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Diffstat (limited to 'results/classifier/118/performance/2848')
| -rw-r--r-- | results/classifier/118/performance/2848 | 43 |
1 files changed, 0 insertions, 43 deletions
diff --git a/results/classifier/118/performance/2848 b/results/classifier/118/performance/2848 deleted file mode 100644 index c6ff1a455..000000000 --- a/results/classifier/118/performance/2848 +++ /dev/null @@ -1,43 +0,0 @@ -i386: 0.981 -performance: 0.965 -x86: 0.955 -VMM: 0.894 -graphic: 0.758 -device: 0.691 -architecture: 0.665 -semantic: 0.657 -vnc: 0.558 -kernel: 0.484 -socket: 0.461 -ppc: 0.438 -risc-v: 0.330 -virtual: 0.326 -PID: 0.317 -network: 0.305 -boot: 0.303 -mistranslation: 0.286 -arm: 0.255 -KVM: 0.214 -register: 0.177 -TCG: 0.177 -hypervisor: 0.169 -files: 0.168 -permissions: 0.166 -debug: 0.132 -user-level: 0.119 -assembly: 0.093 -peripherals: 0.065 - -i386 max_cpus off by one -Description of problem: -X86 VMs are currently limited to 255 vCPUs (`mc->max_cpus = 255;` in `pc.c`). -The first occurrence i can find of this limit is in d3e9db933f416c9f1c04df4834d36e2315952e42 from 2005 where both `MAX_APICS` and `MAX_CPUS` was set to 255. This is becoming relevant for some people as servers with 256 cores become more available. - -**Can we increase the limit to 256 vCPUs?** -I think so. - -Today, the APIC id limit (see `apic_id_limit` in `x86-common.c`) is based on the CPU id limit. -According to the a comment for `typdef uint32_t apic_id_t;` (see `topology.h`), we can have 256 APICs, but more APICs require x2APIC support. -APIC seems to be no hindrance to increase max_cpus to 256. - -**Can we increase the limit to 512?** Maybe not? We need x2APIC support of which i have no clue. Also there is always a performance risk of exceeding the size at which current data structures work efficiently. |