Timings.

[openssl.git] / crypto / bn / bn_exp.c

diff --git a/crypto/bn/bn_exp.c b/crypto/bn/bn_exp.c
index e6b3a5f5f97ad45f9576a1b268cc4c60b819f687..eab394b96231051d0dc5070dd679142f3ceca8f9 100644 (file)
--- a/crypto/bn/bn_exp.c
+++ b/crypto/bn/bn_exp.c
@@ -169,12 +169,25 @@ int BN_mod_exp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p, const BIGNUM *m,
         * exponentiation using the reciprocal-based quick remaindering
         * algorithm is used.
         *
-        * (For computations  a^p mod m  where  a, p, m  are of the same
-        * length, BN_mod_exp_recp takes roughly 50 .. 70 % the time
-        * required by the standard algorithm, and BN_mod_exp takes
-        * about 33 .. 40 % of it.
-        * [Timings obtained with expspeed.c on a AMD K6-2 platform under Linux,
-        * with various OpenSSL debugging macros defined.  YMMV.])
+        * (Timing obtained with expspeed.c [computations  a^p mod m
+        * where  a, p, m  are of the same length: 256, 512, 1024, 2048,
+        * 4096, 8192 bits], compared to the running time of the
+        * standard algorithm:
+        *
+        *   BN_mod_exp_mont   33 .. 40 %  [AMD K6-2, Linux, debug configuration]
+         *                     55 .. 77 %  [UltraSparc processor, but
+        *                                  debug-solaris-sparcv8-gcc conf.]
+        * 
+        *   BN_mod_exp_recp   50 .. 70 %  [AMD K6-2, Linux, debug configuration]
+        *                     62 .. 118 % [UltraSparc, debug-solaris-sparcv8-gcc]
+        *
+        * On the Sparc, BN_mod_exp_recp was faster than BN_mod_exp_mont
+        * at 2048 and more bits, but at 512 and 1024 bits, it was
+        * slower even than the standard algorithm!
+        *
+        * "Real" timings [linux-elf, solaris-sparcv9-gcc configurations]
+        * should be obtained when the new Montgomery reduction code
+        * has been integrated into OpenSSL.)
         */
 
 #define MONT_MUL_MOD