Re: [Qemu-devel] [PATCH v3 35/43] tcg: dynamically allocate optimizer temps

[Emilio G. Cota]

On Wed, Jul 19, 2017 at 21:39:35 -1000, Richard Henderson wrote:
> On 07/19/2017 05:09 PM, Emilio G. Cota wrote:
> >Groundwork for supporting multiple TCG contexts.
> >That is, 2.70% slowdown.
> 
> That's disappointing.  How about using tcg_malloc?
> 
> Maximum allocation is sizeof(tcg_temp_info) * TCG_MAX_TEMPS = 12288, which
> is less than TCG_POOL_CHUNK_SIZE, so we'll retain the allocation in the pool
> across translations.

             exec time (s)  Relative slowdown wrt original (%)
---------------------------------------------------------------
 original     20.213321616                                  0.
 tcg_malloc   20.441130078                           1.1270214
 TCGContext   20.477846517                           1.3086662
 g_malloc     20.780527895                           2.8061013

So will go with tcg_malloc.

BTW, is there any chance that the pool will be initialized before we copy
tcg_init_ctx? That'd mean the main thread has performed translation, which
seems unlikely to me. But should then we bother clearing the TCGProfile
counters after we copy tcg_init_ctx? I don't see how without translation
counters would be !0.

                E.