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[106.167.171.201]) by smtp.gmail.com with ESMTPSA id q185sm4525886pfb.82.2020.05.26.03.50.49 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 26 May 2020 03:50:52 -0700 (PDT) Subject: Re: Some -serious- BPF-related litmus tests To: Andrii Nakryiko , luc.maranget@inria.fr Cc: Andrii Nakryiko , "Paul E . McKenney" , Alan Stern , Peter Zijlstra , parri.andrea@gmail.com, will@kernel.org, boqun.feng@gmail.com, npiggin@gmail.com, dhowells@redhat.com, j.alglave@ucl.ac.uk, dlustig@nvidia.com, Joel Fernandes , open list , linux-arch@vger.kernel.org, Akira Yokosawa References: <20200522003850.GA32698@paulmck-ThinkPad-P72> <20200522094407.GK325280@hirez.programming.kicks-ass.net> <20200522143201.GB32434@rowland.harvard.edu> <20200522174352.GJ2869@paulmck-ThinkPad-P72> <006e2bc6-7516-1584-3d8c-e253211c157e@fb.com> <69ed3604-4275-d73e-a5d6-2b70dd877104@gmail.com> From: Akira Yokosawa Message-ID: Date: Tue, 26 May 2020 19:50:47 +0900 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 25 May 2020 16:31:05 -0700, Andrii Nakryiko wrote: > On Mon, May 25, 2020 at 3:01 PM Akira Yokosawa wrote= : >> [...] >> Yes, that should work. >=20 > Ok, assigning to zero didn't work (it still complained about > uninitialized read), but using a separate int *lenFail to assign to > rLenPtr worked. Curiously, if I used rLenPtr =3D len1; in error case, i= t > actually takes a bit more time to verify. >=20 > So I've converted everything else as you suggested. I compiled latest > herd7 and it doesn't produce any warnings. But it's also extremely > slow, compared to the herd7 that I get by default. Validating simple > 1p1c cases takes about 2.5x times longer (0.03s vs 0.07), but trying > to validate 2p1c case, which normally validates in 42s (unbounded) and > 110s (bounded), it took more than 20 minutes and hasn't finished, > before I gave up. So I don't know what's going on there... herdtools7 has recently been heavily restructured. On the performance regression, I must defer to Luc. Luc, do you have any idea? >=20 > As for klitmus7, I managed to generate everything without warnings, > but couldn't make it build completely due to: >=20 > $ make > make -C /lib/modules/5.6.13-01802-g938d64da97c6/build/ So you are on Linux 5.6.x which requires cutting-edge klitmus7. > M=3D/home/andriin/local/linux-trees/tools/memory-model/mymodules module= s > make[1]: Entering directory `/data/users/andriin/linux-build/fb-config'= > make[2]: Entering directory `/data/users/andriin/linux-build/default-x8= 6_64' > CC [M] /home/andriin/local/linux-trees/tools/memory-model/mymodules/= litmus000.o > /home/andriin/local/linux-trees/tools/memory-model/mymodules/litmus000.= c: > In function =E2=80=98zyva=E2=80=99: > /home/andriin/local/linux-trees/tools/memory-model/mymodules/litmus000.= c:507:12: > warning: ISO C90 forbids variable length array =E2=80=98th=E2=80=99 [-W= vla] > struct task_struct *th[nth]; > ^~~~~~~~~~~ > /home/andriin/local/linux-trees/tools/memory-model/mymodules/litmus000.= c: > In function =E2=80=98litmus_init=E2=80=99: > /home/andriin/local/linux-trees/tools/memory-model/mymodules/litmus000.= c:605:67: > error: passing argument 4 of =E2=80=98proc_create=E2=80=99 from incompa= tible pointer > type [-Werror=3Dincompatible-pointer-types] > struct proc_dir_entry *litmus_pde =3D > proc_create("litmus",0,NULL,&litmus_proc_fops); >=20 > ^~~~~~~~~~~~~~~~~ > In file included from > /home/andriin/local/linux-trees/tools/memory-model/mymodules/litmus000.= c:15: > /data/users/andriin/linux-fb/include/linux/proc_fs.h:64:24: note: > expected =E2=80=98const struct proc_ops *=E2=80=99 but argument is of t= ype =E2=80=98const > struct file_operations *=E2=80=99 > struct proc_dir_entry *proc_create(const char *name, umode_t mode, > struct proc_dir_entry *parent, const struct proc_ops *proc_ops); > ^~~~~~~~~~~ > cc1: some warnings being treated as errors > make[3]: *** [/home/andriin/local/linux-trees/tools/memory-model/mymodu= les/litmus000.o] > Error 1 > make[2]: *** [/home/andriin/local/linux-trees/tools/memory-model/mymodu= les] > Error 2 > make[2]: Leaving directory `/data/users/andriin/linux-build/default-x86= _64' > make[1]: *** [sub-make] Error 2 > make[1]: Leaving directory `/data/users/andriin/linux-build/fb-config' > make: *** [all] Error 2 >=20 These errors suggest the klitmus7 you used is version 7.52 or some such. You said you have built herd7 from the source. Have you also built klitm= us7? The up-to-date klitmus7 should generate code compatible with Linux 5.6.x.= Could you try with the latest one? Thanks, Akira >=20 > But at least it doesn't complain about atomic_t anymore. So anyways, > I'm going to post updated litmus tests separately from BPF ringbuf > patches, because Documentation/litmus-tests is not yet present in > bpf-next. >=20 >> >> You can find a basic introduction of klitmus7 in tools/memory-model/RE= ADME. >> >> Thanks, Akira >> >>> >>>> >>>> Please note that if you are on Linux 5.6 (or later), you need an up-= to-date >>>> klitmus7 due to a change in kernel API. >>>> >>>> Any question is welcome! >>>> >>>> Thanks, Akira >>>> >=20 > [...] >=20