Alex Bennée <alex.ben...@linaro.org> writes:
> Shashi Mallela <shashi.mall...@linaro.org> writes: > >> This patchset implements qemu device model for enabling physical >> LPI support and ITS functionality in GIC as per GICv3 specification. >> Both flat table and 2 level tables are implemented.The ITS commands >> for adding/deleting ITS table entries,trigerring LPI interrupts are >> implemented.Translated LPI interrupt ids are processed by redistributor >> to determine priority and set pending state appropriately before >> forwarding the same to cpu interface. >> The ITS feature support has been added to sbsa-ref platform as well as >> virt platform,wherein the emulated functionality co-exists with kvm >> kernel functionality. > > So I'm definitely seeing a slow down in one of my testcases but it > doesn't seem to be HW access related. Via: > <snip> > > So I ran with the hotblocks plugin: > > ./qemu-system-aarch64 -cpu max,pauth-impdef=on -machine > type=virt,virtualization=on,gic-version=3 -display none -serial mon:stdio > -kernel ~/lsrc/linux.git/builds/arm64.initramfs/arch/arm64/boot/Image -append > "console=ttyAMA0" -m 4096 -smp 1 -plugin contrib/plugins/libhotblocks.so -d > plugin -D hotblocks.log > > collected 130606 entries in the hash table > pc, tcount, icount, ecount > 0xffffffc010627fd0, 4, 10, 3998721 - memcpy > 0xffffffc010628288, 2, 6, 3984790 - memset > 0xffffffc01062832c, 3, 4, 1812870 - memset > 0xffffffc0100a8df8, 4, 4, 1743432 - __my_cpu_offset > 0xffffffc01015c394, 2, 4, 1304617 - __my_cpu_offset > 0xffffffc010093348, 3, 3, 1228845 - decay_load > 0xffffffc010093354, 3, 3, 1228447 - decay_load > 0xffffffc01009338c, 3, 2, 1228447 - decay_load > 0xffffffc01009336c, 3, 7, 1180051 - decay_load > 0xffffffc010631300, 3, 4, 1114347 - __radix_tree_lookup > 0xffffffc0106312c8, 3, 12, 1114337 - __radix_tree_lookup > 0xffffffc0106312f8, 3, 2, 1114337 - > 0xffffffc010132aec, 3, 4, 1080983 > 0xffffffc010132afc, 3, 12, 1080983 > 0xffffffc010132b30, 3, 2, 1080983 > 0x000000004084b58c, 1, 1, 1052116 > 0x000000004084b590, 1, 7, 1052116 > 0x000000004084b57c, 1, 4, 1051127 > 0xffffffc01001a118, 2, 6, 1049119 > 0xffffffc01001a944, 2, 2, 1048689 > > So whatever is holding it up is because it's heavily spamming core > functions. Well given I've seen it hit gic_handle_irq > 1000 times already while in the "PCI: CLS 0 bytes, default 64" phase of the kernel boot makes me think the IRQs are just re-asserting themselves and firing continuously. Indeed -d trace:gicv3_redist_set_irq shows a lot of: gicv3_redist_set_irq GICv3 redistributor 0x0 interrupt 26 level changed to 0 gicv3_redist_set_irq GICv3 redistributor 0x0 interrupt 26 level changed to 1 gicv3_redist_set_irq GICv3 redistributor 0x0 interrupt 26 level changed to 0 gicv3_redist_set_irq GICv3 redistributor 0x0 interrupt 26 level changed to 1 gicv3_redist_set_irq GICv3 redistributor 0x0 interrupt 26 level changed to 0 gicv3_redist_set_irq GICv3 redistributor 0x0 interrupt 26 level changed to 1 -- Alex Bennée
