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On Tue, May 20, 2014 at 06:23:40PM +0400, Konstantin Serebryany wrote: > Do you think such a benchmarks is possible at all? > I've made a simple test (attached) and profiled it with "perf": > 85.26% a.out libcrypt-2.15.so [.] _ufc_doit_r > 6.13% a.out libcrypt-2.15.so [.] _ufc_mk_keytab_r > 2.40% a.out libcrypt-2.15.so [.] _ufc_setup_salt_r > 1.56% a.out libcrypt-2.15.so [.] __crypt_r > 1.51% a.out libcrypt-2.15.so [.] _ufc_output_conversion_r > 1.35% a.out libcrypt-2.15.so [.] crypt > > As you can see, crypt_r itself takes a tiny fraction of time, > most of it is spent in _ufc_* which are defined in another module. > Any changes in crypt itself (unless you do something insane) will not > be observable in profile. You'll need to choose inputs so that __md5_crypt_r is called - crypt/crypt-entry.c should help you with that. if __md5_crypt_r takes a tiny fraction of time again, then this change should be safe, but I would prefer that the inputs get fed into the benchtests anyway so that we can automatically track performance of crypt for those inputs in future. Siddhesh
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