From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:59202) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1coZEl-00031I-RU for qemu-devel@nongnu.org; Thu, 16 Mar 2017 13:30:57 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1coZEi-0003I4-AB for qemu-devel@nongnu.org; Thu, 16 Mar 2017 13:30:55 -0400 Received: from mail-wm0-x230.google.com ([2a00:1450:400c:c09::230]:36924) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1coZEi-0003Hr-2M for qemu-devel@nongnu.org; Thu, 16 Mar 2017 13:30:52 -0400 Received: by mail-wm0-x230.google.com with SMTP id n11so53912334wma.0 for ; Thu, 16 Mar 2017 10:30:51 -0700 (PDT) References: <20170224112109.3147-1-alex.bennee@linaro.org> <20170224112109.3147-12-alex.bennee@linaro.org> <87y3wr8zs2.fsf@linaro.org> From: Alex =?utf-8?Q?Benn=C3=A9e?= In-reply-to: Date: Thu, 16 Mar 2017 17:31:10 +0000 Message-ID: <87wpbpnn6p.fsf@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Subject: Re: [Qemu-devel] [PULL 11/24] tcg: enable thread-per-vCPU List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Laurent Vivier Cc: peter.maydell@linaro.org, Peter Crosthwaite , qemu-devel@nongnu.org, Paolo Bonzini , KONRAD Frederic , Richard Henderson Laurent Vivier writes: > Le 27/02/2017 à 15:38, Alex Bennée a écrit : >> >> Laurent Vivier writes: >> >>> Le 24/02/2017 à 12:20, Alex Bennée a écrit : >>>> There are a couple of changes that occur at the same time here: >>>> >>>> - introduce a single vCPU qemu_tcg_cpu_thread_fn >>>> >>>> One of these is spawned per vCPU with its own Thread and Condition >>>> variables. qemu_tcg_rr_cpu_thread_fn is the new name for the old >>>> single threaded function. >>>> >>>> - the TLS current_cpu variable is now live for the lifetime of MTTCG >>>> vCPU threads. This is for future work where async jobs need to know >>>> the vCPU context they are operating in. >>>> >>>> The user to switch on multi-thread behaviour and spawn a thread >>>> per-vCPU. For a simple test kvm-unit-test like: >>>> >>>> ./arm/run ./arm/locking-test.flat -smp 4 -accel tcg,thread=multi >>>> >>>> Will now use 4 vCPU threads and have an expected FAIL (instead of the >>>> unexpected PASS) as the default mode of the test has no protection when >>>> incrementing a shared variable. >>>> >>>> We enable the parallel_cpus flag to ensure we generate correct barrier >>>> and atomic code if supported by the front and backends. This doesn't >>>> automatically enable MTTCG until default_mttcg_enabled() is updated to >>>> check the configuration is supported. >>> >>> This commit breaks linux-user mode: >>> >>> debian-8 with qemu-ppc on x86_64 with ltp-full-20170116 >>> >>> cd /opt/ltp >>> ./runltp -p -l "qemu-$(date +%FT%T).log" -f /opt/ltp/runtest/syscalls -s >>> setgroups03 >>> >>> setgroups03 1 TPASS : setgroups(65537) fails, Size is > >>> sysconf(_SC_NGROUPS_MAX), errno=22 >>> qemu-ppc: /home/laurent/Projects/qemu/include/qemu/rcu.h:89: >>> rcu_read_unlock: Assertion `p_rcu_reader->depth != 0' failed. >>> qemu-ppc: /home/laurent/Projects/qemu/include/qemu/rcu.h:89: >>> rcu_read_unlock: Assertion `p_rcu_reader->depth != 0' failed. >>> qemu-ppc: /home/laurent/Projects/qemu/include/qemu/rcu.h:89: >>> rcu_read_unlock: Assertion `p_rcu_reader->depth != 0' failed. >>> ... >> >> Interesting. I can only think the current_cpu change has broken it >> because most of the changes in this commit affect softmmu targets only >> (linux-user has its own run loop). >> >> Thanks for the report - I'll look into it. > > After: > > 95b0eca Merge remote-tracking branch > 'remotes/stsquad/tags/pull-mttcg-fixups-090317-1' into staging > > [Tested with my HEAD on: > b1616fe Merge remote-tracking branch > 'remotes/famz/tags/docker-pull-request' into staging] > > I have now: > > <<>> > tag=setgroups03 stime=1489413401 > cmdline="setgroups03" > contacts="" > analysis=exit > <<>> > ** > ERROR:/home/laurent/Projects/qemu/cpu-exec.c:656:cpu_exec: assertion > failed: (cpu == current_cpu) > ** Sorry about the delay. After lengthy fighting to get LTP on PowerPC built I got this behaviour: 17:26 alex@zen taken:41, git:mttcg/more-fixes-for-rc1, [/home/alex/lsrc/qemu/qemu.git]> sudo ./ppc-linux-user/qemu-ppc ./ppc-linux-user/setgroups03 setgroups03 1 TPASS : setgroups(65537) fails, Size is > sysconf(_SC_NGROUPS_MAX), errno=22 setgroups03 2 TBROK : tst_sig.c:233: unexpected signal SIGSEGV(11) received (pid = 22137). setgroups03 3 TBROK : tst_sig.c:233: Remaining cases broken I'm afraid I can't compare the result to real hardware so maybe my LTP build is broken. But the main thing is I can't seem to reproduce it here. Could you ping me your LTP binary so I can have a look? The other thing to note is the assert you now see firing is a guard for buggy compilers. What version are you building with and can you try any other versions? -- Alex Bennée