From: Robert Foley <robert.foley@linaro.org> To: "Emilio G. Cota" <cota@braap.org> Cc: "Richard Henderson" <richard.henderson@linaro.org>, "Alex Bennée" <alex.bennee@linaro.org>, "QEMU Developers" <qemu-devel@nongnu.org>, "Peter Puhov" <peter.puhov@linaro.org> Subject: Re: [PATCH v8 74/74] cputlb: queue async flush jobs without the BQL Date: Wed, 20 May 2020 11:01:20 -0400 Message-ID: <CAEyhzFuraifsPTBrM2g+KQVWvD09Q3fwdh=fCo+a9YOTRBAMeg@mail.gmail.com> (raw) In-Reply-To: <20200520044613.GA359481@sff> On Wed, 20 May 2020 at 00:46, Emilio G. Cota <cota@braap.org> wrote: > > On Mon, May 18, 2020 at 09:46:36 -0400, Robert Foley wrote: > > Thanks for doing these tests. I know from experience that benchmarking > is hard and incredibly time consuming, so please do not be discouraged by > my comments below. > Hi, Thanks for all the comments, and for including the script! These are all very helpful. We will work to replicate these results using a PPC VM, and will re-post them here. Thanks & Regards, -Rob > A couple of points: > > 1. I am not familiar with aarch64 KVM but I'd expect it to scale almost > like the native run. Are you assigning enough RAM to the guest? Also, > it can help to run the kernel build in a ramfs in the guest. > 2. The build itself does not seem to impose a scaling limit, since > it scales very well when run natively (per-thread I presume aarch64 TCG is > still slower than native, even if TCG is run on a faster x86 machine). > The limit here is probably aarch64 TCG. In particular, last time I > checked aarch64 TCG has room for improvement scalability-wise handling > interrupts and some TLB operations; this is likely to explain why we > see no benefit with per-CPU locks, i.e. the bottleneck is elsewhere. > This can be confirmed with the sync profiler. > > IIRC I originally used ppc64 for this test because ppc64 TCG does not > have any other big bottlenecks scalability-wise. I just checked but > unfortunately I can't find the ppc64 image I used :( What I can offer > is the script I used to run these benchmarks; see the appended. > > Thanks, > Emilio > > --- > #!/bin/bash > > set -eu > > # path to host files > MYHOME=/local/home/cota/src > > # guest image > QEMU_INST_PATH=$MYHOME/qemu-inst > IMG=$MYHOME/qemu/img/ppc64/ubuntu.qcow2 > > ARCH=ppc64 > COMMON_ARGS="-M pseries -nodefaults \ > -hda $IMG -nographic -serial stdio \ > -net nic -net user,hostfwd=tcp::2222-:22 \ > -m 48G" > > # path to this script's directory, where .txt output will be copied > # from the guest. > QELT=$MYHOME/qelt > HOST_PATH=$QELT/fig/kcomp > > # The guest must be able to SSH to the HOST without entering a password. > # The way I set this up is to have a passwordless SSH key in the guest's > # root user, and then copy that key's public key to the host. > # I used the root user because the guest runs on bootup (as root) a > # script that scp's run-guest.sh (see below) from the host, then executes it. > # This is done via a tiny script in the guest invoked from systemd once > # boot-up has completed. > HOST=foo@bar.edu > > # This is a script in the host to use an appropriate cpumask to > # use cores in the same socket if possible. > # See https://github.com/cota/cputopology-perl > CPUTOPO=$MYHOME/cputopology-perl > > # For each run we create this file that then the guest will SCP > # and execute. It is a quick and dirty way of passing arguments to the guest. > create_file () { > TAG=$1 > CORES=$2 > NAME=$ARCH.$TAG-$CORES.txt > > echo '#!/bin/bash' > run-guest.sh > echo 'cp -r /home/cota/linux-4.18-rc7 /tmp2/linux' >> run-guest.sh > echo "cd /tmp2/linux" >> run-guest.sh > echo "{ time make -j $CORES vmlinux >/dev/null; } 2>>/home/cota/$NAME" >> run-guest.sh > # Output with execution time is then scp'ed to the host. > echo "ssh $HOST 'cat >> $HOST_PATH/$NAME' < /home/cota/$NAME" >> run-guest.sh > echo "poweroff" >> run-guest.sh > } > > # Change here THREADS and also the TAGS that point to different QEMU installations. > for THREADS in 64 32 16; do > for TAG in cpu-exclusive-work cputlb-no-bql per-cpu-lock cpu-has-work baseline; do > QEMU=$QEMU_INST_PATH/$TAG/bin/qemu-system-$ARCH > CPUMASK=$($CPUTOPO/list.pl --policy=compact-smt $THREADS) > > create_file $TAG $THREADS > time taskset -c $CPUMASK $QEMU $COMMON_ARGS -smp $THREADS > done > done
next prev parent reply index Thread overview: 100+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-03-26 19:30 [PATCH v8 00/74] per-CPU locks Robert Foley 2020-03-26 19:30 ` [PATCH v8 01/74] cpu: convert queued work to a QSIMPLEQ Robert Foley 2020-03-26 19:30 ` [PATCH v8 02/74] cpu: rename cpu->work_mutex to cpu->lock Robert Foley 2020-05-11 14:48 ` Alex Bennée 2020-05-11 16:33 ` Robert Foley 2020-03-26 19:30 ` [PATCH v8 03/74] cpu: introduce cpu_mutex_lock/unlock Robert Foley 2020-05-11 10:24 ` Alex Bennée 2020-05-11 16:09 ` Robert Foley 2020-03-26 19:30 ` [PATCH v8 04/74] cpu: make qemu_work_cond per-cpu Robert Foley 2020-03-26 19:30 ` [PATCH v8 05/74] cpu: move run_on_cpu to cpus-common Robert Foley 2020-03-26 19:30 ` [PATCH v8 06/74] cpu: introduce process_queued_cpu_work_locked Robert Foley 2020-03-26 19:30 ` [PATCH v8 07/74] cpu: make per-CPU locks an alias of the BQL in TCG rr mode Robert Foley 2020-03-26 19:30 ` [PATCH v8 08/74] tcg-runtime: define helper_cpu_halted_set Robert Foley 2020-03-26 19:30 ` [PATCH v8 09/74] ppc: convert to helper_cpu_halted_set Robert Foley 2020-03-26 19:30 ` [PATCH v8 10/74] cris: " Robert Foley 2020-03-26 19:30 ` [PATCH v8 11/74] hppa: " Robert Foley 2020-03-26 19:30 ` [PATCH v8 12/74] m68k: " Robert Foley 2020-03-26 19:30 ` [PATCH v8 13/74] alpha: " Robert Foley 2020-03-26 19:30 ` [PATCH v8 14/74] microblaze: " Robert Foley 2020-03-26 19:30 ` [PATCH v8 15/74] cpu: define cpu_halted helpers Robert Foley 2020-03-26 19:30 ` [PATCH v8 16/74] tcg-runtime: convert to cpu_halted_set Robert Foley 2020-03-26 19:30 ` [PATCH v8 17/74] hw/semihosting: " Robert Foley 2020-05-11 10:25 ` Alex Bennée 2020-03-26 19:31 ` [PATCH v8 18/74] arm: convert to cpu_halted Robert Foley 2020-03-26 19:31 ` [PATCH v8 19/74] ppc: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 20/74] sh4: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 21/74] i386: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 22/74] lm32: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 23/74] m68k: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 24/74] mips: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 25/74] riscv: " Robert Foley 2020-05-11 10:40 ` Alex Bennée 2020-05-11 16:13 ` Robert Foley 2020-03-26 19:31 ` [PATCH v8 26/74] s390x: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 27/74] sparc: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 28/74] xtensa: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 29/74] gdbstub: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 30/74] openrisc: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 31/74] cpu-exec: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 32/74] cpu: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 33/74] cpu: define cpu_interrupt_request helpers Robert Foley 2020-03-26 19:31 ` [PATCH v8 34/74] ppc: use cpu_reset_interrupt Robert Foley 2020-03-26 19:31 ` [PATCH v8 35/74] exec: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 36/74] i386: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 37/74] s390x: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 38/74] openrisc: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 39/74] arm: convert to cpu_interrupt_request Robert Foley 2020-03-26 19:31 ` [PATCH v8 40/74] i386: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 41/74] i386/kvm: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 42/74] i386/hax-all: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 43/74] i386/whpx-all: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 44/74] i386/hvf: convert to cpu_request_interrupt Robert Foley 2020-03-26 19:31 ` [PATCH v8 45/74] ppc: convert to cpu_interrupt_request Robert Foley 2020-03-26 19:31 ` [PATCH v8 46/74] sh4: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 47/74] cris: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 48/74] hppa: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 49/74] lm32: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 50/74] m68k: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 51/74] mips: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 52/74] nios: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 53/74] s390x: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 54/74] alpha: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 55/74] moxie: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 56/74] sparc: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 57/74] openrisc: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 58/74] unicore32: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 59/74] microblaze: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 60/74] accel/tcg: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 61/74] cpu: convert to interrupt_request Robert Foley 2020-03-26 19:31 ` [PATCH v8 62/74] cpu: call .cpu_has_work with the CPU lock held Robert Foley 2020-03-26 19:31 ` [PATCH v8 63/74] cpu: introduce cpu_has_work_with_iothread_lock Robert Foley 2020-03-26 19:31 ` [PATCH v8 64/74] ppc: convert to cpu_has_work_with_iothread_lock Robert Foley 2020-03-26 19:31 ` [PATCH v8 65/74] mips: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 66/74] s390x: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 67/74] riscv: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 68/74] sparc: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 69/74] xtensa: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 70/74] cpu: rename all_cpu_threads_idle to qemu_tcg_rr_all_cpu_threads_idle Robert Foley 2020-03-26 19:31 ` [PATCH v8 71/74] cpu: protect CPU state with cpu->lock instead of the BQL Robert Foley 2020-03-26 19:31 ` [PATCH v8 72/74] cpus-common: release BQL earlier in run_on_cpu Robert Foley 2020-03-26 19:31 ` [PATCH v8 73/74] cpu: add async_run_on_cpu_no_bql Robert Foley 2020-03-26 19:31 ` [PATCH v8 74/74] cputlb: queue async flush jobs without the BQL Robert Foley 2020-05-12 16:27 ` Alex Bennée 2020-05-12 19:26 ` Robert Foley 2020-05-18 13:46 ` Robert Foley 2020-05-20 4:46 ` Emilio G. Cota 2020-05-20 15:01 ` Robert Foley [this message] 2020-05-21 14:17 ` Robert Foley 2020-05-12 18:38 ` Alex Bennée 2020-03-26 22:58 ` [PATCH v8 00/74] per-CPU locks Aleksandar Markovic 2020-03-27 9:39 ` Alex Bennée 2020-03-27 9:50 ` Aleksandar Markovic 2020-03-27 10:24 ` Aleksandar Markovic 2020-03-27 17:21 ` Robert Foley 2020-03-27 5:14 ` Emilio G. Cota 2020-03-27 10:59 ` Philippe Mathieu-Daudé 2020-03-30 8:57 ` Stefan Hajnoczi 2020-03-27 18:23 ` Alex Bennée 2020-03-27 18:30 ` Robert Foley 2020-05-12 16:29 ` Alex Bennée
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