.update(new byte[10000]);
return md.digest();
}
The output is
Benchmark Mode Samples Score Error Units
o.o.b.Weird.sig1 thrpt 5 20984.435 ± 3356.455 ops/s
o.o.b.Weird.sig2 thrpt 5 13130.330 ± 976.824 ops/s
so the difference is there but not huge.
Then I wrote a simple app with
public static void main(String args[]) throws Exception {
int i = Arrays.hashCode(sig("SHA-1"));
i += Arrays.hashCode(sig("SHA-256"));
System.out.println(i);
}
static byte[] sig(String alg) throws Exception {
MessageDigest md = MessageDigest.getInstance(alg);
md.update(new byte[10000]);
return md.digest();
}
and then profile it with -agentlib:hprof=cpu=times, and get
SHA2 1 10.16% 10.16% 156 303276 sun.security.provider.SHA2.implCompress
SHA2 2 6.91% 17.07% 9984 303274 sun.security.provider.SHA2.lf_sigma0
SHA2 3 5.28% 22.36% 9984 303271 sun.security.provider.SHA2.lf_sigma1
SHA2 4 4.61% 26.96% 7488 303269 sun.security.provider.SHA2.lf_delta0
SHA2 5 4.20% 31.17% 29952 303273 sun.security.provider.SHA2.lf_S
SHA2 7 3.79% 39.16% 7488 303266 sun.security.provider.SHA2.lf_delta1
SHA2 9 2.85% 44.99% 29952 303270 sun.security.provider.SHA2.lf_S
SHA2 13 1.90% 54.47% 14976 303267 sun.security.provider.SHA2.lf_S
SHA2 17 1.49% 61.25% 14976 303264 sun.security.provider.SHA2.lf_S
SHA2 22 0.81% 66.12% 7488 303265 sun.security.provider.SHA2.lf_R
SHA2 23 0.81% 66.94% 9984 303275 sun.security.provider.SHA2.lf_maj
SHA2 25 0.81% 68.56% 156 303263
sun.security.provider.ByteArrayAccess.b2iBig64
SHA2 27 0.68% 70.05% 9984 303272 sun.security.provider.SHA2.lf_ch
SHA2 31 0.54% 72.63% 7488 303268 sun.security.provider.SHA2.lf_R
SHA1 34 0.54% 74.25% 156 303224 sun.security.provider.SHA.implCompress
SHA1 43 0.41% 78.05% 156 303223
sun.security.provider.ByteArrayAccess.b2iBig64
SHA2 60 0.27% 82.66% 2496 303262 java.lang.Integer.reverseBytes
SHA2 61 0.27% 82.93% 64 303290 sun.security.provider.SHA2.lf_sigma1
SHA1 116 0.14% 91.06% 2496 303222 java.lang.Integer.reverseBytes
These are calls with SHA (i.e. SHA1) or SHA2 in the stack (depth=4), and time
for SHA2 vs SHA1 is 45.38% vs 1.09%. With such a small app I don't think SHA or
SHA2 is called anywhere else. This is jdk9 b40.
Why is the output so different from JMH? Is it reasonable comparing them?
Thanks
Max
