From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50147) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cnQZb-0004s9-Dx for qemu-devel@nongnu.org; Mon, 13 Mar 2017 10:03:44 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cnQZX-0003fw-Dj for qemu-devel@nongnu.org; Mon, 13 Mar 2017 10:03:43 -0400 Received: from mout.kundenserver.de ([212.227.17.13]:55499) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1cnQZX-0003fC-3E for qemu-devel@nongnu.org; Mon, 13 Mar 2017 10:03:39 -0400 References: <20170224112109.3147-1-alex.bennee@linaro.org> <20170224112109.3147-12-alex.bennee@linaro.org> <87y3wr8zs2.fsf@linaro.org> From: Laurent Vivier Message-ID: Date: Mon, 13 Mar 2017 15:03:17 +0100 MIME-Version: 1.0 In-Reply-To: <87y3wr8zs2.fsf@linaro.org> 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: =?UTF-8?Q?Alex_Benn=c3=a9e?= Cc: peter.maydell@linaro.org, Peter Crosthwaite , qemu-devel@nongnu.org, Paolo Bonzini , KONRAD Frederic , Richard Henderson 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) ** Laurent