Re: git: 32a2fed6e71f - stable/13 - openssl: Fix detection of ARMv7 and ARM64 CPU features
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Date: Thu, 25 Nov 2021 17:59:18 UTC
On 11/25/2021 12:16 PM, Helge Oldach wrote: > Allan Jude wrote on Thu, 25 Nov 2021 17:54:06 +0100 (CET): >> On 11/25/2021 10:31 AM, Helge Oldach wrote: >>> Allan Jude wrote on Thu, 25 Nov 2021 16:09:25 +0100 (CET): >>>> On 11/25/2021 2:38 AM, Helge Oldach wrote: >>>>> hmo@p48 ~ $ for f in 0 1 2 3 8 16 32 64 128 ; do echo -n $f:; env OPENSSL_armcap=$f openssl speed -evp aes-256-gcm 2>&1 | tail -1 | cut -wf7; done >>>>> 0:42295.15k >>>>> 1:23891.19k >>>>> 2:42208.57k >>>>> 3:23970.56k >>>>> 8:42354.98k >>>>> 16:42199.06k >>>>> 32:size >>>>> Illegal instruction (core dumped) >>>>> 64:42322.42k >>>>> 128:42275.00k >>>>> hmo@p48 ~ $ >>>>> >>>>> So I guess HWCAP_FP is the culprit? Maybe related to hard/soft floating >>>>> point math which indeed is kind of special on the Pi? >>>> >>>> So yeah, the issue seems to be that floating point on the RPi4 is slower >>>> than not, but now openssl (properly) detects that the CPU advertises >>>> support for it. >>>> >>>> As seen elsewhere in the thread, most other ARM platforms get a very >>>> significant speed boost. >>> >>> So can we disable FP within OpenSSL for the RPi by default? This commit >>> basically introduced a regression for this platform and I think that >>> should be fixed. >>> >>> Or it the root cause a suboptimal FP implementation that is not adequate >>> for the RPi? >>> >>> Kind regards >>> Helge >>> >> >> The root cause is that the RPi4 advertises support for FP, but its FP is >> slow. >> >> I don't know that there is an easy way to detect the RPi4 specifically. >> You might be able to just disable the FP bit by setting >> OPENSSL_armcap=~1 globally, or maybe via openssl.conf? > > Sure can do that locally - but again: This commit is basically a > regression which IMHO should be fixed in a way not requiring users to > tweak things? > > Kind regards > Helge > It is only a regression to RPi4's, but a massive improvement to every other bit of ARM hardware that has been tested. The error that made OpenSSL disable FP before, was an error (it was calling AT_CANARY instead of AT_HWCAP). So, your issue with openssl being slow on the RPi4 will need to be taken up with OpenSSL. -- Allan Jude