From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id 45D8A3850857; Tue, 6 Sep 2022 13:33:05 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 45D8A3850857 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1662471185; bh=/1pBII/Xc028k/V1Rjg2K3lrLyl9ZO7Gt2XmSIa4bDU=; h=From:To:Subject:Date:In-Reply-To:References:From; b=W0XsvFsIZyiZsde0RKRiIU0hTtkM1nh7FxWT93SgZC0XoR97J1riHl4YYPqNgUor4 YJJdtW/EIYs1bbm7Xpa0LG4Kca85nllNjikPCMOV/lvN4+X+7kZj613QL2UAwNx1YM 7lP0xvNH2hPtCMyFqZgV4e6y93QPqaSZWlKLkVJQ= From: "vries at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug target/99555] [OpenMP/nvptx] Execution-time hang for simple nested OpenMP 'target'/'parallel'/'task' constructs Date: Tue, 06 Sep 2022 13:32:59 +0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: target X-Bugzilla-Version: 11.0 X-Bugzilla-Keywords: openmp, wrong-code X-Bugzilla-Severity: normal X-Bugzilla-Who: vries at gcc dot gnu.org X-Bugzilla-Status: RESOLVED X-Bugzilla-Resolution: FIXED X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: 12.0 X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 List-Id: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D99555 --- Comment #17 from Tom de Vries --- (In reply to Thomas Schwinge from comment #14) > > That's with a Nvidia Tesla K20c GPU, Driver Version: 346.46. > > As that version is "a bit old", I shall first update this, before we sp= end > > any further time on analyzing this. >=20 > Cross-checking on another system with Nvidia Tesla K20c GPU but more rece= nt > Driver Version I'm not seeing such an issue. >=20 > On the "old" system, gradually upgrading Driver Version: 346.46 to 352.99, > 361.93.02, 375.88 (always the latest (?) version of the respective series= ), > these all did not resolve the problem. >=20 > Only starting with 384.59 (that is, early version of the 384.X series), t= hat > then did resolve the issue. That's still using the GCC/nvptx '-mptx=3D3.= 1' > multilib. >=20 > (We couldn't with earlier series, but given this is 384.X, we may now also > cross-check with the default multilib, and that also was fine.) >=20 > Now, I don't know if at all we would like to spend any more effort on this > issue, given that it only appears with rather old pre-384.X versions -- b= ut > on the other hand, the GCC/nvptx '-mptx=3D3.1' multilib is meant to keep = these > supported? (... which is why I'm running such testing; and certainly the > timeouts are annoying there.) >=20 > It might be another issue with pre-384.X versions of the Nvidia PTX JIT, = or > is there the slight possibility that GCC is generating/libgomp contains s= ome > "weird" code that post-384.X version happen to "fix up" -- probably the > former rather than the latter? (Or, the chance of GPU hardware/firmware = or > some other system weirdness -- unlikely, otherwise behaves totally fine?) >=20 > I don't know where to find complete Nvidia Driver/JIT release notes, where > the 375.X -> 384.X notes might provide an idea of what got fixed, and we > might then add another 'WORKAROUND_PTXJIT_BUG' for that -- maybe simple, > maybe not. >=20 > Any thoughts, Tom? I care about old cards, not about old drivers. The oldest card we support = is an sm_30, and last driver series that supports that one is 470.x (and AFAIU= , is therefore supported by nvidia for that arch). There's the legacy series, 390.x, which is the last to support fermi, but we don't support any fermi cards or earlier. I did do some testing with this = one for later cards, but reported issues are acknowledged but not fixed by nvid= ia, so ... this is already out of scope for me. So yeah, IWBN to come up with workarounds for various older drivers, but I'm not investing time in that. Is there a problem for you to move to 470.x or later (515.x) ? Is there a card for which that causes problems ?=