Re: af_alg: Add ability to use Linux kernel crypto API on data in memory

[Matteo Croce]

On Sun, May 6, 2018 at 6:01 PM, Bruno Haible <address@hidden> wrote:
> Now, here's a draft patch for adding support for AF_ALG also for the
> sha1_buffer etc. functions.
>
> But I have a problem here: On 4 different systems, I don't get a speedup
> from this patch.
>
> To benchmark it, I use this set of commands:
>
> $ ./gnulib-tool --create-testdir --dir=testdir --single-configure --symlink 
> crypto/md5 crypto/sha1 crypto/sha256 crypto/sha512
> $ cd testdir
> $ mkdir without; (cd without; ../configure CPPFLAGS=-Wall CFLAGS=-O2 
> --without-linux-crypto; make && make check)
> $ mkdir with; (cd with; ../configure CPPFLAGS=-Wall CFLAGS=-O2 
> --with-linux-crypto; make && make check)
>
> $ without/gltests/bench-md5 100 1000000
> real   0.391257
> user   0.388
> sys    0.004
> $ with/gltests/bench-md5 100 1000000
> real   9.800789
> user   1.088
> sys    8.648
> $ without/gltests/bench-md5 1000 100000
> real   0.289286
> user   0.288
> sys    0.000
> $ with/gltests/bench-md5 1000 100000
> real   1.220016
> user   0.104
> sys    1.116
> $ without/gltests/bench-md5 10000 10000
> real   0.270131
> user   0.268
> sys    0.000
> $ with/gltests/bench-md5 10000 10000
> real   0.375399
> user   0.020
> sys    0.352
> $ without/gltests/bench-md5 100000 1000
> real   0.280091
> user   0.276
> sys    0.000
> $ with/gltests/bench-md5 100000 1000
> real   0.295650
> user   0.000
> sys    0.292
> $ without/gltests/bench-md5 100000 1000
> real   0.276514
> user   0.276
> sys    0.000
> $ with/gltests/bench-md5 100000 1000
> real   0.292350
> user   0.000
> sys    0.292
> $ without/gltests/bench-md5 1000000 100
> real   0.261845
> user   0.260
> sys    0.004
> $ with/gltests/bench-md5 1000000 100
> real   0.265650
> user   0.000
> sys    0.260
> [and similarly for sha1 etc.]
>
> Tested this on
>   - Intel Xeon X5450
>   - Intel Xeon E5-2603 v3
>   - Intel Core i7-2600
>   - Intel Core m3-6Y30
> On all four, no speedup is visible.
>
> On machines without crypto instructions or crypto devices, I would expect
> that
>   - sha1_stream gets slightly faster with than without linux-crypto
>     (because the copy of data from the file to user-space is optimized away).
>   - sha1_buffer is slightly slower with than without linux-crypto
>     (because of the overhead of copying the data from user to kernel space).
>
> Whereas on machines with crypto instructions or crypto devices, I would
> expect a significant benefit for both functions.
>
> You showed us significant benefits for sha1_stream, whereas I see no benefit
> for sha1_buffer. How is this possible?
>
> In <https://en.wikipedia.org/wiki/AES_instruction_set> I read that there are
> specialized instructions for AES. Does it mean that there are NO specialized
> instructions for MD5, SHA-1, SHA-224 ... SHA-512? In this case, all the work
> we have done is futile for Intel CPUs and only beneficial for embedded CPUs??
>
> Can you try this comparison on the Intel Xeon you have access to, please?
>
> Bruno

Hi Bruno,

I've checked out latest gnulib, and after double checking that commit
761523ddea70f0456b556c09868910686751fff5 was there I ran this:

address@hidden:~/src/gnulib/testdir$ strace -e trace=%network
with/gltests/bench-md5 10000000 100
real   1.138617
user   1.139
sys    0.000
+++ exited with 0 +++
address@hidden:~/src/gnulib/testdir$ strace -e trace=%network
with/gltests/bench-sha1 10000000 100
real   1.259929
user   1.260
sys    0.000
+++ exited with 0 +++

It seems that kernel API are not used in this test, or I'm running
them the wrong way?

-- 
Matteo Croce
per aspera ad upstream