Bug 1281849
| Summary: | asan-instrumented qemu running order of magnitude slower than qemu without address sanitizer | ||
|---|---|---|---|
| Product: | Red Hat Enterprise Linux 8 | Reporter: | David Jaša <djasa> |
| Component: | gcc | Assignee: | Marek Polacek <mpolacek> |
| gcc sub component: | system-version | QA Contact: | qe-baseos-tools-bugs |
| Status: | CLOSED WONTFIX | Docs Contact: | |
| Severity: | unspecified | ||
| Priority: | unspecified | CC: | ahajkova, dodji, fweimer, jakub, law, mnewsome, mpetlan, mpolacek, ohudlick, sipoyare |
| Version: | 8.1 | Keywords: | Triaged |
| Target Milestone: | pre-dev-freeze | ||
| Target Release: | 8.1 | ||
| Hardware: | Unspecified | ||
| OS: | Unspecified | ||
| Whiteboard: | |||
| Fixed In Version: | Doc Type: | If docs needed, set a value | |
| Doc Text: | Story Points: | --- | |
| Clone Of: | Environment: | ||
| Last Closed: | 2020-10-06 16:12:35 UTC | Type: | Bug |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Embargoed: | |||
| Bug Depends On: | |||
| Bug Blocks: | 1413146 | ||
Example qemu command line for such a real VM (adopted from libvirt): ASAN_OPTIONS=symbolize=1:verbosity=10:fast_unwind_on_fatal=1:fast_unwind_on_malloc=1:abort_on_error=1 \ ASAN_SYMBOLIZER_PATH=/usr/bin/llvm-symbolizer LC_ALL=C G_SLICE=always-malloc \ USER=<YOUR_USER> LOGNAME=<YOUR_USER> QEMU_AUDIO_DRV=spice SPICE_DEBUG_LEVEL=4 \ perf record -a --call-graph fp -s -o tmp/qemu_with_asan.raw -- gdb \ rpmbuild/BUILDROOT/qemu-kvm-rhev-2.3.0-31.el7_2.1.sanitizer.x86_64-gcc/usr/libexec/qemu-kvm \ --ex "handle SIGPIPE nostop noprint pass" --ex "-name win7u -S -machine pc-i440fx-rhel7.0.0,accel=kvm,usb=off -cpu Nehalem -m 1536 -realtime mlock=off -smp 1,sockets=1,cores=1,threads=1 -uuid UUID -no-user-config -nodefaults -monitor stdio -rtc base=localtime,driftfix=slew -global kvm-pit.lost_tick_policy=discard -no-hpet -no-shutdown -global PIIX4_PM.disable_s3=1 -global PIIX4_PM.disable_s4=1 -boot strict=on -device virtio-scsi-pci,id=scsi0,bus=pci.0,addr=0x7 -device virtio-serial-pci,id=virtio-serial0,bus=pci.0,addr=0x6 -drive file=/PATH/TO/IMAGE,if=none,id=drive-scsi0-0-0-0,format=FORMAT,discard=unmap -device scsi-hd,bus=scsi0.0,channel=0,scsi-id=0,lun=0,drive=drive-scsi0-0-0-0,id=scsi0-0-0-0,bootindex=1 -netdev tap,ifname=TAP_DEVICE_NAME,script=no,id=hostnet0 -device virtio-net-pci,netdev=hostnet0,id=net0,mac=MAC_ADDRESS,bus=pci.0,addr=0x3 -chardev spicevmc,id=charchannel0,name=vdagent -device virtserialport,bus=virtio-serial0.0,nr=1,chardev=charchannel0,id=channel0,name=com.redhat.spice.0 -spice port=5800,addr=::,disable-ticketing,seamless-migration=on -vga qxl -global qxl-vga.ram_size=134217728 -global qxl-vga.vram_size=33554432 -global qxl-vga.vgamem_mb=32 -device qxl,id=video1,bus=pci.0,addr=0x9 -device qxl,id=video2,bus=pci.0,addr=0xa -device qxl,id=video3,bus=pci.0,addr=0xb -device intel-hda,id=sound0,bus=pci.0,addr=0x4 -device hda-duplex,id=sound0-codec0,bus=sound0.0,cad=0 -chardev spicevmc,id=charredir0,name=usbredir -msg timestamp=on" to pre-create tap device, run as root: ip tuntap add dev TAP_DEVICE_NAME mode tap user USER group GROUP ip l set dev TAP_DEVICE_NAME up ip l set dev TAP_DEVICE_NAME master virbr0 // or br0 Not a customer bug and it looks like we'll never get around to fixing this (and perhaps it's not even a bug!), as it involves a complicated qemu reproducer. Maybe RHEL8 is better in this regard. So, WONTFIX, I'm afraid. |
Description of problem: asan-instrumented qemu running order of magnitude slower than uninstrumented qemu Version-Release number of selected component (if applicable): libasan-4.8.5-4.el7.x86_64 qemu-kvm-rhev-2.3.0-31.el7_2.1.x86_64 How reproducible: always Steps to Reproduce: 1. rebuild qemu with asan (aka with -fsanitize=address ) 2. run a real VM in qemu instrumented with address sanitizer 3. Actual results: qemu feels even slower than qemu under valgrind/memcheck. Expected results: qemu runs at ~1/2 the usual speed as asan-instrumented programs should Additional info: 1. how to rebuild qemu (rpm): 1. download & install srpm, insert these lines to start of the %build stage: ---- %global optflags %(echo %{optflags} | sed 's/ -g / -ggdb -fno-omit-frame-pointer -fsanitize=address -Wno-error=maybe-uninitialized -Wno-unused-but-set-variable /') %global __global_ldflags %(echo "%{__global_ldflags} -fsanitize=address -lasan") %global __strip %{nil} %global debug_package %{nil} ---- 2. rebuild using rpmbuild -ba ~rpmbuild/SPECS/qemu-kvm.spec. The build will fail at "make check" but usable build will be in BUILDROOT anyway 2. how to run qemu 1. always run qemu within gdb: gdb ~/rpmbuild/.../usr/libexec/qemu-kvm otherwise you'll run into OOMs 2. always use -monitor stdio (or elsewhere) because qemu under gdb requires "c" command to continue booting 3. use virtio-scsi block devices, virtio-blk seems incompatible with asan