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Message-ID: <20140515094012.GA2435@openwall.com>
Date: Thu, 15 May 2014 13:40:13 +0400
From: Solar Designer <solar@...nwall.com>
To: john-dev@...ts.openwall.com
Subject: Re: c3 format broken w/ OMP on Solaris 11
magnum,
On Thu, May 15, 2014 at 12:17:47AM +0200, magnum wrote:
> I see a problem on Sparc Solaris 11 w/ gcc 4.5.2 building the crypt(3)
> format with OpenMP. I was testing Jumbo but this is a core problem.
>
> The problem is this pragma:
> #pragma omp parallel for default(none) private(index) shared(warned,
> count, crypt_out, saved_key, saved_salt, stderr)
>
> Compiler dies unless I change it do either
> #pragma omp parallel for default(none) private(index) shared(warned,
> count, crypt_out, saved_key, saved_salt, __iob)
>
> ...or just (That block is '#if __sun' and I'm not 100% sure __iob will
> work on just *any* __sun?)
> #pragma omp parallel for
Right. This was reported to me before, and I recorded it as:
"1.8.0's c3_fmt.c fails to build with OpenMP on Solaris (needs __iob)"
I should fix it for 1.8.1.
> However, after fixing that I still have some problems. First, it does
> not actually seem to use OMP although it prints it does:
>
> Warning: OpenMP is disabled; a non-OpenMP build may be faster
> Benchmarking: crypt, generic crypt(3) DES [?/32]... DONE
> Many salts: 864 c/s real, 872 c/s virtual
> Only one salt: 872 c/s real, 872 c/s virtual
>
> Will run 8 OpenMP threads
> Benchmarking: crypt, generic crypt(3) DES [?/32]... (8xOMP) DONE
> Many salts: 855 c/s real, 838 c/s virtual
> Only one salt: 864 c/s real, 842 c/s virtual
That's because Solaris' descrypt code has a mutex in it (I think). You
need to test on a hash type that we actually care to use this generic
code with - e.g., sha512crypt and SunMD5 show decent OpenMP scaling.
(Of course, jumbo's code for these is faster yet.)
> Second, only seen in --test=0 (all formats) runs so far, it sometimes
> just hangs after printing this:
> Testing: crypt, generic crypt(3) DES [?/32]... (8xOMP)
>
> It hangs forever with 0% CPU load. I don't actually care about this
> (we're just doing Jumbo BE tests :) but now you have been notified.
Oh, this is a new thing. Sounds like they might have a deadlock in
(des)crypt code - maybe they try to acquire more than one lock? You
could want to investigate this and report a Solaris bug.
> BTW the man page on that machine does state that crypt() is MT safe.
Yes, Solaris' crypt() is documented as MT-safe, and we rely on that.
Alexander
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