> In my experience, it's not much the context switch by itself which causes
> performance degradation, but the fact that with threads, you have to put
> mutexes everywhere. And frankly, walking a list with locks everywhere
> is quite slower than doing it in one run at a rate of 3 or 4 cycles per
> entry. Also, local storage in function returns is not possible anymore,
> and some functions even need to malloc() instead of returning statically
> allocated data. I believe this is the reason for openssl being twice as
> slow when compiled thread-safe than in native mode.
I don't know where you got this idea from, but several experiments of mine
failed to confirm it. Here, for example, are two identical builds of
OpenSSL, one with 'threads' and one with 'no-threads'. Same compiler, same
other flags, same hardware (Linux 2.6.21.2, P3-1Ghz):
OpenSSL 0.9.8d 28 Sep 2006
built on: Wed May 30 00:55:25 PDT 2007
options:bn(64,32) md2(int) rc4(idx,int) des(ptr,risc1,16,long) aes(partial)
idea(int) blowfish(idx)
compiler:
gcc -DDSO_DLFCN -DHAVE_DLFCN_H -mcpu=pentium -DL_ENDIAN -DTERMIO -O3 -fomit-
frame-pointer -Wall -DOPENSSL_BN_ASM_PART_WORDS -DOPENSSL_IA32_SSE2 -DSHA1_A
SM -DMD5_ASM -DRMD160_ASM -DAES_ASM
available timing options: TIMES TIMEB HZ=100 [sysconf value]
timing function used: times
The 'numbers' are in 1000s of bytes per second processed.
type 16 bytes 64 bytes 256 bytes 1024 bytes 8192
bytes
md5 5295.13k 18837.99k 56614.66k 113037.65k
157575.85k
des cbc 21280.46k 22224.36k 22536.87k 22626.65k
22686.38k
sign verify sign/s verify/s
rsa 1024 bits 0.007653s 0.000381s 130.7 2626.1
OpenSSL 0.9.8d 28 Sep 2006
built on: Wed May 30 00:55:23 PDT 2007
options:bn(64,32) md2(int) rc4(idx,int) des(ptr,risc1,16,long) aes(partial)
idea(int) blowfish(idx)
compiler:
gcc -DOPENSSL_THREADS -D_REENTRANT -DDSO_DLFCN -DHAVE_DLFCN_H -mcpu=pentium
-DL_ENDIAN -DTERMIO -O3 -fomit-frame-pointer -Wall -DOPENSSL_BN_ASM_PART_WOR
DS -DOPENSSL_IA32_SSE2 -DSHA1_ASM -DMD5_ASM -DRMD160_ASM -DAES_ASM
available timing options: TIMES TIMEB HZ=100 [sysconf value]
timing function used: times
The 'numbers' are in 1000s of bytes per second processed.
type 16 bytes 64 bytes 256 bytes 1024 bytes 8192
bytes
md5 5355.29k 18880.64k 56515.93k 113145.51k
157908.99k
des cbc 21361.71k 22185.28k 22494.72k 22654.29k
22659.07k
sign verify sign/s verify/s
rsa 1024 bits 0.007612s 0.000380s 131.4 2629.5
DS
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