crypto: recent large performance regressions

[mscdex]

• Version: master
• Platform: linux
• Subsystem: crypto

While working on a system that automatically and regularly runs benchmarks on master and compares the results between builds, I found some large crypto performance regressions between f368210 and 93c4c1a. Here are the crypto benchmarks that showed a greater than 10% regression (numeric values below are the % change with "***" confidence):

'aes-gcm-throughput': {
   'cipher="aes-128-gcm" len=1024 n=500': -45.12,
   'cipher="aes-128-gcm" len=4096 n=500': -29.89,
   'cipher="aes-128-gcm" len=16384 n=500': -13.18,
   'cipher="aes-192-gcm" len=1024 n=500': -44.51,
   'cipher="aes-192-gcm" len=4096 n=500': -30.73,
   'cipher="aes-192-gcm" len=16384 n=500': -10.44,
   'cipher="aes-256-gcm" len=1024 n=500': -44.13,
   'cipher="aes-256-gcm" len=4096 n=500': -27.38,
   'cipher="aes-256-gcm" len=16384 n=500': -11.74 },
'hash-stream-creation': {
   'algo="sha256" api="legacy" len=2 out="hex" type="asc" writes=500': -68.41,
   'algo="sha256" api="legacy" len=1024 out="hex" type="asc" writes=500': -60.25,
   'algo="sha256" api="legacy" len=2 out="binary" type="asc" writes=500': -68.58,
   'algo="sha256" api="legacy" len=1024 out="binary" type="asc" writes=500': -60.51,
   'algo="sha256" api="legacy" len=2 out="buffer" type="asc" writes=500': -64.06,
   'algo="sha256" api="legacy" len=1024 out="buffer" type="asc" writes=500': -57.33,
   'algo="sha256" api="legacy" len=2 out="hex" type="utf" writes=500': -69.56,
   'algo="sha256" api="legacy" len=1024 out="hex" type="utf" writes=500': -58.65,
   'algo="sha256" api="legacy" len=2 out="binary" type="utf" writes=500': -70.01,
   'algo="sha256" api="legacy" len=1024 out="binary" type="utf" writes=500': -58.88,
   'algo="sha256" api="legacy" len=2 out="buffer" type="utf" writes=500': -65.12,
   'algo="sha256" api="legacy" len=1024 out="buffer" type="utf" writes=500': -56.01,
   'algo="sha256" api="legacy" len=2 out="hex" type="buf" writes=500': -67.46,
   'algo="sha256" api="legacy" len=1024 out="hex" type="buf" writes=500': -58.93,
   'algo="sha256" api="legacy" len=2 out="binary" type="buf" writes=500': -67.74,
   'algo="sha256" api="legacy" len=1024 out="binary" type="buf" writes=500': -58.98,
   'algo="sha256" api="legacy" len=2 out="buffer" type="buf" writes=500': -62.85,
   'algo="sha256" api="legacy" len=1024 out="buffer" type="buf" writes=500': -55.95,
   'algo="md5" api="legacy" len=2 out="hex" type="asc" writes=500': -68.92,
   'algo="md5" api="legacy" len=1024 out="hex" type="asc" writes=500': -65.12,
   'algo="md5" api="legacy" len=102400 out="hex" type="asc" writes=500': -11.61,
   'algo="md5" api="legacy" len=2 out="binary" type="asc" writes=500': -69.65,
   'algo="md5" api="legacy" len=1024 out="binary" type="asc" writes=500': -65.85,
   'algo="md5" api="legacy" len=102400 out="binary" type="asc" writes=500': -11.46,
   'algo="md5" api="legacy" len=2 out="buffer" type="asc" writes=500': -64.73,
   'algo="md5" api="legacy" len=1024 out="buffer" type="asc" writes=500': -61.71,
   'algo="md5" api="legacy" len=102400 out="buffer" type="asc" writes=500': -11.4,
   'algo="md5" api="legacy" len=2 out="hex" type="utf" writes=500': -70.09,
   'algo="md5" api="legacy" len=1024 out="hex" type="utf" writes=500': -63.91,
   'algo="md5" api="legacy" len=2 out="binary" type="utf" writes=500': -70.61,
   'algo="md5" api="legacy" len=1024 out="binary" type="utf" writes=500': -63.95,
   'algo="md5" api="legacy" len=2 out="buffer" type="utf" writes=500': -65.73,
   'algo="md5" api="legacy" len=1024 out="buffer" type="utf" writes=500': -60.23,
   'algo="md5" api="legacy" len=2 out="hex" type="buf" writes=500': -67.93,
   'algo="md5" api="legacy" len=1024 out="hex" type="buf" writes=500': -63.9,
   'algo="md5" api="legacy" len=102400 out="hex" type="buf" writes=500': -11.59,
   'algo="md5" api="legacy" len=2 out="binary" type="buf" writes=500': -68.48,
   'algo="md5" api="legacy" len=1024 out="binary" type="buf" writes=500': -64.36,
   'algo="md5" api="legacy" len=102400 out="binary" type="buf" writes=500': -11.55,
   'algo="md5" api="legacy" len=2 out="buffer" type="buf" writes=500': -63.59,
   'algo="md5" api="legacy" len=1024 out="buffer" type="buf" writes=500': -60.13,
   'algo="md5" api="legacy" len=102400 out="buffer" type="buf" writes=500': -11.73 },
'hash-stream-throughput': {
   'algo="sha1" api="legacy" len=2 type="asc" writes=500': -35.71,
   'algo="sha1" api="legacy" len=1024 type="asc" writes=500': -24.66,
   'algo="sha1" api="legacy" len=2 type="utf" writes=500': -41.67,
   'algo="sha1" api="legacy" len=1024 type="utf" writes=500': -21.52,
   'algo="sha1" api="legacy" len=2 type="buf" writes=500': -33.78,
   'algo="sha1" api="legacy" len=1024 type="buf" writes=500': -22.71,
   'algo="sha256" api="legacy" len=2 type="asc" writes=500': -36.48,
   'algo="sha256" api="legacy" len=1024 type="asc" writes=500': -18.78,
   'algo="sha256" api="legacy" len=2 type="utf" writes=500': -41.03,
   'algo="sha256" api="legacy" len=1024 type="utf" writes=500': -16.56,
   'algo="sha256" api="legacy" len=2 type="buf" writes=500': -33.76,
   'algo="sha256" api="legacy" len=1024 type="buf" writes=500': -17.47,
   'algo="sha512" api="legacy" len=2 type="asc" writes=500': -36.95,
   'algo="sha512" api="legacy" len=1024 type="asc" writes=500': -20.98,
   'algo="sha512" api="legacy" len=2 type="utf" writes=500': -42.2,
   'algo="sha512" api="legacy" len=1024 type="utf" writes=500': -18.5,
   'algo="sha512" api="legacy" len=2 type="buf" writes=500': -34.29,
   'algo="sha512" api="legacy" len=1024 type="buf" writes=500': -19.05 },

The culprits seem to be at least e559842 and possibly also d016b9d.

/cc @ronag

[ronag]

e559842 could be a cause if crypto related code uses writable/readable.

d016b9d I'm very sceptical whether it could/should have any performance impact in a hot path.