Re: [RFC PATCH 2/6] accel/tcg: Avoid uncessary call overhead from qemu_plugin_vcpu_mem_cb

[Max Chou]

Hi Richard,

Thank you for the suggestion. I'll do a v2 with this.

Thanks,
Max

On 2024/2/16 4:03 AM, Richard Henderson wrote:
> On 2/15/24 09:28, Max Chou wrote:
> > If there are not any QEMU plugin memory callback functions, checking
> > before calling the qemu_plugin_vcpu_mem_cb function can reduce the
> > function call overhead.
> >
> > Signed-off-by: Max Chou <max.chou@sifive.com>
> > ---
> >   accel/tcg/ldst_common.c.inc | 40 +++++++++++++++++++++++++++----------
> >   1 file changed, 30 insertions(+), 10 deletions(-)
> >
> > diff --git a/accel/tcg/ldst_common.c.inc b/accel/tcg/ldst_common.c.inc
> > index c82048e377e..bf24986c562 100644
> > --- a/accel/tcg/ldst_common.c.inc
> > +++ b/accel/tcg/ldst_common.c.inc
> > @@ -134,7 +134,9 @@ uint8_t cpu_ldb_mmu(CPUArchState *env, abi_ptr 
> > addr, MemOpIdx oi, uintptr_t ra)
> >         tcg_debug_assert((get_memop(oi) & MO_SIZE) == MO_UB);
> >       ret = do_ld1_mmu(env_cpu(env), addr, oi, ra, MMU_DATA_LOAD);
> > -    plugin_load_cb(env, addr, oi);
> > +    if (cpu_plugin_mem_cbs_enabled(env_cpu(env))) {
> > +        plugin_load_cb(env, addr, oi);
> > +    }
> >       return ret;
> >   }
>
> Rather than repeating N times, modify plugin_load_cb and 
> plugin_store_cb just above to avoid the call to 
> cpu_plugin_mem_cbs_enabled().  I expect the compiler is inlining those 
> functions already.
>
>
> r~