Re: [Qemu-devel] Debian 7.8.0 SPARC64 on qemu - anything i can do to speedup the emulation?

[Richard Henderson]

On Aug 22, 2015 9:45 AM, Artyom Tarasenko <address@hidden> wrote:
> For my test case tcg-indirect brings more performance gain than for Dennis: 
>
> git master: 18m31s 
> tcg-indirect: 16m50s 
> #undef  USE_TCG_OPTIMIZATIONS: 14m18s 

Thanks.  That's useful.

>
>
> JIT statistic, before starting the test: 
> (qemu) info jit 
> Translation buffer state: 
> gen code size       31851136/314448896 
> TB count            128224/2457592 
> TB avg target size  18 max=704 bytes 
> TB avg host size    248 bytes (expansion ratio: 13.4) 
> cross page TB count 0 (0%) 
> direct jump count   83840 (65%) (2 jumps=64730 50%) 
>
> Statistics: 
> TB flush count      5 
> TB invalidate count 317160 
> TLB flush count     1180769 
> [TCG profiler not compiled] 
>
> After 
> (qemu) info jit 
> Translation buffer state: 
> gen code size       282903344/314448896 
> TB count            1139744/2457592 
> TB avg target size  17 max=704 bytes 
> TB avg host size    248 bytes (expansion ratio: 14.0) 
> cross page TB count 0 (0%) 
> direct jump count   739828 (64%) (2 jumps=569074 49%) 
>
> Statistics: 
> TB flush count      5 
> TB invalidate count 324362 
> TLB flush count     2050744 
>
> So, TB invalidate count gained only ~ 5000. 
> Yet tcg_optimize is ~7% in the perf top, and tcg_liveness_analysis 
> ~3%. Why do we translate so much? 

I don't know.  It must be something SPARC specific, as I don't see so much for 
alpha.

I'll try to think of good places to collect data.


r~