On 07/09/2017 11:29 AM, Emilio G. Cota wrote:
On Sun, Jul 09, 2017 at 11:19:37 -1000, Richard Henderson wrote:
On 07/08/2017 09:50 PM, Emilio G. Cota wrote:
This allows us to generate TCG code in parallel. MTTCG already uses
it, although the next commit pushes down a lock to actually
perform parallel generation.
User-mode is kept out of this: contention due to concurrent translation
is more commonly found in full-system mode.
Um, why do you believe that? Are you suggesting that a multi-threaded
user-only guest is much more likely to share TBs and do much less code
generation total?
Exactly. Also, in user-mode "vCPU threads" (i.e. host threads) come and
go all the time, so this doesn't work well with having a single
code_gen_buffer, which I assumed was non-negotiable.
Ah, yes. For any subdivision N of code_gen_buffer that we choose, at some
point we may have N+1 threads and need to do Something Else.
That's probably something worth commenting somewhere with the "first" #ifndef
CONFIG_USER_ONLY.
r~
