[SeaBIOS] [Qemu-devel] Hack integrating SeaBios / LinuxBoot option rom with QEMU trace backends
avi at redhat.com
Tue Oct 11 11:08:33 CEST 2011
On 10/10/2011 09:01 PM, Alexander Graf wrote:
> >> For example, one execution of QEMU produced the following log:
> >> $ stap qemu-timing.stp
> >> 0.000 Start
> >> 0.036 Run
> >> 0.038 BIOS post
> >> 0.180 BIOS int 19
> >> 0.181 BIOS boot OS
> >> 0.181 LinuxBoot copy kernel
> >> 1.371 LinuxBoot copy initrd
> > Yeah, there was a thread a bit ago about the performance of the interface to read the kernel/initrd. I think at it was using single byte access instructions and there were patches to use string accessors instead? I can't remember where that threaded ended up.
> IIRC we're already using string accessors, but are still slow. Richard had a nice patch cooked up to basically have the fw_cfg interface be able to DMA its data to the guest. I like the idea. Avi did not.
> And yes, bad -kernel performance does hurt in some workloads. A lot.
The rep/ins implementation is still slow, optimizing it can help.
What does 'perf top' say when running this workload?
error compiling committee.c: too many arguments to function
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