Re: libc recently more aggressive about pthread locks in stable ?
On Thu, Nov 17, 2016, at 09:50, Adrian Bunk wrote:
> But we do already have > 1 year of widespread testing by users
> running unstable/testing on machines with TSX enabled.
>
> So for unstable/stretch this does not seem to be a huge problem.
>
> These are normal bugs that should be found and fixed if possible,
> just like passing a pointer in an int or many other kinds of bugs.
>
> Or do I miss anything here?
I am not sure we have that much user coverage, given the blacklisting we
did in glibc. Maybe a search for lock elision bug reports in relevant
Ubuntu releases would help... I think their glibc packages are close
enough to ours that they would have the same issues we do.
The current blacklist in Jessie's glibc is:
((model == 63 && stepping <= 2) || (model == 60 && stepping <= 3) ||
(model == 69 && stepping <= 1) || (model == 70 && stepping <= 1) ||
(model == 61 && stepping <= 4) || (model == 71 && stepping <= 1) ||
(model == 86 && stepping <= 2) ))
Which should be (ignoring ES/QS steppings, which were also blacklisted):
Haswell:
Signature: 0x306f2, main model: Haswell-E (Xeon E5v3, Core Extreme 4th
gen)
Signature: 0x306c3, main model: Haswell-DT (desktop Core 4th gen)
Signature: 0x40651, main model: Haswell low power (mobile Core 4th gen)
Signature: 0x40661, main model: Haswell "Crystal Well") (Core 4th gen
with eDRAM)
So, almost all of Haswell is blacklisted. The known exception is Xeon
E7v3 (signature 0x306f4), which was not blacklisted because apparently
either Intel TSX works well enough there, or it is never reported as
enabled in the first place.
Broadwell:
Signature: 0x306d4, main model: Broadwell (desktop and mobile Core 5th
gen)
Signature: 0x40671, main model: Broadwell "Brystal Well" (Core 5th gen
with eDRAM, also Xeon E3v4)
Signature: 0x50662, main model: Broadwell-DE (Xeon D-1500, stepping V1)
-- due to BDE42.
Note that newer steppings of Broadwell-DE are not blacklisted (0x50663:
stepping V2, 0x50664: stepping Y0 -- BDE85 fixed by up-to-date
microcode). Also, Broadwell-EN/EP/EX (Core Extreme 5th gen, Xeon E5v4
and E7v4) are not blacklisted, either.
--
Henrique de Moraes Holschuh <hmh@debian.org>
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