In my last email I ran the benchmark on Fedora 21 (big mistake). Here are the
results when running it back on the 28/56 core RHEL 6.5 server showing
contention in a different place (fips). Is there a reason it would be calling
into the FIPS code to get a lock of FIPS is not enabled?
Contention log:
[Apr 24 21:35:09.731] Server {0x7f5529ccd700} ERROR: contention for lock -
total contention: 70662 waiting: 16 file: fips.c line: 471 type: 40
[Apr 24 21:35:09.732] Server {0x7f55299ca700} ERROR: contention for lock -
total contention: 71605 waiting: 2 file: fips.c line: 107 type: 39
Line in in fips that see the contention the most:
[bcall@bm77 trafficserver]$ grep fips.c diags.log | cut -f 19 -d ' ' | sort |
uniq -c | sort -rn
875379 471
288338 107
275472 127
Different lock types and their contention frequency (multiple benchmarks):
875379 40 < - in fips.c
563810 39 <- also in fips.c
440518 1
44145 18
17447 2
11356 10
1377 19
687 12
532 25
302 33
239 9
58 16
40 21
32 11
19 3
1 14
Code to diable FIPS and log:
#ifdef OPENSSL_FIPS
int mode = FIPS_mode();
Debug("ssl", "FIPS_mode: %d", mode);
mode = FIPS_mode();
if (mode) {
FIPS_mode_set(0);
Debug("ssl", "FIPS_mode: %d", mode);
}
#endif
[Apr 24 21:43:45.860] Server {0x7f7628146800} DEBUG: (ssl) FIPS_mode: 0
-Bryan
> On Apr 24, 2015, at 10:56 AM, John Foley <fol...@cisco.com
> <mailto:fol...@cisco.com>> wrote:
>
> When you create the private key given to SSL_CTX, be sure to instantiate a
> private key for each thread as well. If you share the same key across all
> threads, this can introduce contention.
>
> Here are the type 1 & 2 locks:
>
> # define CRYPTO_LOCK_ERR 1
> # define CRYPTO_LOCK_EX_DATA 2
>
> Have you checked the OpenSSL error log to see what errors are being generated?
>
> Also, if you disable FIPS, does the thread contention still occur?
>
>
>
> On 04/24/2015 01:36 PM, Bryan Call wrote:
>> We are using a single SSL_CTX across all the threads, so I will create
>> multiple SSL_CTX per thread. I implemented dynlock callbacks yesterday, but
>> I didn’t see them being used in the tests I did. I also added atomic
>> counters to see what type of locks are having contention (see logs below):
>>
>> Most of the lock contention seems to be around type 2 and type 1 locks when
>> calling our lock callback. In the FIPS/POST and SSL_CTX recommendations, in
>> your previous email, what types of locks would those help with?
>>
>> Log output:
>> [Apr 24 10:21:24.339] Server {0xb310000} ERROR: <SSLUtils.cc
>> <http://sslutils.cc/>:178 (SSL_locking_callback)> contention for lock -
>> total contention: 3938 waiting: 1 file:
>> /SourceCache/OpenSSL098/OpenSSL098-52.20.2/src/crypto/ex_data.c line: 496
>> type: 2
>> [Apr 24 10:21:24.754] Server {0xb10a000} ERROR: <SSLUtils.cc
>> <http://sslutils.cc/>:178 (SSL_locking_callback)> contention for lock -
>> total contention: 1350 waiting: 1 file:
>> /SourceCache/OpenSSL098/OpenSSL098-52.20.2/src/crypto/err/err_def.c line:
>> 343 type: 1
>>
>>
>> -Bryan
>>
>>
>>
>>
>>> On Apr 23, 2015, at 4:46 PM, John Foley <fol...@cisco.com
>>> <mailto:fol...@cisco.com>> wrote:
>>>
>>> Looking at your call stack, it appears you're testing with FIPS mode
>>> enabled. There's a lock in FIPS_selftest_failed() that's used to ensure
>>> the crypto algorithms inside the FIPS boundary are not utilized until after
>>> the POST has completed and passed. Unfortunately this lock remains
>>> installed for the lifetime of the process. We've seen thread contention in
>>> this area when using OpenSSL. One work-around is to modify your handler
>>> that you pass to SSL_locking_callback() to not lock when the lock ID is
>>> CRYPTO_LOCK_FIPS. But you would only want to disable this particular lock
>>> ID after the POST has completed.
>>>
>>> If the above doesn't help, another item to check is whether you're
>>> instantiating an SSL_CTX for each thread. I've seen some developers use a
>>> single SSL_CTX for multiple threads. This results in a single instance of
>>> the server cert and private key being shared across all the threads. This
>>> results in thread contention on the asymmetric key operations associated
>>> with the cert and private key (e.g. RSA). Be sure that each thread
>>> instantiates it's own SSL_CTX and certificate/private key.
>>>
>>> Lastly, add some debugs to count the locks by lock ID in your lock handler.
>>> There are about 40 different lock IDs defined in crypto/crypto.h. You'll
>>> need to identify which lock is causing the thread contention. Once you
>>> know that, then you can look in the code to see where that lock is used and
>>> troubleshoot from there.
>>>
>>>
>>>
>>> On 04/23/2015 07:23 PM, Bryan Call wrote:
>>>> I was running a benchmark on a 28 core (56 hyper-threaded) server that is
>>>> running 84 threads in the process and I am seeing a lot of lock
>>>> contention. I saw a lot of lock contention in the calls to
>>>> SSL_get_error() ssl3_accept(). I am running RHEL 6.5 and
>>>> openssl-1.0.1e-30.el6_6.7.x86_64. We have used SSL_locking_callback() to
>>>> setup pthread mutex locks, but haven’t setup dynlocks yet. Would dynlocks
>>>> help in this scenario?
>>>>
>>>>
>>>> Output from perf:
>>>> Samples: 1M of event 'cycles', Event count (approx.): 602783506611
>>>> - 48.04% [ET_NET 0] [kernel.kallsyms] [k] _spin_lock ◆
>>>> - _spin_lock ▒
>>>> + 48.05% futex_wait_setup ▒
>>>> + 47.79% futex_wake ▒
>>>> + 1.20% tcp_v4_rcv ▒
>>>> + 0.98% task_rq_lock ▒
>>>> + 0.64% double_lock_balance ▒
>>>> + 3.94% [ET_NET 0] libcrypto.so.1.0.1e [.] bn_mul_mont ▒
>>>> + 1.93% [ET_NET 0] libcrypto.so.1.0.1e [.] BN_usub ▒
>>>> + 1.80% [ET_NET 0] libcrypto.so.1.0.1e [.] 0x00000000000e5200 ▒
>>>> + 1.49% [ET_NET 0] libcrypto.so.1.0.1e [.] sha256_block_data_order ▒
>>>> + 0.97% [ET_NET 0] libcrypto.so.1.0.1e [.] gcm_ghash_clmul ▒
>>>> + 0.85% [ET_NET 0] libpthread-2.12.so [.] pthread_mutex_lock ▒
>>>> + 0.84% [ET_NET 0] libcrypto.so.1.0.1e [.] aesni_ctr32_encrypt_blocks ▒
>>>> + 0.74% [ET_NET 0] libc-2.12.so [.] malloc ▒
>>>> + 0.72% [ET_NET 0] libc-2.12.so [.] memcpy ▒
>>>> + 0.57% [ET_NET 0] libcrypto.so.1.0.1e [.] BN_mod_mul_montgomery ▒
>>>> + 0.51% [ET_NET 0] libpthread-2.12.so [.] pthread_mutex_unlock
>>>>
>>>> pstack of the process (only a couple of the interesting threads):
>>>> Thread 1 (Thread 0x7f1fba151800 (LWP 1106)):
>>>> #0 0x00007f1fbaaeb264 in __lll_lock_wait () from /lib64/libpthread.so.0
>>>> #1 0x00007f1fbaae6508 in _L_lock_854 () from /lib64/libpthread.so.0
>>>> #2 0x00007f1fbaae63d7 in pthread_mutex_lock () from /lib64/libpthread.so.0
>>>> #3 0x000000000072822f in SSL_locking_callback(int, int, char const*, int)
>>>> ()
>>>> #4 0x00000031d2ae7f03 in ?? () from /usr/lib64/libcrypto.so.10
>>>> #5 0x00000031d2ae7d8c in ?? () from /usr/lib64/libcrypto.so.10
>>>> #6 0x00000031d2ae80ab in ERR_get_state () from /usr/lib64/libcrypto.so.10
>>>> #7 0x00000031d2ae8557 in ?? () from /usr/lib64/libcrypto.so.10
>>>> #8 0x00000031d2e424a9 in SSL_get_error () from /usr/lib64/libssl.so.10
>>>> #9 0x00000000007249ef in SSLNetVConnection::load_buffer_and_write(long,
>>>> long&, long&, MIOBufferAccessor&, int&) ()
>>>> #10 0x00000000007389df in write_to_net_io(NetHandler*,
>>>> UnixNetVConnection*, EThread*) ()
>>>> #11 0x0000000000738523 in write_to_net(NetHandler*, UnixNetVConnection*,
>>>> EThread*) ()
>>>> #12 0x0000000000731922 in NetHandler::mainNetEvent(int, Event*) ()
>>>> #13 0x00000000004f6d48 in Continuation::handleEvent(int, void*) ()
>>>> #14 0x000000000075877a in EThread::process_event(Event*, int) ()
>>>> #15 0x0000000000758c84 in EThread::ex
>>>>
>>>> Thread 56 (Thread 0x7f1fb0ecd700 (LWP 1172)):
>>>> #0 0x00007f1fbaae77d9 in pthread_mutex_unlock () from
>>>> /lib64/libpthread.so.0
>>>> #1 0x0000000000728265 in SSL_locking_callback(int, int, char const*, int)
>>>> ()
>>>> #2 0x00000031d2b57402 in ?? () from /usr/lib64/libcrypto.so.10
>>>> #3 0x00000031d2b574bd in FIPS_selftest_failed () from
>>>> /usr/lib64/libcrypto.so.10
>>>> #4 0x00000031d2ae9f1c in EVP_DigestInit_ex () from
>>>> /usr/lib64/libcrypto.so.10
>>>> #5 0x00000031d2a7977e in HMAC_Init_ex () from /usr/lib64/libcrypto.so.10
>>>> #6 0x00000031d2a79c29 in ?? () from /usr/lib64/libcrypto.so.10
>>>> #7 0x00000031d2af7a42 in EVP_PKEY_CTX_ctrl () from
>>>> /usr/lib64/libcrypto.so.10
>>>> #8 0x00000031d2ae9ffb in EVP_DigestInit_ex () from
>>>> /usr/lib64/libcrypto.so.10
>>>> #9 0x00000031d2af952a in ?? () from /usr/lib64/libcrypto.so.10
>>>> #10 0x00000031d2e34cf2 in tls1_PRF () from /usr/lib64/libssl.so.10
>>>> #11 0x00000031d2e35796 in tls1_final_finish_mac () from
>>>> /usr/lib64/libssl.so.10
>>>> #12 0x00000031d2e2db2e in ssl3_get_message () from /usr/lib64/libssl.so.10
>>>> #13 0x00000031d2e1dc3c in ssl3_get_cert_verify () from
>>>> /usr/lib64/libssl.so.10
>>>> #14 0x00000031d2e220d6 in ssl3_accept () from /usr/lib64/libssl.so.10
>>>> #15 0x0000000000725287 in SSLNetVConnection::sslServerHandShakeEvent(int&)
>>>> ()
>>>> #16 0x00000000007251b3 in SSLNetVConnection::sslStartHandShake(int, int&)
>>>> ()
>>>> #17 0x0000000000723df3 in SSLNetVConnection::net_read_io(NetHandler*,
>>>> EThread*) ()
>>>> #18 0x0000000000731852 in NetHandler::mainNetEvent(int, Event*) ()
>>>> #19 0x00000000004f6d48 in Continuation::handleEvent(int, void*) ()
>>>> #20 0x000000000075877a in EThread::process_event(Event*, int) ()
>>>> #21 0x0000000000758c84 in EThread::execute() ()
>>>> #22 0x0000000000757cf8 in spawn_thread_internal(void*) ()
>>>> #23 0x00007f1fbaae49d1 in start_thread () from /lib64/libpthread.so.0
>>>> #24 0x00000030ff0e88fd in clone () from /lib64/libc.so.6
>>>>
>>>> -Bryan
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
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>>
>>
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